Watercraft and Snowmobiles
Contents
1. The History of Personal Watercraft The first personal watercraft was designed and patented by a Lake Havasu Arizona resident who sold his idea to the Kawasaki Motor Corporation Kawasaki produced the first personal watercraft the Jet Ski in 1973 This standup model designated the JS400 had a 400 cc twin cylinder engine and quickly became an extremely popular 2 Watercraft and Snowmobiles GASCAP HANDLEBAR GAUGES WINDSCREEN STORAGE HEADLIGHT TAILLIGHT AIR INTAKE Fas d E SHOCK ABSORBER SNOW FLAP FOOT REST PULL STARTER HANDLE FIGURE 1 A Typical Snowmobile Image courtesy of Yamaha Motor Corporation U S A recreational vehicle In 1977 the JS440 was introduced and continued in production until 1992 Currently Kawasaki produces nine different models of watercraft In the mid 1980s Yamaha began producing per sonal watercraft and used a slightly different approach than Kawasaki Instead of the standup models Yamaha designed a sit down model Today the sit down model is the most popular type of personal water craft Figure 2 The personal watercraft industry has seen many different manufactur ers entering the market since the early 1990s with the major players being Kawasaki Polaris Tigershark Arctic Cat Bombardier Sea Doo and Yamaha All of these personal watercraft manufacturers are cur rently building many different types and sizes of machines for recrea tion and high perfo2. e Always route and secure all lines and electrical wires as per the service manual recommendations e Never let oily rags or chemicals sit in the hull for long periods of time e Never drag a personal watercraft across a concrete floor e Beware of corrosion near or around all engine grounds when troubleshooting electrical problems e Always roll the machine on the side indicated by the manufac turer to prevent the possibility of water entering the cylinders from the exhaust system When the hull surface has lost its luster you must clean the surface with water and a neutral detergent After the surface has dried apply rubbing compound and then wax the hull to bring back the original shine and luster If the hull is faded or scratched use number 600 800 wet sandpaper to remove Again finish with rubbing compound and wax Don t use an electric polisher to maintain the finish of a personal watercraft hull Cooling Bilge and Exhaust System Service Cooling and Waterbox System As we mentioned earlier all personal watercraft use a total loss cool ing system The cooling water originates on the high pressure side of the impeller pump The routing of the cooling system starts at the pump outlet goes through a hose to the cylinder and cylinder head and travels from the head through a hose to the exhaust pipe elbow Water from the exhaust pipe elbow flows to the expansion chamber then is sent to the resonator if one is used Fr
3. other as well as with the track Properly aligned skis point straight ahead while misaligned skis point toe in or toe out Toe in skis plow through the snow while toe out skis dart from one side to the other Misaligned skis reduce speed and affect the handling of the snowmobile resulting in a potential hazard Any damaged steer ing components must be repaired immediately Be sure to check the condition of the ski runners for broken welds and dents and ensure that they re fastened securely FIGURE 6 Proper steering alignment requires adjustment of various lock nuts and linkages Image courtesy of Yamaha Motor Corporation U S A SKI ADJUSTER MOUNTING BRACKET FORWARD Brakes As with any vehicle the brakes should be checked periodically You should ensure that the brake pads are in good working condition You should also check the brakes for proper spacing and operation squeeze the lever to determine if the brake pads and spring preload are functioning properly Some models use hydraulic self adjusting brakes inspect these for pad wear Refer to the appropriate service manual for specifications and proper adjustment procedures Clutch Adjustments Proper clutch adjustments are needed to maintain good clutch opera tion and to prolong V belt life When inspecting the clutch system on a snowmobile you need to perform three basic checks clutch offset clutch center to center distance and
4. good you can check for proper track tension To do this you ll need a ruler and a spring gauge Figure 10 As always you should refer to the appropriate service manual for specifications If track tension is incorrect you ll notice a loss in performance that will eventually dam age the track If the track has studs installed compare the stud pattern with that included in the appropriate owner s manual Improper track studding can cause track and chassis damage If the track has been replaced or removed for any reason ensure that it has been installed in the proper direction FIGURE 10 The tech nician is measuring track tension in this illustration image courtesy of Yamaha Motor Corporation U S A SPRING GAUGE After inspecting the track you should now check the condition of the track guide wheels and bearings Ensure proper operation of the track guide clip and inspect wheel and bearing condition The wheels should turn freely without any unusual noise Always replace any damaged wheels or wheel bearings The slide runners better known as Hyfax are long plastic guides attached to the suspension frame to protect it from running against the snowmobile track The Hyfax should be inspected on a regular basis for wear and damage and replaced when necessary Front and Rear Suspension Adjustments Improper suspension adjustment substantially reduces a snowmobile s stability steering and performance Always
5. ll cover each one individually The Snowmobile Engine Snowmobile engines have a two stroke internal combustion design They range in size from a tiny 50 cc single cylinder engine to a huge 1000 cc 150 horsepower four cylinder engine The cooling system 4 Watercraft and Snowmobiles designs found on these recreational vehicles can be air cooled fan cooled forced air or liquid cooled Because there s no transmission attached to snowmobile engines they re quite easy to work on Most snowmobile engines use a reed valve induction system to increase midrange and top end power delivery The engine may use one or more carburetors or none at all fuel injected The most popular type of carburetor found on snowmobiles is the mechanical slide type However you may find some older machines with a fixed venturi carburetor All snowmobiles use a fuel pump either electronic or vacuum to deliver fuel from the fuel tank to the carburetors The Snowmobile Clutch System Virtually every snowmobile uses a variable ratio clutch type transmis sion This type of transmission automatically chooses the correct ratio which allows the machine to quickly move from a standstill to top speed The function of the primary and secondary clutches is similar to the function of the gears in a motorcycle transmission There s an advantage to using clutches instead of gears A transmission that uses gears is at a constant ratio which can t change while
6. attachments are cable actuated An occasional adjustment may be needed The cables don t require external lubrication Watercraft and Snowmobiles FIGURE 19 Directional Nozzle of a Personal Watercraft 33 Directional Nozzle The directional nozzle Figure 19 is also cable actuated in a manner similar to the reverse gate system Again there are times when an adjustment to the cable will be needed but no lubrication of the cable is required Carburetor Adjustments The available adjustments for fixed venturi carburetors are in the low speed and high speed mixture screws Some models also have a midrange adjustment screw These screws are set to the individual manufacturer s specifications which can be found in the appropriate service manual When you make carburetor adjustments on a personal watercraft place the craft in water and adjust the carburetor in the following sequence 1 Set the idle rpm This is achieved with the idle stop screw The idle stop screw adjusts the idle by opening or closing the throttle body butterfly valve The service manual will provide the factory recommended engine rpm but as a rule of thumb this adjustment is around 1500 rpm 2 Set the pop off pressure This requires the use of a small pump in conjunction with an air pressure gauge To test the pop off pres sure a pump hose must be attached to the fuel inlet while the fuel return line on the carburetor is plugged Normally the diap
7. below which is located inside of the pump body housing and draws water into an opening in the hull via a suction and intake casting The water is forced from the pump housing through the outlet nozzle RUBBER o paven DRIVESHAFT HIHHH E ENGINE orvesaer one COUPLER OUTLET NOZZLE FIGURE 12 The basic components of a watercraft power train are shown here Axial Flow Pumps An axial flow pump is designed to operate at a high engine rpm and is used in racing applications where top speed is important An axial flow design actually performs best at a high engine rpm The water in this type of pump is brought in and dispersed straight through the pump housing as shown in Figure 13 Watercraft and Snowmobiles 19 LLLLL LLL LLL IMPELLER 7 IMPELLER gt SHAFT AXIAL FLOW PUMP ae a IMPELLER a IMPELLER MIXED FLOW PUMP FIGURE 13 Axial and Mixed Flow Jet Pumps Courtesy Kawasaki Motor Corp U S A Mixed Flow Pumps The mixed flow pump design performs with high efficiency at low en gine rpm where high thrust is needed for taking off from a stopped position Many experts in the field of personal watercraft consider the mixed flow pump design to be the most efficient On this type of jet pump the water is directed outward of the pump housing and then back to the center as Figure 13 illustrates Watercraft Impellers The impeller on a personal watercraft dif
8. clutch alignment Clutch offset The primary and secondary clutches must have a specific amount of offset Figure 7 Offset is required because the fixed sheave on the primary clutch is on the opposite side of the fixed sheave on the secondary clutch Providing the correct amount of offset will keep the belt pressure against the fixed sheaves as the sliding sheaves change position An excess amount of offset can result in uneven wear of the V belt Watercraft and Snowmobiles 11 FIGURE 7 The tech nician is measuring clutch offset in this illustration image courtesy of Yamaha Motor Corporation U S A Clutch center to center distance Clutch center to center distance is the measurement between the center of the primary clutch and the center of the secondary clutch Figure 8 Engine torque can cause the center to center distance to shorten as the primary clutch is pulled to wards the secondary clutch which will hinder clutch performance Some performance models use an engine break which is a piece of metal that prevents the engine from moving under excessive torque FIGURE 8 The tech nician is measuring clutch center to center distance in this illustration Image courtesy of Yamaha Motor Corporation U S A Clutch alignment Clutch alignment is the adjustment made to bring both clutches in line Proper alignment is achieved by moving the en gine on its mounts so the engine s crankshaft is in a parallel l
9. many cases if a gear ratio change is desired both the sprockets and the chain must be replaced The Snowmobile Track The track on a snowmobile is made of a rubber and fiber compound similar to the materials found in a V belt Some tracks have metal rods that are used to help make the track more durable These tracks are extremely durable and long lasting as long as they re properly maintained Watercraft and Snowmobiles Road Test 1 At the end of each section of Watercraft and Snowmobiles you ll be asked to check your understanding of what you ve just read by completing a Road Test Writing the answers to these questions will help you review what you ve learned so far Please complete Road Test 1 now 1 The jackshaft connects the to the 2 The primary and secondary clutches are attached by a 3 What is used to lubricate the chain and sprocket in a snowmobile gear case 4 The secondary clutch is mounted on the 5 Cooling systems used on snowmobiles can be i or cooled systems 6 True or False Some snowmobiles use the fixed venturi type of carburetor 7 The primary clutch used on a snowmobile mounts on the True or False When a snowmobile begins moving the primary clutch is moving much slower than the secondary clutch Check your answers with those on page 43 SNOWMOBILE MAINTENANCE This section of your study unit focuses on snowmobile maintenance We ll begin with running checks wahich are performed
10. nance chart located in the general information or maintenance section of the service manual Periodic maintenance is generally broken down into the following hours 10 25 50 and 100 hours We ve provided a typical personal watercraft maintenance table for you to see Remember this is an example chart Some watercraft require initial maintenance checks to ensure proper functioning Note There are items that require the attention of the operator and others that need the attention of a technician Watercraft and Snowmobiles 29 EXAMPLE PERIODIC MAINTENANCE CHART Description 10 25 50 100 Performed Hrs Hrs Hrs Hrs by Lubrication corrosion protection Operator Ignition timing Technician Spark plug replacement z Technician Throttle choke cable inspection lubrication i Operator Flame arrester inspection Technician Carburetor adjustments Technician Oil injection pump adjustment Technician Fuel filter inspection s Technician Fuel filter replacement Technician Fuel tank straps Operator Oil tank straps 7 Operator Engine head bolt torque Technician Steering system Technician Reverse system inspection K Technician Trim system inspection Technician Fastener tightening flame arrester carburetor s engine jj Technician mounts exhaust system etc Muffler battery and reservoir fasteners i Oper
11. p VVN transmission drive V belt Hypoid gear lubricant jackshaft air fan or liquid True engine False False plow through the snow dart from one side to the other Premature belt wear The clutch alignment Remove the V belt and rock the secondary clutch back and forth Main seal or gasket Ruler and spring gauge Alcohol 10 Engine fogging 2 10 DO SS ee IS True axial flow mixed flow Mixed flow Axial flow fixed venturi Impellers push water while propellers pull water Through the use of a check valve metacenter waterbox True To remove water from the engine compartment Boiling water on the blade surface caused by low pressure False By flooding the carburetor and preventing the spark one tablespoon trickle charger False 13 15 Examination ONLINE EXAMINATION For the online exam you must use this EXAMINATION NUMBER 03302100 When you re confident that you ve mastered the material in your studies you can complete your examination online Follow these instructions 1 Write down the eight digit examination number shown in the box above 2 Click the Back button on your browser 3 Click the Take an Exam button near the top of the screen 4 Type in the eight digit examination number
12. seals When replacing the bearings on this design loosely mount the housing bolts install the engine and torque the housing mounting bolts to the manufacturer s specifications Some drive system bearing housings have a non self centering bearing design This design has two bearings that require shimming to correct any excessive shaft end play To center the housing and driveshaft remove the old silicone and shim between the housing flange and hull bulkhead until the shaft is within the manufacturer s specifications on the top and sides then seal the housing to the hull Note Some models incorporate an access panel to inspect the drive line housing Pump Assembly The jet pump impeller case has guide vanes that straighten out the water which prevents the hull from torquing to one side during ac celeration Most impellers employ three to five blades The nozzle ac celerates water and increases thrust while the steering nozzle is used for directional control As you know there are two types of jet pumps used on personal water craft an axial flow and a mixed flow The axial flow design has water flow through the impeller that s parallel to the axis of the impeller The impeller has a wing shaped impeller blade that lifts the water This system uses a non shim impeller If there s excessive tip clearance the component will need replacement The mixed flow design allows 32 Watercraft and Snowmobiles water to flow th
13. the diaphragm mechanism precisely regulates the amount of fuel in the fuel chamber As we mentioned earlier the regulator portion of this type of carbure tor primarily affects engine operation at throttle openings of or less in response to the engines high manifold pressure The regulator is an adjustable component and can be tuned to most engine configura tions The term most commonly used for this adjustment is pop off pressure Pop off is a relative term that refers to the pressurization of the needle valve via compressed air through the fuel inlet and noting the pressure necessary to open the needle valve or pop it off its seat The higher the pressure that s required the higher the pop off pressure The Mikuni Super BN performs like a conventional carburetor as the throttle is opened through and past throttle This is achieved through replaceable jets and adjustment screws that make changes in fuel cali bration As the throttle plate is turned beyond opening the engine replaces manifold pressure with air velocity Manifold pressure is the pressure difference generated by the engine against a closed or nearly closed throttle plate As the throttle is opened the carburetor is no longer controlled by the regulator portion and responds as a normal carburetor does The air velocity is drastically increased as the engine revs creating the venturi effect or low pressure within the carbure tor venturi As we know from past stu
14. this procedure Tilt the watercraft onto the manufacturer s designated side when emptying the engine compartment Once this procedure is completed reconnect and tighten the bilge hose clamps Step Four Checking the Fuel System Remove the fuel tank and drain any fuel into an appropriate container Sand and water may have entered the fuel tank during the season so it must be thoroughly cleaned using a high flashpoint solvent Some models have sediment bowls and fuel filters installed on or near the fuel tank these must be drained and cleaned or replaced Be sure to properly install all O rings to prevent any air from entering the sys tem Remember the fuel system must be airtight to operate properly If there are leaks in the fuel system the fuel pump will suck air into the system which can cause engine failure After the fuel has been drained start the engine and run it for about 15 seconds and shut it off Repeat this start and stop procedure until all of the excess fuel has been used and the engine will no longer run Once the fuel has been removed from the lines and burned in the engine remove the flame arrester and clean it with soap and water Spray some multipurpose lubricant into the mouth of the carburetor bore and reinstall the flame arrester Step Five Lubricating the Internal Engine To lubricate the cylinder walls remove the spark plugs and pour about one tablespoon of motor oil into each spark plug hole Figure 20 Pus
15. LVE MAIN JET THROTTLE PLATE FULLY OPEN FIGURE 15 A cross section of a fixed venturi carburetor with the throttle plate 34 open and wide open is shown here At the 3 open stage the main jet begins feeding the carburetor and the increased velocity draws the fuel into the inner venturi At the fully open stage all fuel feeding ports are exposed and the maximum amount of fuel is entering the engine Watercraft and Snowmobiles Fuel Pressure Regulation One drawback of the fixed venturi carburetor is that it s sealed and can t vent the fuel chamber to the atmosphere If a fixed venturi car buretor attempted to vent its fuel the fuel would leak into the hull and create a serious safety hazard The Mikuni Super BN fuel chamber is controlled by the regulator dia phragm Fuel is on one side of the carburetor and atmospheric pressure is on the other Fuel in the chamber is drawn in by the pressure differ ence created by the engine The diaphragm moves in response to the reduction of fuel as well as the effect of the atmospheric pressure that s pushing against it The diaphragm and the needle valve arm allow fresh fuel to enter the fuel chamber Fuel enters the chamber under pressure from the fuel pump with enough force to push the diaphragm back even with resistance from the atmospheric pressure When the fuel chamber is once again filled the diaphragm relieves the pressure on the arm and the needle valve closes This is how
16. O ATMOSPHERE ARM DIAPHRAGM JET THROTTLE PLATE 1 4 OPEN VALVE FUEL RETURN LINE INNER VENTURI HIGH SPEED ADJUSTER CLOSED HIGH SPEED MAIN JET FIGURE 14 A cross section of a fixed venturi carburetor at idle and with the throttle plate 4 open is shown here At the open stage the bypass ports become exposed and additional fuel is allowed to enter the engine 24 Watercraft and Snowmobiles CHECK VALVES INLET PULSE LINE JCA FUEL PUMP FILTER FUEL RESTRICTOR ma DIAPHRAGM pees A FUEL FUEL INLET LINE pzz 77 RETURN LINE Y THROTTLE PLATE V o 1E INNER Y oe Se T VENTURI BYPASS PORTS i LOW SPEED OUTLET LOW SPEED aE D e yee A A ADJUSTER 3 T CLOSED ASSEMBLY ly T me e AN BA az SZ Vivian TR SSN l FUEL VENT REGULATOR LOW SPEED ANTI SIPHON HIGH SPEED CHAMBER TO ATMOSPHERE ARM DIAPHRAGM JET VALVE MAIN JET THROTTLE PLATE 3 4 OPEN CHECK VALVES INLET PULSE LINE ERR FUEL PUMP FILTER FUEL RESTRICTOR DIAPHRAGM e FUEL FUEL INLET LINE GZ 7 RETURN LINE Z Wy Y Ate s a THROTTLE PLATE ISS SQ af mm VENTU 5 e A A SW SS VENTURI BYPASS PORTS k 47 LOW SPEED OUTLET ADJUSTER f E HIGH SPEED NEEDLE ae in j ADJUSTER Ex i WN CLOSED ASSEMBLY yy es i f mig RS ae Yi ARM SPRING a aun NNT TEN SSS SSS l FUEL VENT REGULATOR LOW SPEED ANTI SIPHON HIGH SPEED CHAMBER TO ATMOSPHERE ARM DIAPHRAGM JET VA
17. Study Unit Watercraft and Snowmobiles By Ed Abdo About the Author Edward Abdo has been actively involved in the motorcycle and ATV industry for more than 25 years He received factory training from Honda Kawasaki Suzuki and Yamaha training schools He has worked as a motorcycle technician service manager and Service Parts department director After being a chief instructor for several years Ed is now the Curriculum Development Manager for the Motorcycle Mechanics Institute in Phoenix Arizona He is also a contract instructor and administrator for American Honda s Motorcycle Service Education Department Preview Throughout this program you ve had the opportunity to learn about the exciting field of motorcycle and ATV repair This study unit will help you to understand the basic design features of the typical snowmobile and personal watercraft A brief history of each type of machine and some basic maintenance guidelines are provided Keep in mind while you read through this study unit that we re covering only the basics of these machines A complete program could be designed for each machine but we ll provide the basic information you ll need to understand how these machines function When you complete this study unit you ll be able to e Understand the theory of operation for snowmobiles and personal watercraft e Identify the different types of engines e Understand propulsion drive system operation e Understand b
18. asic maintenance e Properly prepare snowmobiles and personal watercraft for long term storage INTRODUCTION 9 gg 5st a SL Fle HG A ee R EG 1 The History of Snowmobiles The History of Personal Watercraft SNOWMOBILE THEORY OF OPERATION 2 3 The Snowmobile Engine The Snowmobile Clutch System The Snowmobile Chain Gear Case The Snowmobile Track SNOWMOBILE MAINTENANCE 0 2 26 8 Running Checks Non Running Checks Snowmobile Storage PERSONAL WATERCRAFT THEORY OF OPERATION 17 Personal Watercraft Power Train Steering Cooling and Bilge Systems Watercraft Fuel Systems Electrical Circuits Hull Configurations and Components PERSONAL WATERCRAFT MAINTENANCE 28 Hull Finish Care Cooling Bilge and Exhaust System Service Personal Watercraft Driveshafts Fuel Pumps Rev Limiter Engine Overheating Limiter Troubleshooting Symptoms Personal Watercraft Storage ROAD JES SNSWERS 54 oe eee tee eee ee eee 43 Ex RAIN AION Srey ees Sek Se ee Se ea eS 45 Watercraft and Snowmobiles INTRODUCTION Many motorcyclists also own ATVs snowmobiles and personal water craft Because motorcycling is a seasonal sport in most parts of the country dealerships must offer other equipment to customers Many motorcycle and ATV dealerships sell snowmobiles and personal water craft to keep their customers coming into the dealership on a year round basis It isn t unusual t
19. ator Fuel lines check valve and fuel system pressure test Technician Fuel vent line pressure relief valve inspection Technician Inspect clean engine drain tube Technician Bilge system water tank trap drains inspection Operator Battery condition Technician Electrical connections Technician Impeller shaft reservoir oil level condition i Technician Impeller condition and clearance 7 Technician Driveshaft condition Technician PTO flywheel lubrication i Operator Water intake grate condition 7 Operator Hull condition Operator Cooling system flushing daily if used in salt water Operator Before you perform any maintenance on a personal watercraft there are certain operational precautions that you must follow e Never operate a personal watercraft without cooling water for more than 15 seconds e Always check for sand in the cooling system and exhaust mani fold Sand in the cooling system will cause overheating and is a good sign that the craft has been beached or run in water that was less than two feet deep e When removing the battery always disconnect the negative battery ground first 30 Hull Finish Care Watercraft and Snowmobiles e Never reuse a gasket or an O ring e Never reuse retaining rings after you ve removed them e Always use the manufacturer s recommended and approved chemicals otherwise you may cause hull or paint damage e Never overload the tow rope holes in the hull
20. ble clutch transmission achieves engagement speed Figure 4 6 Watercraft and Snowmobiles SLIDING SHEAVE FIXED PRIMARY SHEAVE CLUTCH WEIGHT SPRING SECONDARY ae CLUTCH ENGAGED ENGAGED ENGAGED 3 5 1 RATIO 2 1 RATIO 1 1 RATIO CLUTCH ASSEMBLY FIGURE 4 This illustration shows the change in the primary and secondary clutches from idle to a 1 1 ratio Image courtesy of Yamaha Motor Corporation U S A The Secondary Clutch The secondary clutch is designed to sense the load requirements of the track and reacts by shifting to a ratio that allows the engine to op erate within its power band At first the secondary clutch is turning much more slowly than the primary clutch Because the secondary clutch drives the track the track will also go faster in relation to the speed of the engine The secondary clutch uses a torque spring and sensing ramps Figure 5 to maintain the proper V belt pressure and to maintain the proper clutch ratio The secondary spring forces the secondary sheaves closed making the V belt ride on the outer circumference of the sheaves As the primary clutch shifts to a higher ratio the belt rides to the outer perimeter of the primary sheaves As this occurs the belt pressure tries to pull the V belt down between the secondary sheaves causing a higher ratio The spring and cam are designed to prevent the sheaves from being forced apart by the belt pressure until it s enough to over
21. come the predetermined spring pressure thus allowing maximum use of the primary gear Watercraft and Snowmobiles FIGURE 5 Secondary clutch springs and ramps react to the torque on the clutch As the springs and ramps SECONDARY SHEAVES move the clutch opens TORQUE and allows the belt to SENSING RAMPS slide down toward the center portion of the SECONDARY clutch image courtesy of Yamaha Motor Corporation U S A The secondary spring prevents the V belt from being pulled between the sheaves by forcing the clutch sheaves closed This spring is pre loaded with both an axial and a torsional pressure via the cam or spring seat Most of the force against the sheaves is in the form of torque rather than pressure As belt pressure pulls the belt between the sheaves the cam twists on its ramps and applies a predetermined amount of pressure on the V belt at all times The Snowmobile Chain Gear Case The snowmobile chain case houses both the drive sprocket and driven sprocket as well as the primary chain and a chain tensioner arrange ment These components are lubricated by a hypoid gear lubricant similar to that used in the final drive gear case on a shaft driven motor cycle The drive sprocket is attached to the jackshaft of the machine while the driven sprocket attaches to the drive shaft which drives the track The gear ratio between the jackshaft and the drive shaft can be changed for different snowmobile uses In
22. consider the conditions in which the snowmobile is used and adjust the suspension accordingly Adjust the snowmobile s suspension Figure 11 to the softest possible setting without causing the snowmobile to bottom out A setting that s too hard is uncomfortable and provides poor handling A setting that s too soft provides poor handling causes speed loss and causes damage over rough terrain For general use comfort is a primary concern and for performance handling is the objective A compromise between these two must be made depending upon the kind of riding and terrain Watercraft and Snowmobiles 15 FRONT STOPPER BAND REAR STOPPER BAND FIGURE 11 Tightening or loosening the bolts on the rear suspension of a snowmobile will increase or decrease the suspension s spring tension Image courtesy of Yamaha Motor Corporation U S A You should always test ride a snowmobile after you ve serviced it Pay close attention to clutch engagement rpm and shift rpm Check for vibration and the overall feel of the snowmobile Before delivering any machine to the customer you should always clean and polish it Ensure that all fingerprints and grime have been removed A good rule of thumb is to deliver a machine cleaner than you received it A technician who is recognized for delivering quality back to his or her customer will hold a definite advantage in the marketplace Final Checks Ensure all nuts and bolts ar
23. d be turned on its side to view the drive sprockets Track Tension And Alignment Traction is a major player in the performance of a snowmobile An improperly adjusted or misaligned track will cause problems with performance and increase the chances of premature component wear Inspect the tension alignment and general condition of the track To check the track tension and alignment raise the rear of the snowmo bile and support it on jackstands Start the engine and spin the track for a few seconds then turn the engine off and check the track align ment by confirming the alignment of the slide runner All distances should be equal as shown in Figure 9 NO GOOD GOOD NO GOOD SLIDE RUNNER TRACK SLIDE RUNNER TRACK SLIDE RUNNER TRACK Ne g FORWARD FORWARD n K R GAP BETWEEN SLIDE RUNNER GAP BETWEEN SLIDE RUNNER AND EDGE OF TRACK WINDOW AND EDGE OF TRACK WINDOW WHEN SHIFTED TO RIGHT WHEN SHIFTED TO LEFT TIGHTEN THE RIGHT TRACK TIGHTEN THE LEFT TRACK ADJUSTING NUT AND LOOSEN ADJUSTING NUT AND LOOSEN THE LEFT TRACK ADJUSTING NUT THE RIGHT TRACK ADJUSTING NUT FIGURE 9 The center illustration demonstrates proper track alignment image courtesy of Yamaha Motor Corporation U S A 14 Watercraft and Snowmobiles When checking track and slide runner alignment and condition remem ber to check the condition and alignment of the guide wheels at the front of the track Once you ve determined that the track alignment is
24. dy units fuel flow through the carburetor is caused by the differences in pressure between higher atmospheric pressure on the diaphragm and lower pressure within the carburetor venturi The air velocity creates such a strong pressure difference the pop off pressure has virtually no effect on calibration past throttle Accurately tuning a fixed venturi carburetor requires understanding all of its functions and following a few basic rules 26 Watercraft and Snowmobiles Note The carburetor will work only as well as your engine does This means that the performance of a carburetor won t make up for a weak or worn out engine Electrical Circuits The ignition systems found on personal watercraft are either AC or DC CDI systems that require no maintenance The charging systems found on personal watercraft are permanent magnet types and can be half wave full wave or three phase systems The basic function of the charging system is to keep the battery in a fully charged state The electric starter motor is the primary electrical component that drains power from the battery Most personal watercraft use AC lighting systems that are similar in design to those we ve discussed in previ ous study units Hull Configurations and Components Personal watercraft hulls are constructed according to various designs Figure 16 Some of the more common ones include e A V bottom with strakes which provides a soft ride at high speeds e A V bottom w
25. e of adjusting the carburetor is that the circuits tend to overlap one another and contribute to the total fuel delivery to the carburetor For example changing the low speed jet will have an effect on the fuel delivery at full throttle The fuel pumps used on personal watercraft are either internally or externally mounted units that are operated by crankcase pressure Other than checking the lines for cracking there s no maintenance required for these components The only maintenance that s required is inspecting the fuel lines for damage Fuel Lines The fuel petcock supplies fuel to the fuel filter and then to the carbure tor through fuel lines On twin carburetor models the return line from the main carburetor feeds the second carburetor The return line from the second carburetor returns to the fuel tank On triple carburetor models the return lines from the first and third carburetors feed the second carburetor The return line from the second carburetor returns to the fuel tank The vent line from the fuel tank has a one way check valve that can easily be checked via a pressure pump The appropriate service manual will give you the proper specifications to test this valve Watercraft and Snowmobiles Rev Limiter 35 Fuel Filters Fuel filters will allow water to pass through them and should be cleaned and inspected as part of any routine service In order to pre vent any air or water leaks ensure that all O rings and seal
26. e secure and all lock tabs and coffer pins are in place If you removed a lock tab or coffer pin during servicing be sure that you installed a new one Snowmobile Storage There are five basic steps you should follow to properly prepare a snowmobile for storage Performing these steps will prolong the life of a snowmobile and prevent heavy repair Cleaning Remove all dirt grease mud and grime that the machine has collected internally and externally Clean the snowmobile with a quality degreaser and soap and water When you ve finished clean ing ensure everything is thoroughly rinsed Lubricate the chassis In order to fight corrosion lubricate all of the external moving parts of the machine with a high quality general purpose lubricant Ensure lubrication of the suspension linkages and all pivot points on the snowmobile 16 Watercraft and Snowmobiles Fuel conditioning As with storing a motorcycle in the off season storing a snowmobile during the summer months requires that you properly prepare the fuel The reason for this is that alcohol which is found in many fuels can carry moisture into the engine Moisture corrodes internal engine parts The alcohol in the fuel also reduces the protection that s provided by rust inhibitors added to most oils Thus proper storage techniques are essential to prevent damage to the internal components of a snowmobile engine In the summer many snowmobile owners will start the engine
27. e valve com prise the regulator portion of a Mikuni Super BN carburetor Actually the Mikuni Super BN is part carburetor and part fuel regulator The fuel regulator controls the flow of fuel at low speeds idle to throttle and the carburetor portion controls the flow of fuel at higher speeds from throttle to full throttle When the engine is idling fuel is forced through the low speed jet to the low speed outlet In order for the machine to idle fuel must flow through the bypass ports and the low speed adjuster The low speed adjuster is responsible for the fuel flow when the machine is idling A properly tuned machine idles smoothly and has a quick initial throttle response Watercraft and Snowmobiles As the throttle valve opens low speed bypass ports are increasingly exposed to the flow of incoming air Figure 14 As covered in a previ ous study unit their function is to help the carburetor transition from low speed to high speed operation They prevent the engine from bogging down and hesitating The size of the low speed jet affects the flow of fuel through the bypass ports for low speed operation Also low speed performance is affected by the regulator portion of this type of carburetor The regulator portion can be tuned to suit the con ditions of the watercraft As the carburetor transitions to its high speed fuel circuit at about 4 throttle fuel is drawn through the anti siphon valve and then through the high speed
28. fers from a propeller on a boat in that propellers pull water and impellers push water The impeller provides thrust by using a combination of water flow and water pres sure in a precision closed area The blades of an impeller overlap thereby trapping water and forcing it through the impeller and finally into the duct and nozzle Nozzle The nozzle on a watercraft is comprised of two separate pieces A piv oting piece is needed for steering the craft and a tapered portion is part of the jet pump housing 20 Steering Watercraft and Snowmobiles Forward Neutral and Reverse Many personal watercraft have a gate activated by a cable that controls the flow of water A fully open gate allows the water to flow through the nozzle and moves the watercraft in a forward motion A partially closed gate allows some of the water flowing from the pump to flow outward through the nozzle while the rest of the water is deflected downward and forward This creates a neutral position because the water is being equally dispersed in both forward and aft directions A fully closed gate completely deflects the water in a down ward and forward motion allowing the watercraft to move in reverse Steering a personal watercraft is accomplished through motorcycle type handlebars The handlebars are attached to a cable which turns the nozzle at the pump housing Cooling and Bilge Systems Most jet pumps have two hoses attached to the housing One
29. for any damage and grease the cable ball joints Lubricate the pivot points on the steering nozzle Figure 22 Wash the watercraft using a mild soap and dry it thoroughly Drain the engine compartment after you wash the craft and apply a high quality grade wax to the fiberglass Spray all exposed metal parts with a high quality multipurpose lubricant Install the engine cover on the hull but be sure to allow for ventila tion Finally cover the craft and store it in a clean dry environment Watercraft and Snowmobiles 41 FIGURE 21 When removing the battery from the watercraft always remove the ground cable first to prevent sparks FIGURE 22 The technician in this photo is lubricating the pivot points of a nozzle Step Eight Preparing the Watercraft for Use If the watercraft was properly prepared for storage it should be in good condition when it s time to ride again No matter how well a watercraft has been prepared for storage the cold winter months can still take their toll Inspect the watercraft hoses and connections for weathering or cracking Be sure to check all cable operated components verifying that condensation didn t harm them while the watercraft was in stor age Before installing the battery ensure that it s fully charged After mounting the battery coat all cables and terminals with grease to pre vent corrosion Fill the fuel tank top off the oil tank when applicable and start the engine Let
30. ge courtesy of Yamaha Motor Corporation U S A PRIMARY CLUTCH SECONDARY CLUTCH The Primary Clutch The primary clutch mounts on the end of the crankshaft and has two purposes e To determine engagement speed e To maintain engine speed at a constant rpm with the power band When idling before engagement speed the sliding sheave is held away from the fixed sheave by a spring Before engagement speed the primary clutch sheaves are so far apart the V belt doesn t make enough contact to move Therefore the V belt isn t engaged because it s more narrow than the space between the sheaves as shown in Figure 4 As engine rpm increases centrifugal force begins to make the weights in the clutch move outward The force of the weights is enough to push the sliding sheave against the primary spring The spring has a specific preload that prevents the sliding sheave from moving until the centrifugal force becomes great enough to overcome the predeter mined primary spring pressure Figure 4 When the sliding sheave moves close enough to the fixed sheave which is located on the crankshaft the gap between the sheaves becomes narrow enough to engage the V belt This allows the sheaves to exert more pressure against the outside of the V belt The friction created at the V belt and sheaves becomes great enough to turn the secondary clutch Power is then transferred from the V belt to the secondary clutch At this time the varia
31. h the starter button to turn the engine over to thoroughly lubri cate the cylinder walls Remember to leave the spark plugs out of the cylinder heads but be sure they re grounded properly against the cylinder head or exhaust manifold to prevent ignition damage After you ve lubricated the engine cylinder walls reinstall the spark plugs and have a new set handy for the next season Chances are the current spark plugs won t start the craft when it comes out of storage due to the added oil in the cylinder 40 Watercraft and Snowmobiles FIGURE 20 Pouring oil in the cylinders will prevent corrosion of internal components Note that the spark plugs are grounded to the cylinder heads preventing any ignition problems Step Six Preparing the Battery Remove the battery from the watercraft by disconnecting the negative cable first Figure 21 and then the positive cable Clean the outside of the battery with a solution of baking soda and water to neutralize any acid on the outside of the battery and then rinse it with water Check the water level and fill the battery with distilled water as needed Charge the battery with a trickle charger once a month while it s out of the watercraft and grease the terminals to prevent corrosion buildup Step Seven Preparing the Cables and Cleaning Lubricate the throttle and choke cables with a pressure cable lubricator and apply grease to the cable ends Check the steering cables
32. hich causes the fuel to flow from the fuel tank to the car buretor system Carburetors As mentioned earlier carburetors used on personal watercraft are fixed venturi designs Although the fixed venturi carburetor has a simple design the operation is precise As the name suggests the carburetor is fixed and doesn t have a slide for changing the size of the venturi A throttle plate controls the amount of air entering the engine intake tract When the rider opens the throttle control for an increase in speed the throttle valve opens between the carburetor and the engine intake tract allowing more air and fuel to enter the engine combustion chamber The most popular fixed venturi carburetor found on personal watercraft is the Mikuni Super BN carburetor Through the cutaway illustration in Figure 14 we can learn how this type of carburetor functions under various conditions The fuel pump diaphragm draws fuel via the fuel inlet line through a check valve The diaphragm then forces the fuel through another check valve and filter Any excess fuel is diverted back to the fuel tank via the fuel re turn line Also a fuel restrictor is used to regulate fuel pressure for the fuel pump The fuel that passes through the fuel filter goes straight to the needle valve assembly and then into the fuel chamber area The regulator diaphragm arm spring arm and vent control the flow of fuel into the fuel chamber These components along with the needl
33. hragm and its cover are removed during this test Ensure that the needle valve is wet at all times and pressurize the carburetor with the pump until the needle valve pops off Then check to see at what pressure the valve closes and reseals Test this at least three times 34 Fuel Pumps Watercraft and Snowmobiles to ensure consistent readings Refer to individual manuals for specifications 3 Set the low speed adjuster screw This screw should be set to maintain the idle speed and to keep the engine running smoothly at low engine rpm As the idle speed is adjusted the low speed mixture screw is also affected Turning the screw in a clockwise direction causes the mixture to become more lean because it closes off the fuel from the carburetor Turning the screw in a counterclockwise direction causes the mixture to become richer 4 Set the midrange adjuster screw if applicable Some personal watercraft have a midrange adjuster screw that s adjusted in the same manner as the low speed screw This screw should be set to throttle 5 Set the high speed adjuster screw This screw should be set for full throttle operation The high speed adjuster screw is used in conjunction with the main jet Rotating the screw clockwise causes the mixture to become lean Rotating the screw counterclockwise causes the mixture to become richer 6 Return the engine to idle and recheck the rpm after making all adjustments The reason for this sequenc
34. id cooled snowmobiles be sure to check the coolant level and fill as required To ensure that the coolant is at the proper level perform this procedure several times while the engine is running and hot As with motorcycles always use a 50 50 mixture of ethylene glycol and distilled water Prior to cleaning coolant systems refer to the service manual or any technical bulletins regarding coolant level and bleeding On units that have bleed screws at the rear of the system raise the back of the snowmobile to trap air at the bleed points Remember air is bled from the highest part of the cooling system Note You should also check the headlight and taillight for proper operation and check the headlight aim Non Running Checks Snowmobile Steering Alignment Each time the snowmobile is serviced check and adjust the steering and ski alignment Proper alignment is the most important item for proper snowmobile handling steering Adjusting this area of the snowmobile involves verifying the proper operating condition of the front suspension handlebar skis and ski runner Note that some snowmobile models use conventional oil dampened shocks in addi tion to springs these items must be checked for wear A proper steering alignment Figure 6 ensures that the handlebar is straight when the skis are straight This adjustment is performed in conjunction with the ski alignment Skis should be parallel with each 10 Watercraft and Snowmobiles
35. ine with the jackshaft Proper alignment ensures that the V belt runs in a straight line If the crankshaft and jackshaft are incorrectly aligned the V belt will have a tendency to be pulled to one side This will cre ate uneven side pressure and will prematurely wear out the V belt as well as allow incorrect clutch shifting and clutch wear There are two types of misalignment the crankshaft and jackshaft may not be par allel or the shafts may not be on the same plane When you look down on the engine and jackshaft the shafts should be parallel with each other Also while you look at the crankshaft and jackshaft ends both shafts should be on the same level plane Incorrect alignment occurs if the engine is mounted higher on one side If this condition occurs you ll need to shim the engine to correct it Watercraft and Snowmobiles Clutch alignment should be done during general maintenance This procedure must also be performed any time the engine is moved or removed from the chassis Clutch alignment is measured with a special alignment tool available from snowmobile manufacturers To meas ure the clutch offset place the clutch alignment tool behind the clutch sheaves from the secondary sheave to the primary sheave Hold the tool flat against both edges of the secondary sheave at the tip and check for any gap between the tool and the primary sheave If there s more than the specified amount of clearance an adjustment will be necessa
36. it run for 15 second intervals and be sure to 10 Watercraft and Snowmobiles let the engine cool off between starts After starting the machine a few times replace the spark plugs Don t install new spark plugs before starting the engine this will prevent fouling a new set of spark plugs from the oil installed in the cylinders Finally clean and buff out the wax on the personal watercraft Road Test 4 Another name for the main muffler on a personal watercraft is the True or False All personal watercraft carburetors use a low speed adjustment screw What is the bilge system on a personal watercraft used for What causes cavitation in the drive system on a personal watercraft True or False All personal watercraft carburetors have a midrange adjustment screw What are the two ways that personal watercraft manufacturers limit the rpms rev limiters on watercraft In order to lubricate the cylinder walls on a personal watercraft when preparing it for storage you should pour about of motor oil into each spark plug hole A should be used to charge a battery once a month while it s in storage True or False Engine hoods should be modified to personalize watercraft The charging voltage for a correctly functioning personal watercraft charging system will show a voltage of to VDC at approximately throttle Check your answers with those on page 43 Road Test Answers o oO FF U N e N o N oa
37. ith strakes and pad which is the same as the V bottom with strakes except it has an additional pad to increase the top speed of the craft e A tri cathedral hull with pad is similar in design to a V bottom with a pad Hull outsides are added primarily in the forward section of the hull This design is more stable at high speeds but provides for a rough ride in choppy water conditions FIGURE 16 Personal watercraft hulls come in different designs and configurations Watercraft and Snowmobiles FIGURE 17 A basic sit down type personal watercraft hull with no other components is shown here Hull units consist of two pieces that are glued together and purchased as a single unit Figure 17 Engine hoods cover the engine compart ment and act as a ventilation system As a result engine hoods should never be modified Sit down models may use the upper hull or even a portion of the seat for engine compartment ventilation Hulls on personal watercraft are considered to be self righting Three factors affect self righting ability e Buoyancy which is formed by the upper half of the craft han dlebar engine hood side rails This is the displaced center of buoyancy e The center of gravity CG which on a personal watercraft is low because of the engine and drive line being placed in the lower half of the watercraft e The metacenter which is a point at the intersection of a vertical line drawn through the center of g
38. lling When working on multicylinder engines with individual carburetors it s necessary to repeat the pro cedure in each of the individual cylinders Waxing In order to prevent body corrosion wax all of the painted surfaces with a high quality wax This will keep the machine looking like new Watercraft and Snowmobiles 17 10 Road Test 2 True or False On a liquid cooled snowmobile the coolant mixture should have more antifreeze ethylene glycol in it than a liquid cooled motorcycle because of the cold temperatures that it s operated in A snowmobile with excessive toe in will tend to A snowmobile with excessive toe out will tend to On a snowmobile what can result from excessive clutch offset If a customer s snowmobile has a clutch related problem that requires troubleshooting what s the first thing to check Describe an easy way to check the chain tension in a chain case on a snowmobile If the chain case oil level is low where will the problem most likely be located What two tools are required to properly check snowmobile track tension What substance is used to raise the octane level in gasoline and also causes a storage problem on a snowmobile Most manufacturers will recommend spraying a type of oil into the engine through the carburetor to protect the internal engine components from moisture during extended periods of storage What is this procedure known as Check y
39. m the damage that results from an engine that s revved past the manufacturer s engine redline There are two basic ways to limit engine rpms 1 Flood the carburetor with an excessive amount of fuel through a solenoid switch triggered by the CDI box This type of rev limiter routes fuel from the return line hose back to the intake track 2 Prevent a spark from occurring at the spark plug This type of rev limiter is located in the igniter box and at a predetermined engine rpm grounds the ignition trigger circuit 36 Engine Overheating Limiter Watercraft and Snowmobiles Some watercraft have a feature that limits the engine rpm if the en gine temperature gets too hot When used this system limits the en gine rpm to approximately 3 500 through a temperature sensor that s located in the cooling system bypass hose and the CDI system Troubleshooting Symptoms The following is a list of common symptoms of trouble found on personal watercraft along with the most likely cause of the problem Troubleshooting Table PERSONAL WATERCRAFT Trouble Possible Problem Area Probable Cause Engine hard to start won t start or starts then immediately shuts off Outside carburetor Fuel line clogged or pinched Pulse line leaking or restricted Fuel filter plugged Fuel tap screens plugged Vent line restricted Fuel pump faulty Low engine compression Fuel cock not primarily operating to one fuel port Ret
40. main jet Figure 15 The purpose of this anti siphon valve is to prevent fuel from flowing through the high speed circuit during idle and at small throttle openings Fuel from the high speed jet passes through the inner venturi then into the engine The high speed adjuster controls the maximum amount of fuel flow for full throttle performance throttle to wide open throttle as Figure 15 illustrates Watercraft and Snowmobiles INLET PULSE LINE FUEL INLET LINE THROTTLE PLATE Kos BYPASS PORTS LOW SPEED OUTLET LOW SPEED ASSEMBLY ARM SPRING FUEL ma DIAPHRAGM AEH om Ul hy ati Sa A Ye a Ronde ADJUSTER W fi Ze iyan ZZ IA NEEDLE VALVE r cade CHECK VALVES FUEL PUMP foe lg FILTER FUEL RESTRICTOR 2r tZ a e A ree A NT VEN REGULATOR LOW SPEED AWNTI SIPHON CHAMBER flo ATMOSPHERE ARM DIAPHRAGM JET IDLE VALVE FUEL RETURN LINE INNER VENTURI HIGH SPEED ADJUSTER CLOSED HIGH SPEED MAIN JET INLET PULSE LINE FUEL INLET LINE 22224423 a DIAPHRAGM EEZ Ves Wy iY f CHECK VALVES ZII X FUEL PUMP NE THROTTLE PLATE BYPASS PORTS LOW SPEED OUTLET LOW SPEED ASSEMBLY ARM SPRING ADJUSTER D U o i NEEDLE VALVE if i a Se all ii FILTER FUEL RESTRICTOR N G d gt LN N UXTAIRZ aN m EA ILA VY SON TN FUEL VENT REGULATOR LOW SPEED ANTI SIPHON CHAMBER T
41. o see families out on a trail ride on their motorcycles one day on ATVs or even at the local lake with their personal watercraft the next During the winter months these same families can be found taking a ride on one of the many different snowmobiles that are available Throughout this study unit we ll divide these two popular types of recreational vehicles into separate subject areas First we ll discuss the snowmobile and then the personal watercraft Before categorizing the machines we ll begin with a brief history The History of Snowmobiles Although the snowmobile had been around for a number of years it didn t become popular until the mid 1960s During the mid 1960s the snowmobile market grew to over 125 different brands As the market became flooded with different types of machines ranging from single cylinder 50 cc engines to four cylinder 1000 cc racing machines the early 1970s saw a decline in the number of manufacturers In 1976 only ten snowmobile manufacturers remained Today there are only four major manufacturers of snowmobiles Arctic Cat Polaris Bombardier i Skidoo and Yamaha Although there are fewer manufacturers the snowmobile is still very popular A wide variety of snowmobiles are available ranging from the basic family machine to 150 horsepower racing machines Snow mobiles have evolved technically and become reliable sources of rec reation for millions of enthusiasts around the world Figure 1
42. of their snowmobile every few weeks instead of following proper storage procedures This is sometimes more harmful than ignoring storage procedures altogether because one of the major byproducts of the internal combustion process is water By starting the engine every few weeks even more harmful moisture enters the engine than if the fuel were just left in the tank over the summer Before putting a snow mobile away for the summer you need to fill the fuel tank completely and use a gasoline stabilizer to prevent the fuel from varnishing After adding conditioner to the fuel you should start the engine and run it long enough to allow the conditioner to reach the carburetor Internal engine storage preparation During extended periods of storage most manufacturers will recommend an engine storage pro cedure that involves spraying a type of oil into the engine through the carburetor to protect the internal engine components from moisture This procedure is known as engine fogging and must be performed in a well ventilated area On single cylinder engines you ll need to gain access to the mouth of the carburetor After the engine has warmed up and is running spray the manufacturer recommended pressurized fogging agent into the mouth of the carburetor for the specified amount of time Don t be surprised to see a lot of smoke coming out of the exhaust system This procedure must be performed intermittently to prevent the engine from sta
43. of these hoses is used for the cooling system and diverts some of the water coming through the pump to the exhaust manifold of the engine This is the hottest part of the engine and the water is used to cool the block during operation The other hose is used to siphon the water out of the watercraft hull and is known as the bilge system Watercraft Fuel Systems Personal watercraft use pressurized fuel systems Although they re vented to the atmosphere they use a one way check valve to main tain pressure when the engine is operating allowing the fuel system to function correctly Fuel Tanks The fuel tank is generally made of plastic and has a capacity of 4 to 15 gallons depending upon the size of the machine As stated below there are normally four separate lines that are attached to the personal watercraft fuel tank e The vent line which is easily identified by the one way check valve e The main fuel line which delivers the fuel to the carburetors when the fuel petcock is in the on position Watercraft and Snowmobiles e The reserve line which delivers the fuel to the carburetors when the fuel petcock is in the reserve position e The return line which returns the unused fuel that s flowing into the carburetors since they don t have float bowls Note There s one more line called the pulse line that s an indirect part of the fuel system The pulse line is used to operate the fuel pump diaphragm w
44. om the expansion cham ber the water then flows to the waterbox The waterbox is the main muffler on the craft On some models of personal watercraft cooling water is routed from the exhaust manifold to the flywheel cover and then to the expansion chamber In order to verify the movement of cooling system water you can see the bypass outlet which is tapped Watercraft and Snowmobiles 31 from the exhaust manifold On some models there are water jackets on the outside of the expansion chamber If there s a problem with the cooling system it results from a leak or a plugged passageway Bilge System The bilge system removes water from the engine compartment This is accomplished with negative pressure from the jet pump provided by a nozzle located at the pump through the breather which is the highest point in the system During normal operation the breather hole allows water to drain when the unit is shut off If it doesn t inspect the breather hole for blockage Drive System Personal watercraft use a direct drive system which makes the main tenance of these systems relatively easy The drive shaft is supported by a bearing housing and impeller housing Cavitation is the worst enemy of the drive system and is caused by water on the blade surface which is boiling from low pressure Most personal watercraft models use a self centering bearing housing which requires no shimming This design uses one bearing and four separate
45. on the engine Then we ll discuss non running checks which pertain to snowmobile chassis maintenance When you become a seasoned technician you ll be able to correctly perform these checks in less than one hour Running Checks Oil Injection Systems Most snowmobiles use an oil injection system If the model that you re maintaining has an oil injection system ensure that the oil tank is filled during the servicing procedure Watercraft and Snowmobiles Carburetor Adjustments In comparing motorcycle and snowmobile carburetor adjustments you ll find several similarities To adjust the carburetor s in a snow mobile begin by checking and adjusting the throttle play which you would perform in the same manner as on a motorcycle or ATV Specifications for play are found in the appropriate service manual Be sure to set the low speed mixture screw to the manufacturer s rec ommended initial setting which you can also find in the appropriate service manual If you have a snowmobile with multiple carburetors it s important that you verify that they re properly synchronized This is required for good performance and customer satisfaction After all other adjustments have been made set the idle speed to the speci fied setting and recheck the low speed mixture screw for proper adjustment Coolant Condition You ll also find similarities between motorcycles and snowmobiles when you re checking the condition of the coolant With liqu
46. oper operation of their machine to prolong the life of the V belt For example e Many snowmobilers like to stop on the incline of a hill and then accelerate uphill to feel the power and traction Just a few starts like this can ruin a V belt e Some new snowmobilers are uncomfortable when riding fast so they ride slower usually right at engagement speed This causes the clutches to constantly shift leading to belt slippage and fi nally belt failure Watercraft and Snowmobiles 13 Drive Chain and Sprockets The drive train and sprockets are two other areas you need to check and adjust when necessary The chain should have a predetermined amount of play specified by the individual manufacturer You need to check and adjust the chain tension inside of the chain case Rocking the secondary clutch back and forth after removing the V belt is an easy way to detect a loose or a tight chain Adjustments to the chain are made by moving the chain adjuster which is attached to the chain case Also check the chain case oil level to verify that the main seal and gasket are in good condition If the chain case oil level is low there s usually a problem with the main seal or gasket While working on this section of the snowmobile check the drive sprocket condition and alignment When drive sprockets are mis aligned or damaged they Il eventually cause track damage Perform this inspection while checking the track tension The snowmobile shoul
47. our answers with those on page 43 PERSONAL WATERCRAFT THEORY OF OPERATION The personal watercraft was patterned after jet drive boats which were first developed in the early 1960s Personal watercraft have a two stroke engine with a water cooling system that uses the water being ridden on as a coolant for the engine There are a few single cylinder machines but most watercraft engines are multiple cylinder designs that use two or three cylinders Current displacement ranges are from 500 cc to 1100 cc engines have horsepower ratings of 50 hp 18 Watercraft and Snowmobiles to over 120 hp All current watercraft use a fixed venturi carburetor system and most use one carburetor for each cylinder on the engine The induction systems used are reed valve and rotary valve designs Propulsion in a personal watercraft is fairly simple A jet pump brings in a tremendous amount of water from under the craft cycles it through a powerful rotating pump and then expels the water Two jet pump designs exist the axial flow and the mixed flow Personal Watercraft Power Train Figure 12 demonstrates a typical configuration of a watercraft power train The basic arrangement of the engine and jet pump are virtually identical for all manufacturers of personal watercraft The engine and driveshaft couplers connect the engine to the driveshaft There s no gear reduction Rubber dampers separate the couplers The driveshaft drives the impeller described
48. r storage Step One Preparing the Watercraft Before you begin preparing any watercraft for long term storage re view the storage procedures in the appropriate service manual and adhere to all warnings and cautions Ensure that you have all of the special tools and supplies specified in the service manual available to you This prevents interruptions and decreases the amount of time you ll need to perform the job Additional supplies you may need include the following items e A garden hose and an adapter with a inch or 7 inch fitting e An air compressor with an air blower nozzle e A siphon hose and hand pump e An appropriate container for draining fuel e A high quality multipurpose spray lubricant e Ahigh flashpoint solvent e Baking soda 38 Watercraft and Snowmobiles e Distilled water e A high quality wax e A high quality multipurpose grease and a grease gun e A pressure cable lubricator the same as used on motorcycles and ATVs e Anew set of spark plugs e Plenty of shop towels e A mat to set the watercraft on Step Two Preparing the Cooling System Personal watercraft manufacturers recommend starting the storage process by flushing sand and salt from the cooling system Often machines have cooling hose adapter fittings on the cylinder head that allow you to tap directly into the cooling system without removing any hoses Now the inch or inch adapter comes into play When flushing the cooling sys
49. ravity and a vertical line drawn through the displaced center of buoyancy Some watercraft hull designs contain a self circling feature which allows a watercraft to circle when a rider falls off When a rider falls the center of gravity shifts forward on the craft This causes the bow front to plow and a combination of the handlebar position idle rpm and asymmetrical water flow at the bow holds the craft in a circling motion 28 Watercraft and Snowmobiles Road Test 3 1 True or False All watercraft have charging systems that use a permanent magnet design 2 The water in the jet pump is brought in and discharged straight through the pump housing 3 The water in the jet pump is directed outward of the pump housing and then back to the center 4 Which jet pump design is more efficient for low rpm use 5 Which type of jet pump is best for high speed applications 6 Personal watercraft use the type of carburetor 7 How does an impeller on a personal watercraft differ from a propeller on a boat 8 If the fuel system used on a watercraft is pressurized how can there be ventilation to the atmosphere 9 A point at the intersection of two vertical lines one through the center of gravity and the other through the displaced center of buoyancy is called the Check your answers with those on page 43 PERSONAL WATERCRAFT MAINTENANCE Each personal watercraft service manual contains a periodic mainte
50. rmance use You ll also notice that many personal watercraft manufacturers are snowmobile manufacturers as well Watercraft and Snowmobiles 3 GAUGES REAR VIEW MIRROR FRONT STORAGE HANDLE BAR COMPARTMENT SEAT REMOVABLE FOR ENGINE ACCESS FIRE EXTINGUISHER UNDER REAR SEAT GAS CAP FOOT WELL NOZZLE GUARD RAIL SMALL STORAGE SPONSON COMPARTMENT FIGURE 2 A Typical Personal Watercraft Sit Down Model Image courtesy of Yamaha Motor Corporation U S A SNOWMOBILE THEORY OF OPERATION Unlike a motorcycle or ATV which uses a gear type transmission the modern snowmobile employs a two stroke engine that uses a variable centrifugal clutch system This system uses a primary centrifugal clutch which is mounted on the engine and a secondary clutch The primary and secondary clutches are attached by a V belt The secondary clutch is attached to a jackshaft arrangement which connects the transmission to the drive In short the jackshaft drives a set of gears inside a chain case This transfers the power to a drive shaft which turns the track The power flow of a snowmobile starts at the engine crankshaft and is transferred from the primary clutch to the secondary clutch by a belt The secondary clutch transfers this power to the jackshaft The jackshaft sends this power to the gears in the chain case Finally the drive shaft turns the snowmobile s track As you can see there are many moving components to this drive train We
51. rough and is inclined to the impeller axis Both lift and centrifugal force are applied to create a high pressure pump The impeller tip clearance is adjustable on the mixed flow jet pump In order to improve low rpm thrust adjust the impeller tip clearance On a mixed flow pump design shims are used on the drive shaft to move the impeller into the proper clearance range Check the tip clearance with a feeler gauge and adjust the shims as needed to get the proper specified clearance Note The jet pump used on a personal watercraft seldom needs any maintenance The impeller needs clearance verification and inspection for damage from debris entering the pump housing Personal Watercraft Driveshafts FIGURE 18 Reverse Gate Attachment of a Personal Watercraft Driveshafts are made in either one piece or two piece designs One piece designs are contained in the impeller housing and supported by a bushing An improperly aligned pump will damage the bushing in a one piece designed driveshaft A two piece driveshaft allows the pump assembly and impeller to be removed as one complete unit The impeller is screwed onto a secondary shaft which is supported by two bearings The main driveshaft contains splines that attach it to the impeller All pump housing mating surfaces must be properly sealed Reverse Some personal watercraft use a reverse gate attachment Figure 18 which allows the craft to be shifted into neutral and reverse These
52. ry To make sure the engine is level with the jackshaft place the tool at the bottom of the sheaves and do the same check If the alignment is off at the bottom shim the engine so that both alignment measurements are the same V Belt Adjustments In order to maintain proper clutch operation when performing main tenance you should also check the V belt V belt width Belts will wear with use and when the width of a belt is worn beyond the specified amount it must be replaced V belt width is measured with a Vernier caliper The manufacturer will have the specifications for the correct belt width in the appropriate service manual V belt length V belts must also be checked for proper length This is accomplished simply by using a measuring tape and measuring the belt after it has been removed from the clutches V belts can stretch and are no longer useful when they re stretched beyond their speci fied length V belt life There s no specific time or mileage at which the drive belt will wear out Length of belt service will depend on the type of use With proper maintenance care and correct operation a V belt should last for an average of 500 to 1000 miles It isn t uncommon however to see a V belt destroyed in only a few miles Usually this is due to improper operation or the conditions in which the snowmobile is be ing used It s a good habit for an experienced snowmobile technician to instruct novice snowmobilers on pr
53. s are prop erly installed on the fuel filter In addition to the one piece disposable filter some personal watercraft models have filter screens on the end of the fuel tank feed line This serves as a final precautionary measure to prevent dirt from entering the carburetor Some carburetors also incorporate a filter screen in the fuel supply circuit of the carburetor Electrical System Service The battery in a personal watercraft is used for the starter gages and trim adjustments It s virtually identical in design to a standard battery that s used on a motorcycle except for its ventilation system which uses a design similar to the maintenance free battery Most personal watercraft have a CDI type ignition system These systems may be AC or DC powered All of these systems use an electronic advance system that s built into the ignition The timing on these machines may be preset at the factory or can be set with a dial indicator and a timing light Normally the charging systems used on personal watercraft are the full wave permanent magnet type These charging systems may also be half wave or three phase systems The charging voltage should normally be within 13 15 VDC while the craft is at approximately throttle Personal watercraft use an electric starting system that contains a waterproof starter motor Conventional starters use a bendix system that requires no outside lubrication Rev limiters are used to protect the engine fro
54. tem follow the individual manufacturer s procedures to prevent water from backing up into the engine If this occurs major engine damage is likely to occur The general procedure to follow when flushing the cooling system on a personal watercraft is as follows 1 Attach the garden hose adapter to the proper fitting on the cylinder exhaust or cooling hose 2 Start the engine and let it idle 3 Turn on the water at the faucet and adjust the flow of water until it just begins to trickle out the bypass outlet on the side of the hull 4 Flush the cooling system for about five minutes 5 Turn off the water 6 Lift the rear of the craft about 8 10 inches and slightly rev the engine no longer than 15 seconds to expel the remaining water from the exhaust system 7 Stop the engine 8 After the engine has cooled off restart it and rev it again to en sure that all of the water has been removed from the exhaust Note Most service manuals will provide a procedure to remove the excess water using compressed air However several revs of the engine will remove the water from the exhaust and the heat will evaporate the remaining residual water Watercraft and Snowmobiles 39 Step Three Checking the Bilge Lines Attach the garden hose adapter to the bilge filter hose and run water through it for a minute or so flushing the bilge lines of any obstruc tions Water will accumulate in the engine compartment while you perform
55. the gears are rotat ing In a clutch type transmission however clutches can change ratios during operation by simply varying the diameter of the clutch pulley The V belt A V belt connects the primary and secondary clutches together A V belt is made of a rubber compound with a layer of braided synthetic cord running the entire length V belts provide a tremendous amount of flexibility and strength For added strength and protection both the inner and outer belt edges are covered with a fiber woven cloth that s bonded to the rubber You ll notice that the inner belt surface is ribbed which allows the belt to flex around the small primary clutch shaft The belt is also tapered from the outer to inner edge which helps concentrate the sheave pressure on the belt and to prevent belt slippage during normal operation The taper on the belt is necessary for proper clutch shifting Clutch size refers to the clutch diameter at the point where the V belt makes contact This is called usable clutch size The V belt follows a circular path around the curved inner surfaces of the sheaves As the sheaves close the V belt is forced outward into a larger diameter cir cle As the sheaves open the V belt drops in closer to the center of the clutch and runs in a smaller circle Figure 3 Watercraft and Snowmobiles FIGURE 3 The variable clutch system found on snowmobiles uses a V belt to connect the primary and secondary clutches Ima
56. urn line restricted Flame arresters plugged Choke improperly adjusted Fuel sediment bowl leaking Inside carburetor Diaphragm and or system dam aged or improperly adjusted Mixture screws improperly ad justed Water in carburetor Fuel passageways plugged Pop off pressure incorrect Engine misfires Fuel mixture too lean Mixture screws improperly adjusted Obstruction in fuel feed system Diaphragm and or system damaged or improperly adjusted Carburetor loose Pop off pressure too high Continued Watercraft and Snowmobiles 37 Troubleshooting Table Continued Engine misfires Fuel mixture too rich Mixture screws improperly adjusted Diaphragm needle tip damaged Choke on Flame arrester plugged Pop off pressure too low Engine won t idle but will accelerate Carburetor Mixture screw improperly adjusted Idle jet or port plugged Throttle plate loose or improperly adjusted Pop off pressure incorrect Engine won t accelerate but will idle Carburetor Mixture screw improperly adjusted High speed jet or port plugged Diaphragm and or system dam aged or improperly adjusted Choke on Personal Watercraft Storage Many personal watercraft owners depend on their local watercraft service department to prepare their machine for storage during the off season As a result you should become familiar with the steps for preparing a personal watercraft fo
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