Harley-Davidson Maintenance
Contents
1. A INTAKE STROKE B COMPRESSION C POWER STROKE D EXHAUST STROKE STROKE FIGURE 7 This illustration shows the four piston strokes in the sequence needed to complete one cycle of operation An engine runs by repeatedly completing this cycle Courtesy Kawasaki Motor Corp U S A Compression The compression stroke occurs as the piston moves upward in the cylinder and pressurizes the air and fuel mixture in the combustion chamber During this stroke both the intake and exhaust valves are in their closed position This process allows the upward movement of the piston to compress the trapped air and fuel mixture Power The power stroke occurs as the piston is moving downward again in the cylinder As the piston approaches TDC a spark plug is used to ignite the compressed air and fuel mixture This begins the power stroke As the air and fuel mixture burns it expands very quickly causing a tremendous amount of pressure and heat This pressure forces the piston down into the cylinder transmitting power to the crankshaft Exhaust The exhaust stroke takes place as the piston returns upward into the cylinder while the exhaust valve is open At this time the previously burned gases are pushed from the engine into the exhaust system This leaves the cylinder combustion chamber empty and prepares it for the start of another four stroke cycle 10 Harley Davidson Maintenance Each stroke of the four stro2. stood for competition hot and style became as important as speed The staggered short dual exhausts first seen in 1962 have become classic Sportster equipment Also developed during this modern period of design was the XR750 Harley Davidson s flat track racing engine Figure 4 Electric starting was introduced in 1965 on the Panhead which received rear suspension in 1953 And a motor known as the Shovelhead made its debut in 1966 The Shovelhead got its name because of the space in the center of the rocker box and because the rocker box looks like an upturned shovel This engine lasted 18 years until 1984 and was made in 76 and 80 cubic inch designs Harley Davidson introduced the Evolution engine design Figure 5 in the new Softail lineup for the 1984 model year The Evolution engine uses an aluminum alloy whereas past engine designs used primarily iron Harley Davidson Maintenance FIGURE 4 The XR750 was designed as Harley Davidson s flat track engine FIGURE 5 The Evolution engine was introduced in 1984 and is still used today In this study unit we ll discuss certain engine transmission and drive components that are specific to the V twin motorcycle Many areas of repair of the V twin motorcycle such as chassis brakes and electrical systems have already been covered in previous study units We ve repeated some of this information to serve as a review for you as you learn about som
3. Chain Driven Primary Drive The chain driven primary drive uses a chain and two sprockets Figure 21 to transfer power from the crankshaft to the clutch With a chain driven primary drive both sprockets turn in the same direction and use one of two different types of chain roller or Hy Vo Figure 22 The Hy Vo chain design is the most common type of primary drive because its design is stronger and quieter than the roller chain 32 Harley Davidson Maintenance FIGURE 21 The Chain Driven Primary Drive The chain type primary drive system found on the V twin motorcycle must be checked for proper adjustment on a regular basis There are normally two different chain play specifications one for a hot engine and one for a cold engine This is because of the expansion rate that s found in chains as well as how engine parts are affected by hot and cold temperatures The cold play specification is larger than the hot play specification You ll find that as a chain wears it stretches and generally has a tight spot at some point on the sprocket As a result you should always check for proper chain play at the tightest point of the chain You can adjust primary chain tension by using the plastic shoe that s located in the primary chain case The shoe is either raised to apply more tension or lowered to apply less tension on the chain This shoe can be seen on Figure 21 between the clutch and the crankshaft primary gear The chain type pr
4. so SoS oy Og ISS Primary Wet multiplate Riveted Belt primary chain case True Hy Vo cork paper False False Remove the spark plugs False If you find that the engine runs best at higher than one turn False Examination ONLINE EXAMINATION For the online exam you must use this EXAMINATION NUMBER 03302000 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
5. 20 show the main drive gear in a 4 speed direct drive transmission is attached directly to the clutch instead of the final drive sprocket or pulley as on the 5 speed system Neutral When the 4 speed direct drive transmission is in the neutral position the shift plate places the two sliding gears in a position so that their dogs can t engage with any dogs or slots on the gears adjacent to them If the clutch is engaged while the engine is running the countershaft rotates with the clutch Therefore the main shaft gear opposing the rotating countershaft gear main shaft 3rd freewheeling will rotate as well The final drive does not rotate in this transmission position Harley Davidson Maintenance 27 MAIN DRIVE GEAR TO FINAL TO MAIN SHAFT 10 FINAL DRIVE U 1 CT TIF nN ou A COUNTER SHAFT NEUTRAL FIRST GEAR FW S FW FX 3 6 SECOND GEAR THIRD GEAR K Da Eaa E A T i FW 5 FWJ O FOURTH GEAR FIGURE 20 This illustration shows a four speed direct drive transmission 28 Harley Davidson Maintenance First Gear When the transmission is shifted into first ge
6. Maintenance FIGURE 16 The piston is shown attached to the crankshaft connecting rod CRANKSHAFT CONNECTING X D Dry Sump Engine Lubrication System Most V twin motorcycles use a dry sump engine lubrication system The components in a typical dry sump lubrication system are the oil tank oil feed line oil pumps engine oil passageways and oil return line Figure 17 In this system an oil filter is attached to the engine to keep the oil that enters the engine as clean as possible In this type of lubrication system there are essentially two oil pumps One pump acts as an oil pressure feed and the other acts as an oil return pump Oil in the oil tank is gravity fed to the pressure feed side of the oil pump The pump forces oil through oil passageways in the engine The oil is under pressure and lubricates the internal moving engine components which would be otherwise damaged from the heat created by friction from the moving components Also the oil that s thrown off from pressure fed parts lubricates other internal engine components This method of lubrication is called splash lubrication The excess oil collects in the sump and returns to the oil storage tank via the oil return pump Harley Davidson Maintenance FIGURE 17 Compnents of a Dry Sump Four Stroke Engine Lubrication System Copyright by American Honda Motor Co Inc and reprinted with permission Iy OILSTRAINER SCREEN AND OR FILTER
7. a 004 inch play Aftermarket manufacturers make shims that allow you to set this clearance properly Just make certain that you keep the rocker arm centered over the valve stem while you shim out the excess play As long as you have the spark plugs out for the valve adjustment you should check their condition Sooty black plugs indicate a carburetion problem while plugs with rounded center electrodes are ready for replacement If your plugs are ready for replacement make sure to gap them according to the factory specification The gap should fall between 020 inch and 043 inch depending on the year and model you re servicing Also make sure you have the correct heat range Never replace the plugs found in the engine without checking whether or not the replacements are the correct type Always go by what the manual specifies Harley Davidson has been using Keihin carburetors for more than 12 years and these have proven easy to tune given the proper maintenance To begin the process warm the bike up to operating temperature Remove the air cleaner and check that the butterfly opens fully If it doesn t adjust the throttle cable After adjusting the throttle cable swing the handlebars from side to side to make sure there s sufficient free play The engine should maintain the set idle speed as the bars move from side to side Now find the idle mixture screw This is located on top of the carburetor under an aluminum anti tamper cap
8. drive system to the rear wheel Direct Drive Transmission Power Flow 5 Speed You should now have a basic understanding of the theory of operation of a direct drive transmission and its component parts Next we ll discuss the power flow in a 5 speed direct drive transmission Figure 19 24 Harley Davidson Maintenance COUNTERSHAFT DET O1 li eT MAIN DRIVE NEUTRAL FIRST GEAR FIREEWHEELING GEAR FIXED TO FINAL DRIVE SECOND GEAR THIRD GEAR Fane SS E E WHS F ee ES OUT IN 0 FOURTH GEAR FIFTH GEAR FIGURE 19 This illustration shows a five speed direct drive transmission Harley Davidson Maintenance Neutral When the 5 speed direct drive transmission is in the neutral position the shift drum places the sliding gears in a position so that the dogs on the sliding gears cannot engage with any dogs or slots on the gears adjacent to them If the clutch is engaged while the engine is running the two sliding gears on the main shaft 1st and 2nd will rotate with the clutch Thus the two countershaft gears opposing the rotating main shaft gears wil
9. high compression ratio may not be as powerful as it could be if it has a low volumetric efficiency This is because the cylinder isn t completely packed with a charge of air and fuel to create enough heat during compression The combustion process and engine performance are also affected by the size or displacement of the engine Engine displacement is determined by the diameter of the cylinder and the distance the piston moves when traveling from BDC to TDC The diameter of the engine cylinder is called the bore How far the piston travels from BDC to TDC is called the stroke By knowing the bore and stroke of a V twin motorcycle engine you can determine the engine s displacement For engine displacement examples or a more in depth explanation refer to your previous study unit entitled Motorcycle and ATV Engine Configurations Four Stroke Engine Operation As we ve also discussed in past study units there are four operations that are required for the engine to run They are intake compression power and exhaust Figure 7 Intake The intake stroke is the first downward movement of the piston while the intake valve is open At this time a fuel and air mixture is pulled into the combustion chamber The intake stroke takes place when the piston moves from TDC to BDC This creates a vacuum suction in the cylinder chamber which in turn draws air and fuel past the open intake valve Harley Davidson Maintenance 9
10. ratios by sliding shifting forks that move the gears into and out of mesh along the main shaft and countershaft Direct Drive Transmissions With a constant mesh direct drive transmission the power from the engine enters on one shaft and leaves on another shaft of the same axis As you probably remember constant mesh means that each gear on one shaft has a matching gear on the opposing shaft In other words the gears are meshed with each other at all times With a direct drive transmission top or high gear always has a ratio of 1 1 hence the name direct drive This type of transmission was widely used on older European motorcycles as with many older and current V twin motorcycles Harley Davidson Maintenance 21 Direct Drive Transmission Components Although we ve discussed most of these items in previous study units it s important for you to know about each of the components of a transmission so we ll review this information next Fixed Gears Fixed gears can t move on the shaft to which they re attached These gears will be attached to a shaft in one of three ways machined as part of the shaft splined to the shaft or pressed onto the shaft A fixed gear always rotates at the same speed as the shaft it s attached to In a diagram or in text fixed gears are normally abbreviated as EX Sliding Gears Sliding gears slide across the axis of the shaft to which they re attached Since sliding gears are s
11. that must be removed before the idle mixture can be adjusted Drill a 1 8 hole in it and thread a sheet metal screw into the hole Use the sheet metal screw to pull out the anti tamper cap Be careful you don t drill the hole too deeply or you ll damage the idle mixture screw To prevent this from happening wrap a piece of tape around the drill bit 100 inch from the end of the bit The position of the tape will indicate when you ve drilled deeply enough Turn the idle mixture screw in or out until you achieve the highest idle If the idle speed creeps above the speed listed in the manual reset it with the idle stop screw and readjust the mixture screw You ll know that you ve set the mixture screw properly if the idle speed drops when you turn the mixture screw in and out from your setting The correct setting should be very close to the one listed in the manual somewhere between a half turn and 1 1 turns out If you find that the 44 Oil Levels Chassis Harley Davidson Maintenance engine runs best with the mixture screw set at less than a half turn then the idle jet is too large If you find the opposite is true then the idle jet is too small Of course this will be the case only if the engine has been modified from stock or if there s some problem with it such as bad rings or valves that aren t seating properly Replace the anti tamper cap with a new one when you re finished with the carburetor Drive it in car
12. 5 single cylinder two stroke engine came out however the bike never completely fulfilled the lightweight demands of Harley Davidson dealers The panhead engine design Figure 3 was first produced for the 1948 model year It superseded the Knucklehead because of its lighter weight increased power and better oil passage The knucklehead engine design was all iron whereas the panhead engine design produced through 1965 had numerous aluminum top end parts The Panhead got its name because of the shape of the rocker covers which resemble a pan In 1949 the Hydra Glide fork was introduced This was a hydraulically dampened telescopic fork FIGURE 3 The Panhead engine superseded the Knucklehead engine because of its light weight power and better oiling system Harley Davidson Maintenance The Modern Years 1950 Today The Harley Davidson model K was introduced in 1952 This model featured rear suspension and a combination foot shift and hand clutch This model is considered the father of the Sportster The Sportster was introduced in 1957 and was successful beyond the manufacturer s wildest dreams Larger by 10 cubic inches than the original model K the 55 cubic inch machine boasted overhead valves In only its second year of production an increase in performance was obtained through higher compression larger valves and aluminum tappets The Sportster set the stage for the XLCH model Some say that the CH in XLCH
13. DSON MOTOR COMPANY 1 The Early Years 1903 1929 The Middle Years 1930 1949 The Modern Years 1950 Today V TWIN MOTORCYCLE ENGINE DESIGN 6 Four Stroke Engine Combustion Four Stroke Engine Operation Four Stroke Engine Components Dry Sump Engine Lubrication System Carburetors V TWIN MOTORCYCLE DIRECT DRIVE TRANSMISSIONS 20 Direct Drive Transmissions Direct Drive Transmission Components Direct Drive Transmission Theory of Operation Direct Drive Transmission Power Flow 5 Speed Direct Drive Transmission Power Flow 4 Speed Transmission Problem Symptoms V TWIN MOTORCYCLE DRIVE SYSTEMS 6 31 Primary Drives Clutch System Final Drives V TWIN MAINTENANCE 2c e oS OE ea Ye ee Se SS 42 Spark Plugs Carburetor Oil Levels Chassis ROAD TES ANSWERS 62 ie ee ee ea ele Ae ee x 47 EXAMINATION pra ge a eae eee ER cea eA Le eae 49 Harley Davidson Maintenance INTRODUCTION The American V twin motorcycle has been around for a long time since the early 1900s and includes many different brands Because of their popularity when most people hear the words American V twin they automatically assume that you re referring to a Harley Davidson motorcycle There are however a variety of foreign manufacturers building V twins in the United States such as Honda and Kawasaki as well as American companies such as Polaris In this study unit we ll discuss many of the a
14. OIL FEED LINE OIL PUMPS Advantages One advantage of the dry sump lubrication system is that the engines that use this system give the oil a better place to cool because they store the oil in a separate storage tank away from the hot engine An anti leak check valve prevents the oil in the oil tank from leaking back to the sump and filling it with oil What would happen if this check valve were to malfunction A condition called wet sumping would occur If the oil in the oil tank fills the engine sump it would cause the engine to smoke excessively possibly to the point of damaging the spark plugs Such problems occur because engine crankcases aren t designed to contain large amounts of oil This is why dry sump systems have separate storage tanks for the oil Lubrication System Maintenance Changing the oil and oil filter on a regular basis is the only maintenance required in a dry sump lubrication system The general steps used to prepare the motorcycle for an oil change change the oil and change the filter are 18 Carburetors Harley Davidson Maintenance Run the engine until its normal engine temperature is obtained Remove the drain plug that s attached to the oil tank or oil tank drain hose and let the oil completely drain from the oil tank into an approved container 3 Carefully remove and discard the oil filter 10 11 12 13 Use a clean lint free cloth shop rag to clean the area around where the filter
15. Study Unit Harley Davidson Maintenance By Ed Abdo About the Author Edward Abdo has been actively involved in the motorcycle and ATV industry for over 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 In this study unit you ll learn about the engine design drive system and maintenance procedures as they pertain to the Harley Davidson V twin motorcycle Included in this study unit is a brief history of this motorcycle and an explanation of the current basic engine design primary drive clutch and final drive system Also included is a section covering the transmissions found on this increasingly popular motorcycle When you complete this study unit you ll be able to e Identify the different engine designs used by Harley Davidson e Identify the engine components specific to the V twin engine e Describe how the direct drive transmission operates on the V twin motorcycle e Understand how the drive systems operate on the V twin motorcycle INTRODUCTION os raa SRA SSR We Oe eS 1 HISTORY OF THE HARLEY DAVI
16. ar the shift plate slides the shift fork which is attached to the countershaft sliding 3rd gear into freewheeling 1st gear on the countershaft Since 1st gear on the main shaft is fixed to the final drive this motion attaches the clutch and main drive gear through the countershaft to the final drive This allows power to flow to the rear wheel by delivering power to the final drive sprocket or pulley Second Gear When the transmission is shifted into second gear the shift plate must slide the countershaft sliding 3rd gear out of the countershaft freewheeling 1st gear and into countershaft freewheeling 2nd gear This attaches the countershaft to the final drive as the main shaft 2nd gear is a sliding gear Once again the transmission is fully engaged except that it s now at a slightly higher gear ratio Third Gear When the transmission is shifted into third gear the shift plate must do two things at one time just as the 5 speed shift drum did earlier Second gear must be disengaged by moving the countershaft sliding 3rd gear away from countershaft freewheeling 2nd gear while at the same time the main shaft sliding 2nd gear is slid into the main shaft freewheeling 3rd gear Since 3rd gear on the countershaft is a sliding gear this again attaches the final drive and countershaft but now in the third gear position Fourth Gear To shift into fourth gear the sliding 2nd gear on the main shaft must be disengaged from the main sha
17. ase in velocity and a drop in pressure To review how carburetors operate refer to your study unit on Fuel Systems Harley Davidson Maintenance 19 CV Carburetor Operation The modern V twin motorcycle uses a constant velocity CV carburetor which is usually gravity fed CV carburetors use a fuel enrichment system for cold starting The CV carburetor on most of these machines is equipped with an accelerator pump The accelerator pump system uses sudden throttle openings to quickly inject fuel into the carburetor venturi This provides extra fuel for smoother acceleration CV Carburetor Adjustments Since the V twin motorcycle uses only one carburetor to feed the air and fuel mixture into the engine external adjustments include only an idle adjustment The idle adjustment entails adjusting a simple external adjusting screw The low speed fuel mixture screw is preset and shouldn t be tampered with once it has been properly set to the manufacturer s specification which can be found in the appropriate service manual Road Test 1 At the end of each section of Harley Davidson Maintenance 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 1now 1 The combustion in a four stroke engine changes energy into energy 2 Most air cooled V twin motorcycles use a an sump lu
18. ater V twins used mechanically operated spring valves 2 Harley Davidson Maintenance In 1912 the first chain driven model Harley Davidson was offered In 1915 the company introduced the first 3 speed transmission as well as the first Harley with a headlight The 1920 Harley Davidson sport model had a horizontally opposed twin cylinder engine similar to the BMW Boxer This engine boasted 584 cc of displacement and came with a fully enclosed chain drive system In 1922 two new V twin engines were introduced the 986 and 1208 cc In 1926 a 348 cc single cylinder overhead valve engine was introduced This engine had a 73 mm bore and 82 5 mm stroke A special overhead valve speedway racing model called the Peashooter was also introduced in 1926 The longest running in production years Harley Davidson engine design was the 45 cubic inch twin cylinder Flathead Figure 1 This engine was built between 1929 and 1974 When the company offered three different 45 cubic inch models in 1929 it indicated that they were serious about this bike This engine model was called the Flathead because there were no moving parts in the head the moving parts were all in the cylinder block This engine design is widely known as a side valve engine design FIGURE 1 The Flathead engine has no moving parts in the head The Flathead was built for 45 consecutive years making it the longest produced American made motorcycle engine The Mi
19. attaches Lubricate the gasket of a new oil filter with the same engine oil that you ll be using to fill the oil tank Reinstall the oil filter onto the engine Be sure to tighten the oil filter to the manufacturer s specifications usually to 4 turn after the gasket surface makes contact with the filter mounting surface Reinstall the oil tank drain plug and tighten properly Pour the specified amount of engine oil into the oil tank The manufacturer will have suggestions for the type of oil that should be used in the engine for different weather and riding conditions This information can be found in the model s service or owner s manual Start the engine and carefully check for oil leaks at all points of the oiling system where components were removed and replaced Run the engine to allow it to warm up Turn off the engine and add oil to the tank With the motorcycle in the upright position check the oil level and add oil to the tank if the engine oil dipstick shows that the oil level is low Be sure to avoid overfilling the oil supply tank The tank requires air space for heat expansion as the oil heats up The carburetor is positioned between the intake valve and the air filter You ve learned that basic carburetor operation occurs because of the negative pressure that results from the downward motion of the piston during the intake stroke As the air passes through the carburetor venturi the venturi creates an incre
20. between toothed pulleys Clutch System Harley Davidson Maintenance GILMER TYPE BELT The purpose of a clutch is to engage and disengage the power flow from the crankshaft to the transmission to start stop and shift transmission gears The clutch used on the typical V twin motorcycle is part of the primary drive system The clutch is a wet multiplate manual clutch or dry multiplate manual clutch if it s used with a belt driven system The clutch also has steel and fiber friction plates that are set alternately in the clutch outer shell The clutch is located in the primary side case which contains the lubricant for the wet clutch The friction plates in the clutch are made of a cork or paper based material depending on the model and year and are designed to drive the clutch outer shell The steel plates are splined to the clutch hub which is splined to the transmission and uses a left hand threaded nut to attach it to the shaft Usually different steel plates are required for different types of friction plate materials The steel plates should be used for the proper application as described by the appropriate service manual The steel plates are called the drive plates while the friction plates are known as the driven plates Harley Davidson Maintenance 35 The clutch outer shell is made up of pieces riveted together that contain the outer shell the primary drive sprocket and the electric starter gear Some model
21. brication system 3 The three phases of the internal combustion process in their order of occurrence are j and 4 A An______ prevents oil drainage from the oil tank back into the engine 5 Fuel is fed to the V twin motorcycle carburetor 6 The modern V twin motorcycle uses a type carburetor Continued 20 Harley Davidson Maintenance Road Test 1 7 True or False By increasing the compression ratio of an engine you ll usually increase the power output 8 The four strokes of the engine used in the American V twin in order of occurrence are y and Check your answers with those on page 47 V TWIN MOTORCYCLE DIRECT DRIVE TRANSMISSIONS This section of your study unit provides you with information specific to V twin motorcycle transmissions We ll also review some general information on transmissions including theory of operation component identification and direct drive power flow A transmission gives us the ability to shift gears which allows for increases in rear wheel speed without overworking the engine Both 4 speed and 5 speed V twin motorcycles use a direct drive transmission system A direct drive 4 speed or 5 speed transmission case contains a series of gears on different shafts which are powered by the engine primary drive system The transmission in this style of motorcycle may be separate from or combined with the engine assembly A gear shifter is used to shift the transmission into the desired
22. ch are used to guide the shift forks whereas the shift drum is a round drum Harley Davidson Maintenance FIGURE 18 The 4 speed direct drive transmission uses a cam plate to move the shifting forks to engage and disengage the transmission 23 Direct Drive Transmission Theory of Operation With a direct drive transmission the rear wheel rotates in the same direction as the engine when a primary chain or belt is used To accomplish this the transmission must allow the power from the engine to come into one shaft make any necessary gear ratio changes and then transmit the power to the rear wheel without reversing rotation This is the purpose of direct drive transmissions In a direct drive transmission the power from the engine enters on the main shaft from the primary drive and is transferred to the countershaft which determines the gear ratio for the lower gears The power is transferred from the countershaft through the main drive gear which directs the power through the main shaft The drive sprocket is splined to the main drive gear which as mentioned earlier fits on the main shaft The drive sprocket rides on bearings on the 5 speed direct drive transmission On the 4 speed system the drive sprocket is attached directly to the main shaft In top gear the main shaft is directly connected to the main drive gear and power doesn t flow through the countershaft Instead power flows directly from the engine s primary
23. ddle Years 1930 1949 In the 1930s the flathead engine design was so popular and successful that the company offered it in a larger displacement the 74 cubic inch 1200 cc engine The year 1936 brought to the motorcycling world an engine that used a valve rocker box This 61 cubic inch engine design looked like knuckles and was nicknamed Knucklehead Figure 2 The Knucklehead was Harley Davidson s first overhead valve twin cylinder engine and was so successful that its basic concept still serves Harley Davidson today with the Evolution engine Harley Davidson Maintenance FIGURE 2 The knuckle head engine has a valve rocker box on the engine that looks like knuckles This was Harley Davidson s first overhead valve V twin cylinder engine From 1936 to 1941 an 80 cubic inch side valve twin engine was also produced The factory recommended this engine initially designated the ULH for sidecar work The company decided not to continue this model after World War II most likely because of the popularity of the Knucklehead A 74 cubic inch overhead valve engine was introduced in 1941 and was identical apart from its displacement to the highly popular 61 cubic inch model The 74 cubic inch model was produced in limited quantities during World War II and in only slightly larger batches in 1946 and 1947 After the war the side valve engines were replaced by a new 1206 cc overhead valve engine In 1947 anew 12
24. e countershaft is a sliding gear this again attaches the main shaft and countershaft but now in the third gear position This drives the final drive through the countershaft 5th gear and out the main drive gear 26 Harley Davidson Maintenance Fourth Gear When the transmission is shifted into 4th gear the sliding 2nd gear on the main shaft is disengaged from the main shaft freewheeling 3rd gear just as the main shaft 1st sliding gear attaches itself to the main shaft freewheeling 4th gear Countershaft 4th gear is a fixed gear and the countershaft and main shaft complete the power flow once again to the main drive gear Fifth Gear For our final gear the main shaft sliding 1st gear is disengaged from main shaft 4th gear while the sliding 2nd gear on the main shaft is slid into the main drive gear This in turn connects the main drive gear directly to the main shaft which allows power to be delivered directly from the clutch attached to the main shaft to the final drive pulley Direct Drive Transmission Power Flow 4 Speed Many V twins also use a 4 speed direct drive transmission which is similar in design to a 5 speed but has some operating differences Next we ll explain the power flow of the 4 speed transmission One of the differences between the 4 and 5 speed direct drive transmission is that the 4 speed only needs two sliding gears as opposed to the 5 speed which needs three sliding gears Also as Figure 19 and Figure
25. e of wet sumping is a bad check ball After you ve serviced the engine it s time to address the chassis We ve already talked about adjusting the final drive chain or belt but you ll also need to check the brake pads for wear Any pad worn unevenly or down to the wear indicators must be replaced immediately If the bike has hydraulic brakes the fluid must be checked Replace the fluid if it has been two years or longer since the last change or simply top it off if the fluid is still clear Be careful what kind of fluid you re adding Some types aren t compatible Check with the owner of the Harley Davidson Maintenance 45 bike if you re in doubt Failure to do so will necessitate a complete tear down of the braking system Go over the rest of the bike The cables should be lubed with a light oil such as ATF or 3 In 1 their free play should also be set to factory specifications Check for frayed cables especially at the levers In addition remove and lube the pivot bolts from the clutch and brake levers You can improve the shifting dramatically with this simple exercise The tires should be checked next as you pay special attention to the wear bars molded into the tread If the wear bars are flush with the surface of the tire then the tire is ready for replacement Tire pressures are listed in the owner s manual and should be strictly adhered to If the bike you re servicing has tires other than those it came w
26. e of the specific engine and transmission features found on the V twin motorcycle Harley Davidson Maintenance V TWIN MOTORCYCLE ENGINE DESIGN An air cooled four stroke V twin motorcycle engine Figure 6 is a group of assembled parts that are designed to change heat energy the burning of fuel into useful mechanical energy the movement of the motorcycle In other words the engine provides the power that s needed to turn the rear wheel of the motorcycle Although we ve discussed it in an earlier study unit it s important that you know and understand the principles of how the four stroke internal combustion engine operates so that you can become a good motorcycle technician Knowing this information will give you a better understanding of why the motorcycle engine performs the way it does FIGURE 6 This picture shows some of the many components that make up a four stroke air cooled V twin motorcycle engine Four Stroke Engine Combustion As we ve mentioned the combustion of the four stroke engine changes chemical energy into heat energy This is done by compressing the air and fuel mixture into a small space and by taking advantage of its expansion as it s heated The air and fuel mixture is compressed by the piston and ignited by a spark plug which burns the air and fuel mixture This burning is known as rapid oxidation and is actually a chemical reaction that takes place very quickly During this process the fu
27. e them last their full life The drive chain requires service more often than any of the other final drive components The correct adjustment and proper lubrication of the drive chain will help prolong the life of the chain and sprockets Chains need frequent lubrication because they move at high speed and transmit the power of the engine Heat builds up from the friction of the chain moving over the sprockets Lubrication is needed to help reduce the friction and heat When properly lubricated the life of the chain and sprocket will be extended As we ve discussed previously the chains used on chain final drive systems are composed of pin links and roller links Pin links are composed of two plates and two pins while roller links are composed of two plates two bushings and two rollers The links are connected together by a master link or are considered to be an endless chain with no master link Most chains used on V twin motorcycles are O ring chains that use O rings between the bushings and plates to help protect the chain and to keep lubrication inside the roller The sprockets on chain final drive systems are flat metal plates with teeth around the outside edges The chain fits around the sprocket with the teeth of each sprocket fitting into the open spaces between the rollers of the chain Worn sprockets will ruin a chain Sprocket wear is visible and the condition of a sprocket can be judged by comparing it to a new one Harley Davidso
28. ed to the valve by the push rod Figure 14 and rocker arm When the tappets are functioning properly the assembly operates with minimal tappet clearance The units automatically compensate for heat expansion to maintain a zero clearance condition m A FIGURE 13 A V twin Engine Rocker Arm FIGURE 14 The push rod has an adjuster built into it for finer adjustments to the hydraulic valve lifter system Harley Davidson Maintenance Harley Davidson Maintenance 15 Engine Crankcases and Crankshaft The gear case is located behind the timing cover on the right side of a V twin motorcycle engine crankcase assembly The gear case contains a series of gears which transmit engine power to the camshaft ignition timing device and to the oil pump Figure 15 shows a cutaway view of a V twin engine that shows this area in greater detail This area of the crankcase is lubricated with engine oil through a breather valve from the engine crankcase The vertically split crankcase supports the crankshaft cylinders and cylinder head assemblies The crankshaft changes the reciprocating up and down motion of the piston into rotating motion which turns the gears to produce movement of the motorcycle The piston is connected to the crankshaft by the wrist pin and connecting rod Figure 16 FIGURE 15 This cutaway view shows some of the gears and engine components found in the gear case of a V twin engine 16 Harley Davidson
29. efully with a small ball peen hammer Also the air filter should be replaced if it s excessively dirty Filters usually last for about 10 000 miles but this figure varies according to riding conditions If the bike is operated on dirt roads the filter should be replaced more often Harley Davidson makes an excellent replacement filter kit under the Screamin Eagle name This filter is made of oil pleated paper and catches dirt particles as small as five microns in size Filters actually work better once they re a little dirty and they can be washed and reused several times The Harley Davidson engine is much more sensitive to dirty oil than an automobile engine HD engines contain rolling element bearings in the crank train and dirt can ruin these bearings in short order A car has plain bearings and dirt often embeds itself in the soft bearing material without harming the journal For this reason Harley Davidson engines should receive frequent oil and filter changes The oil should be changed every 2 000 miles while the filter should be with every oil change If you drain the oil and find that there s more than a quart in the crankcase this is a signal that the oil pump has a bad check valve The Harley Davidson engine is of a dry sump design and as such contains an oil pump that draws oil out of the crankcase and back into the oil tank Excess oil in the crankcase results in smoking and plug fouling The most common caus
30. el and oxygen in the air combine to form new Harley Davidson Maintenance molecules These combustion molecules are carbon dioxide CO and water H O While the fuel and oxygen molecules are converting they lose some of their internal energy This energy is released as heat This heat then causes an increase in the pressure inside the cylinder s combustion chamber which then forces the piston downward There are three phases involved in the internal engine combustion process combustion lag active combustion and post combustion Combustion Lag The first phase of combustion occurs as the piston compresses the air and fuel mixture During this compression the spark plug ignites a small portion of the air and fuel mixture and a ball of fire spreads outward and begins to consume the remaining mixture The burning inside the cylinder is a chain reaction that spreads throughout the combustion chamber Before the chain reaction is completed there s a short period of slow burning in the combustion chamber This slow burning process is known as combustion lag Active Combustion The second phase of combustion occurs as the initial lag is overcome and the chain reaction begins to speed outward in the combustion chamber A rapid temperature and pressure build up occurs as the charge is consumed The chain reaction of burning molecules accelerates and the chemical conversion causes heat to be quickly released This increase in heat causes
31. en the chain and counterclockwise to loosen the chain Be sure to turn each adjusting nut an equal number of turns to keep the rear wheel in proper alignment with the chain The rear axle must remain parallel with the swing arm pivot shaft When you have completed the adjustment of the chain tighten the axle nut to the manufacturer s specified torque If the chain adjusters have reached their limit proper chain adjustment can no longer be achieved and the chain will need to be replaced Belt Final Drives Belt final drive systems are used on many Harley Davidson and other brands of V twin motorcycles As we mentioned earlier in this study unit these systems use a Gilmer type belt that has teeth molded into it which mesh with a pair of toothed pulleys The belt requires no lubrication and must be kept clean and dry This system has certain maintenance requirements including proper alignment of the belt and pulleys and proper belt tension which is extremely critical with this type of final drive system To adjust the belt first loosen the rear axle nut and after loosening the jam nuts turn the belt adjuster bolts as needed to move the axle in or out As with the chain final drive turn each adjuster nut an equal number of turns to keep the wheel properly aligned To move the axle forward loosen the adjuster nuts an equal number of turns and tap Harley Davidson Maintenance 41 10 lightly on the ends of the adjuster studs using a s
32. erial that was presented in the study unit Clutches Transmissions and Drives Clutch disengaged When the clutch lever is pulled the clutch push rod pushes against the clutch lifter rod The clutch lifter applies pressure to the clutch pressure plate resulting in a gap between the clutch discs and clutch plates This separates the power of the crankshaft from the rear wheel 38 Final Drives Harley Davidson Maintenance Clutch engaged When the transmission is shifted into gear and the clutch lever is gradually released the discs and plates become caught between the pressure plate and the clutch center This now prevents the clutch from slipping and the power of the crankshaft is again completely transmitted to the rear wheel There are two common final drive systems used on V twin motorcycles chain and belt Chain Final Drives The chain driven final drive system is commonly found on V twin motorcycles As we discussed in earlier study units a chain driven final drive consists of two sprockets One sprocket is attached to the output shaft of the transmission and one is attached to the rear wheel A chain is used to connect the sprockets With a chain driven final drive system you can replace the sprockets with other different sized sprockets to provide a wide range of gear ratios The sprockets and chain in a chain driven system wear out over time As a result you ll need to frequently perform maintenance if you are to mak
33. f aluminum with a liner of cast iron or steel that s poured into the cylinder Figure 11 These liners have a cylinder finish that s designed to create a good piston ring seal while providing sufficient oil for lubrication FIGURE 11 An aluminum cylinder has a liner made of cast iron or steel Harley Davidson Maintenance FIGURE 12 Two different V twin pistons are shown here The pistons have pockets machined into them to prevent contact with the valves 13 Pistons and Rings In a properly sized cylinder the piston fits snugly and transfers combustion power directly to the connecting rod and indirectly to the crankshaft The typical Harley Davidson pistons have valve pockets machined in the top to provide adequate clearance for the intake and exhaust valves to open Figure 12 The piston rings in the V twin four stroke engine perform two important functions they seal the cylinder to trap the power of combustion and prevent the oil that s used to lubricate the piston from entering the combustion chamber Rocker Arms Valve Train Rocker arms Figure 13 are used to open the intake and exhaust valves The valve tappet and guide assembly consist of a tappet and roller The hydraulic tappet contains a plunger and cylinder plus a check valve which allows the unit to pump itself full of engine oil to take up any excess clearance in the valve train The up and down motion produced by the revolving cam is transmitt
34. found in Japanese bikes Use lithium grease to lube these bearings Heavy wheel bearing grease will be squeezed out of the rollers as they rotate However make sure the bearing spacer is set correctly A dial indicator set on the end of the axle in the front wheel should indicate 004 018 of axial play If that s not the measurement you get you ll need to select one of three different sized bearing spacers available from Harley Davidson 46 Harley Davidson Maintenance You ve now completed a thorough maintenance check of a typical American V twin motorcycle Proper maintenance is essential in keeping any bike running well It also contributes to the safety of the rider Poorly maintained bikes are accidents waiting to happen Road Test 4 1 What s the first step in setting valve clearance 2 True or False Spark plugs with square shaped center electrodes should be replaced 3 What signifies that the idle jet is too small 4 True or False Filters only work well when they re completely clean Check your answers with those on page 47 2 Oy eo SI ey eu Wg ES Road Test Answers chemical heat Dry combustion lag active combustion and post combustion anti leak check valve Gravity Constant Velocity CV True intake compression power exhaust Engine False Five Four All gears within the transmission have a mate on the opposite shaft Sliding gear Bearing The clutch ji
35. ft freewheeling 3rd gear and slide into the main drive gear This in turn connects the main drive gear directly to the main shaft which allows power to be delivered directly from the clutch to the final drive pulley or sprocket Transmission Problem Symptoms Since each part in the transmission does a certain job when a failure occurs you can usually tell which part is at fault by the symptoms Here are some common malfunctions of a transmission and how you can recognize them Harley Davidson Maintenance Difficult Shifting When excessive clutch lever pressure is required to shift gears it may indicate either a clutch problem or a transmission problem If the clutch is at fault the symptom of grinding gears when shifting into low or first gear will be evident In most cases if the clutch is at fault a simple adjustment may solve the problem When difficult shifting occurs between other gears while the motorcycle is moving it s usually caused by a bent shift fork When a shift fork has been damaged it no longer fits properly in the grooves of the gear This problem requires disassembly of the transmission and replacement of the shift fork Difficult shifting can also be caused by a partially seized gear on a transmission shaft This problem is generally caused by the lack of proper lubrication and as with the shift fork disassembly of the transmission is required to repair this type of condition Inability to Shift Gears Someti
36. hed to the main shaft Harley Davidson Maintenance 4 speed main drive gear In the 4 speed transmission the main drive gear is attached directly to the clutch and slides over the main shaft As with its 5 speed counterpart when the transmission is in any gear other than fourth top gear the main drive gear is driven by a gear on the countershaft Main Shaft The main shaft in a direct drive transmission is connected to the clutch Both rotate at the same speed The main shaft rotates whenever the engine is running and the clutch is engaged Countershaft The countershaft is used to transfer the power coming into the main shaft to the main drive gear The countershaft rotates only when the transmission is engaged and rotates at the speed that the engaged gear set ratio permits Shift Drum The shift drum controls the movement of sliding gears using shift forks The shift forks have pins that set into grooves The grooves are machined into the drum and allow the gears to slide from side to side to move them into and out of transmission engagement The shift drum is rotated by a shifting mechanism that s operated by a shift lever on the left side of the motorcycle Cam Plate A cam plate Figure 18 is used on 4 speed direct drive transmissions This plate operates under the same principle as the shift drum The difference between a cam plate and a shift drum is that the cam plate is a flat plate with grooves machined into it whi
37. imary drive must be kept well lubricated for proper operation On the V twin lubrication is usually applied via the transmission Harley Davidson Maintenance 33 FIGURE 22 Roller and Hy Vo primary drive chains are shown here o Oz ROLLER CHAIN HY VO CHAIN Belt Driven Primary Drives The belt driven primary drive system uses a toothed belt called a Gilmer type belt and two pulleys with teeth attached to them Figure 23 Just like the chain driven primary drive system the belt driven type of drive has both pulleys turning in the same direction This type of primary drive because it uses a belt is much quieter than gear driven or chain driven primary drives Unlike the other primary drive systems however the belt primary drive arrangement must be kept dry and therefore uses a dry clutch The adjustment for this type of primary drive is very critical for proper operation If the belt is too loose it will seem like there s excessive play in the drive train and it will make excessive noise in the primary belt area If the belt is too tight the clutch will drag Primary belt adjustment is accomplished by loosening the transmission mounting plate and prying on the crankcases with a heavy duty screwdriver to increase the belt tension While you re holding the screwdriver in place to maintain proper tension tighten the transmission mounting bolts 34 FIGURE 23 A Glimer type belt has teeth in it and attaches
38. inder head is heavier than the aluminum cylinder head 11 Cylinder Heads Cylinder heads on the typical V twin engine may be made of cast iron or aluminum Figure 9 The V twin engine cylinder heads that are made today are made of aluminum Air is used to cool the cylinder heads These heads have large fins that aid in heat dissipation Modern Harley Davidson cylinder head designs use both a round combustion chamber as well as an egg shaped chamber Figure 10 As we discussed in an earlier study unit cylinder heads are designed to e Create sufficient turbulence within the combustion chamber The shape of the combustion chamber creates turbulence Turbulence is essential to keep the air and fuel mixture well atomized which is needed to complete combustion e Create a squish area Within the combustion chamber the squish area also helps create turbulence and forces the combustible mixture towards the spark plug which increases the efficiency of the engine e Eliminate restrictions when the air and fuel flows through valve ports CAST IRON ALUMINUM CYLINDER HEAD CYLINDER HEAD 12 FIGURE 10 This photo shows two different com bustion chamber designs used in V twin air cooled engines The egg shaped chamber is more efficient than the round chamber because the shape helps force the fuel charge into the spark plug area Harley Davidson Maintenance Cylinders The modern V twin cylinder assembly is usually made o
39. ith you can find the recommended pressures from the manufacturer The factory recommended tire pressures generally apply for aftermarket tires as well The level in the battery is very important and any chassis tune up is incomplete without a battery servicing Replace the electrolyte with distilled water You may want to test the specific gravity with a hydrometer for a more complete picture of the battery condition As you ll remember from past study units the proper specific gravity should be between 1 275 and 1 30 By virtue of their 45 V twin engines Harley Davidson engines vibrate This vibration causes bolts and nuts to loosen over time Go over all external fasteners and check to see that they re properly torqued A thread locking compound is very useful in keeping bolts tight that frequently become loose Make sure you thoroughly clean the threads of any bolt you treat with thread locker this will help it perform properly Now check the fork seals for leakage Fork oil that gets past the fork seal will often leak onto the brake caliper and cause a loss of braking power Fork seals should be replaced as soon as possible to prevent dirt from getting into the fork and slider Then while you re inspecting the fork seals check the front wheel and steering head for worn bearings You should know that Harley Davidson motorcycles contain tapered wheel bearings in the front wheel that require more care than the sealed ball bearings
40. ke engine moves the crankshaft one half of a complete revolution To complete one full cycle the crankshaft must make two complete revolutions or rotate 720 The intake compres sion power and exhaust strokes repeat and continue during the operation of the four stroke engine The crankshaft has a flywheel assembly which is a large round disc shaped weight It s intended to help keep the engine spinning during the three non power producing strokes of the four stroke engine Because there s only one power stroke for every two crankshaft revolutions the inertia produced by the crankshaft flywheel assembly aids in smoothing abrupt crankshaft movement during the power stroke The flywheels that are used on large displacement V twin four stroke motorcycle engines are large to keep the engine running smoothly Four Stroke Engine Components The four stroke V twin engine design allows for the greatest amount of engine displacement in the smallest overall area For a long time Harley Davidson engines were 45 air cooled four stroke V twin designs with both rods sharing the same crankshaft pin one rod was forked to allow the other rod inside it Figure 8 Now Harley Davidson also has an engine that s of the liquid cooled variety that uses a 60 V twin engine FIGURE 8 A forked connecting rod is used in this engine design Harley Davidson Maintenance FIGURE 9 Even though it s physically smaller the cast iron cyl
41. l also rotate However since a freewheeling gear must oppose a sliding or fixed gear in a constant mesh transmission the countershaft won t rotate in this transmission position First Gear When the transmission is shifted into 1st gear the shift drum slides the shift fork that s attached to the sliding 3rd gear on the counter shaft into freewheeling 1st gear Since 1st gear on the main shaft is also a sliding gear this motion attaches the countershaft to the main shaft The fixed 5th gear on the countershaft will make the main drive gear rotate delivering power to the final drive pulley Second Gear When the transmission is shifted into second gear the shift drum slides the countershaft sliding 3rd gear out of the countershaft freewheeling 1st gear and into the countershaft freewheeling 2nd gear This attaches the countershaft to the main shaft as the main shaft 2nd gear is also a sliding gear The transmission is fully engaged now at a slightly higher gear ratio than when it was in first gear Output is realized through the countershaft fixed 5th gear again delivering power to the final drive Third Gear When the transmission is shifted into third gear the shift drum must do two things at one time Second gear must be disengaged by moving the countershaft sliding 3rd gear away from countershaft freewheeling 2nd gear while the main shaft sliding 2nd gear slides into the main shaft freewheeling 3rd gear Since 3rd gear on th
42. longevity of any engine is dependent on the routine maintenance it receives The valve trains on Harley Davidson V twins require specific and careful attention in order to run long and strong First we ll discuss routine maintenance on engines like the Shovelhead and the Evolution then we ll go over some points specific to Harley Davidson chassis maintenance The first step in any tune up is to obtain the proper factory workshop manual for the motorcycle in question and follow it carefully Now is a good time to put into practice all of the concepts and methods you learned in previous chapters The Shovelhead engine uses hydraulic valve adjusters or tappets much like those found in American automobiles Although they re designed to maintain valve clearance these adjusters encounter heat and wear and therefore require periodic adjustment Remember that the engine must be cold before you can set the valves Begin the procedure for setting the valve clearance by removing the spark plugs This makes it much easier to turn the engine over while you find top dead center compression You must have the piston on top dead center compression before you set the valves Watch the rocker arms as you turn the engine over If you have the piston at top dead center and the intake valve is closed you have the engine set correctly Once you ve determined that the cylinder you re concerned with is in the correct position slide the pushrod covers out
43. mes you ll find a machine that will shift into one gear but won t shift into the next gear This problem is often caused by the shift return spring which returns the shifting lever to its original position This problem can usually be repaired by replacing the spring and in most cases won t require the complete disassembly of the transmission The spring is usually located near the clutch assembly Strange Sounds Occasionally you ll have customers who will complain of strange sounds coming from the transmission of their motorcycle Strange transmission sounds can range from a low growl to a high pitched whine Next we ll describe the most common noises that can usually be attributed to a problem with the transmission Any unusual noise which is coming from the transmission will require you to disassem ble and carefully inspect for and replace any worn or broken parts Constant growling sound A low growling sound usually indicates a bearing failure When a bearing failure occurs it may cause a transmission shaft to move slightly out of position When this occurs the gears won t mesh properly and produce a low growling noise In this case not only does the bearing need replacing but often the gears need replacing as well Clunking noises Another characteristic sound which indicates a transmission problem is an excessive clunking sound when the engine is in a particular gear while under a load Usually this indicates broken teeth on
44. n Maintenance 39 As we mentioned the largest benefit of using the chain type final drive system is the wide variety of available sprocket sizes that allow you to change the gear ratio for the final drive to match your riding conditions Chain maintenance To properly lubricate the chain first brush off any dirt and grime using a soft hand brush Then lubricate the chain using a high quality chain lubricant It s important to lubricate the chain between the side plates and rollers to allow for maximum lubrication To clean an excessively dirty chain you must remove the chain from the motorcycle To do this you must locate and remove the spring clip on the chain master link then press the master link from the side plate using a special tool which is available at most motorcycle dealership parts departments Once removed you ll need to soak and wash the chain thoroughly in a pan of solvent such as kerosene Be sure to wear eye protection when performing this procedure After you ve thoroughly cleaned the chain you can remove it from the solvent and dry it using compressed air or wipe it clean and dry with a clean shop rag If using compressed air to dry the chain eye protection is a must After the chain is clean and dry you ll need to apply chain lubricant wipe all excess lubricant from the chain surface and then reinstall the chain onto the motorcycle Chain installation To install the chain place the transmission in neutral a
45. ncreases If the clutch is adjusted while the engine is hot clearance at the push rod bearing will be insufficient and clutch slippage will occur The clutch cable adjuster is located midway between the clutch cable ends As with the previous study units the procedures in this study unit are general in nature and not intended to be used for actual disassembly and repair Their purpose is to familiarize you with the types of activities you ll encounter Always refer to the appropriate motorcycle or ATV service guide for maintenance information The service guide contains all the information to do the job correctly including detailed instructions for the specific make and model of motorcycle or ATV special tools and service tips Above all the service guide contains the appropriate safety information The following example steps will help you to understand how to adjust the clutch 36 Loosen the lock nut and turn the adjuster in all the way to provide maximum play in the cable at the clutch lever Loosen the clutch adjuster screw lock nut which is located under the clutch access plug and turn the push rod adjusting screw inward clockwise to take up any of the play in the push rods Back out the adjusting screw to 1 full turn and tighten the lock nut while holding the adjusting screw with an Allen wrench a Harley Davidson Maintenance Scn Addidit a v Harley Davidson Maintenance of 4 Pul the clutch leve
46. nd connect one end of the chain onto the front sprocket Feed the chain through the sprocket until the chain is on both the wheel and transmission sprockets Connect the ends of the chain with a new master link making sure that the spring clip open end trails the direction of chain travel Figure 24 The clip must be installed correctly to prevent the chain from coming apart FIGURE 24 Be sure to install the master link in the proper direction or the clip can come off causing the chain to come apart image courtesy of Yamaha Motor Corporation U S A GY ed Ve mee ZY hi D JOINT CLIP DIRECTION OF TURNING Chain adjustment The chain must be adjusted on a regular basis as the chain wears When checking the chain adjustment you should place the motorcycle upright with the transmission in neutral and with the rider on the machine Figure 25 A properly adjusted chain should have the specified slack up and down movement midway 40 FIGURE 25 In this picture the customer is sitting on the motorcycle while the technician checks for the proper chain slack Harley Davidson Maintenance between the transmission sprocket and the rear wheel sprocket The manufacturer will supply the specification in the service and owner s manual You ll notice that different models require different amounts of chain slack To adjust the chain first loosen the axle nut then turn the chain adjusting nuts clockwise to tight
47. of the way to expose the adjusters Loosen the adjuster lock nut on the pushrod and turn the adjuster up until there s some up and down play in the pushrod At this time turn the adjuster down until you ve removed all of the play Look for the split in the lock nut you can use it as a reference mark You may have to turn the lock nut in order to see the split Turn the adjuster down four full turns This is the specification listed in the factory workshop manual You may choose to add another half turn which takes all of the play out of a well used adjuster and lock nut assembly At this point tighten down the lock nut and repeat the procedure for the other valve s pushrod You need to be careful here because the hydraulic tappet is full of oil and holding the valve off its seat It will take several minutes for the valve spring to compress the oil out of the hydraulic tappet After you ve waited five minutes repeat the process for the other cylinder remem bering to find top dead center compression for that cylinder as well As long as you re inspecting the top end it s a good idea to check the side to side clearance of the rocker arms This clearance will manifest itself as a tapping or ticking noise that sounds very much like a loose valve With the piston on top dead center compression try to slide Harley Davidson Maintenance Spark Plugs Carburetor 43 the intake rocker arm back and forth It should only have
48. oft tipped hammer In most cases to get the proper belt tension required by the manufacturer a belt tension tool is required This special tool is available from your local dealer After verifying the belt tension tighten the rear axle nut to the specified torque given by the manufacturer On some models you aren t required to loosen the axle nut to adjust the belt tension The service or owner s manual will specify this when necessary Road Test 3 The clutch found on V twin motorcycles is part of the drive system On motorcycles that use a primary drive with a chain what type of clutch design is used The clutch outer shell contains pieces that are together The V twin motorcycle has a primary drive system that uses a chain or to transmit power from the crankshaft to the transmission Primary chain tension is adjusted by a shoe located in the True or False The clutch outer shell may also include the charging system rotor as part of the component Which chain used in a primary drive system is the most common The friction plate material used in a clutch is made of a or material True or False Adjustments to a clutch should be made while the engine is at its normal operating temperature True or False When the clutch is engaged the power of the crankshaft to the rear wheel is separated Check your answers with those on page 47 42 Harley Davidson Maintenance V TWIN MAINTENANCE The reliability and
49. one or more gears This condition requires a complete disassembly as well as a complete inspection of all of the transmission components as broken teeth will normally damage other parts within the transmission 30 Harley Davidson Maintenance Jumping Out of Gear A transmission that jumps out of gear usually indicates that there are worn dogs or slots on the transmission gears When dogs and slots become excessively rounded the gears tend to slip out of the holes when engine rpm increases causing the engine to jump out of gear In this situation the gears as well as the shift forks need replacing The shift forks need to be replaced because they become damaged from the excessive pressure caused from the gear jumping out of gear Road Test 2 The transmission provides gear shifting to allow increases in speed without overworking the True or False The 4 speed direct drive transmission is identical in design to the 5 speed direct drive transmission except for the extra gear in the 5 speed system The speed direct drive transmission uses a shift drum to move the shift forks The speed direct drive transmission uses a cam plate to move the shift forks Define a constant mesh transmission The letter S stands for which type of transmission gear A low growling sound in a transmission will usually indicate a failure If you are working on a motorcycle that has a symptom of difficult shifting what should yo
50. plined to the shaft they rotate at shaft speed The purpose of this type of gear is to engage and disengage transmission gears A shift fork moves a sliding gear left or right across the axis of the shaft A sliding gear has dogs on its sides which are designed to engage freewheeling gears Sliding gears will normally be abbreviated as S Freewheeling Gears Freewheeling gears rotate freely on the shaft to which they re attached Freewheeling gears are usually held in place by retaining rings A freewheeling gear doesn t have to rotate at shaft speed and has slots or protrusions also known as dogs on its side to allow for engagement with a sliding gear For a constant mesh transmission to operate correctly there must be a freewheeling gear meshing with a sliding gear or fixed gear on the opposite shaft Freewheeling gears will normally be abbreviated as FW Main Drive Gears Main drive gears are designed to ride on bearings and are mounted on the main shaft There are two different types of main drive gears one is used on the 5 speed transmission while the other is found on the 4 speed transmission 5 speed main drive gear The final drive sprocket or pulley is connected to the 5 speed main drive gear When the transmission is in any gear other than fifth or top gear this main drive gear is driven by a gear on the countershaft While in top gear it s locked to the main shaft by a sliding gear which is also attac
51. r in all the way you may have to do this multiple times to set the ball and ramp release mechanism 5 Adjust the cable adjuster to provide inch play at the clutch lever then tighten the cable lock nut and return the adjuster boot over the adjuster Common Cluich Problems There are two common clutch problems found with the V twin multiplate manual clutch The first is a clutch that slips Clutch slippage occurs when the clutch doesn t have the ability to transfer all of the engine s power flow The clutch will slip if the rider releases the clutch lever and the motorcycle engine revs up without any power going to the rear wheel This problem may be caused by improper clutch adjustment a weak clutch spring or worn clutch plates The second common problem that may be found with a clutch is known as clutch drag Clutch drag occurs when the clutch is unable to fully disengage Clutch drag will be evident when the engine power can t be disengaged from the rear wheel An example of this condition is when the clutch lever is squeezed in and the motorcycle is still trying to move forward This condition may be caused by warped or binding clutch plates a worn clutch outer shell or clutch hub improper clutch adjustment or a worn release mechanism Manual Clutch Operation We ll now review the operation of a multiplate manual clutch as it s used on the V twin motorcycle It may also be helpful to review the mat
52. s even include the charging system rotor on the clutch outer shell These clutches contain multiple coil springs or a diaphragm type spring that applies pressure against the friction and steel plates to ensure a positive clutch engagement Clutch Lubrication The primary chain case lubricant which again is used to lubricate the clutch should be changed in accordance with the manufacturer s recommendations You can drain the lubricant into a suitable container by removing the drain plug at the bottom of the primary chain case After draining the oil and installing the drain plug you can refill the chain case through the clutch cover opening with the recommended amount of oil When you have the correct amount of lubricant in the case the lubricant is level with the bottom of the outer diameter of the diaphragm spring or the lubricant overflows out of the oil level screw hole depending on the model Refilling the oil should be done when the motorcycle is standing in an upright and level position Clutch Adjustment To obtain the maximum life from the clutch on a V twin motorcycle it s very important to perform the correct clutch adjustment procedure at every service interval Also if any clutch components are replaced during normal servicing the clutch must be adjusted Clutch adjustment should be performed with the motorcycle at room temperature since the clearance at the adjuster screw will increase as the power train temperature i
53. spects of the V twin motorcycle including engine design drive systems and maintenance procedures Before we get too involved discussing the current model design we ll give you a brief history of a legendary American motorcycle manufacturer the Harley Davidson Motor Company HISTORY OF THE HARLEY DAVIDSON MOTOR COMPANY The Harley Davidson Motor Company was founded in 1903 by William S Harley and Davidson family members William Walter and Arthur These four men started their company in a small tool shed in Milwaukee Wisconsin Today their story has become a legend among motorcycle enthusiasts The Early Years 1903 1929 The first Harley Davidson motorcycle was a belt driven bicycle based model with a 3 hp single cylinder engine This motorcycle lacked suspension and had an engine that was based on a French design There was no clutch or transmission it was a true direct drive and lubrication of the moving engine parts was provided solely by gravity In 1906 the company increased the horsepower of this motorcycle from 3 to 4 by increasing the cylinder bore The first Harley Davidson V twin was offered publicly in 1907 in response to the multicylinder models offered from the companies Thor Indian and other marquees that are no longer in business The first versions of this motorcycle used what were known as suction valves which used the suction created by the movement of the piston Because this design was impractical l
54. the pressure in the combustion chamber to increase dramatically This phase is known as active combustion Post Combustion The third phase of combustion occurs as the piston begins moving downward At this time most of the charge has been consumed so the remaining burning doesn t contribute much towards producing more power As the piston continues its downward movement the volume inside the combustion chamber increases This increase in volume allows the pressure to drop and the remaining power to be absorbed by the piston The combustion chamber and cylinder eliminate the spent gases and start the next cycle of fresh air and fuel mixture burning This phase is known as the post combustion phase 8 Harley Davidson Maintenance Other Combustion Factors Next we ll discuss the factors that influence the combustion process and engine performance The compression ratio of a four stroke engine is a major factor in engine performance For example if you increase the compression ratio you can in many cases increase the power output of the engine The compression ratio is the difference in the volume of air when the piston is at bottom dead center BDC compared to the volume of air trapped when the piston is at top dead center TDC Volumetric efficiency is the measurement of how much air is actually being taken in by the engine compared to how much it can hold according to the size of the cylinder A four stroke V twin engine motor with a
55. u adjust first to try to correct the problem Check your answers with those on page 47 Harley Davidson Maintenance 31 V TWIN MOTORCYCLE DRIVE SYSTEMS As with any motorcycle the V twin motorcycle uses three systems to transmit the power made at the engine to the rear wheel These systems are the primary drive system the clutch system and the final drive system Primary Drives All motorcycle engines require a gear reduction system that s used to transfer the power from the crankshaft to the transmission and then from the transmission to the rear wheel The gear reduction system used for transferring the power from the crankshaft to the clutch is called the primary drive As you already know gear reduction is necessary to allow the engine to remain in the appropriate rpm range while maintaining various speeds at the rear wheel In other words we need gear reduction systems so that the engine can revolve at one speed while the rear wheel turns at another speed A clutch is needed to engage and disengage the power from the crankshaft to the transmission Before we discuss and learn about the type of clutch used in V twin motorcycles we ll first discuss the types of primary drive systems found in this type of motorcycle engine There are two basic methods of connecting the engine to the clutch and transmission A V twin motorcycle primary drive system transfers power from the crankshaft to the clutch by using a chain or a belt
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