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2F-440-3 Service Manual

1. 6 Qty Description Req d Recoil Starter Assembly 338 4 1 811 00 complete includes items 1 thru 19 65 rope Recoil Starter Housing Rope Drum Recoil Spring Intermediate Plate Cover Plate Starter Pawl Spring Cap Pressure Spring Inner Spring Cap Screw Lock Washer Rope Bushing landie complete includes 338 4 1 017 00 197 41 070 00 252 41 429 21 338 4 1 006 00 338 4 1 005 00 252 41 065 10 252 4 1 066 00 252 41 067 00 102 41 499 00 000 4 1 50 098 000 40 67 005 102 41 469 00 102 41 801 00 QOOADAANNA a QONNNN ls 252 41 007 00 252 41 009 00 252 41 015 00 252 41 016 00 000 40 39 145 252 4 1 807 00 338 4 1 007 00 338 4 1 810 00 079 11 017 00 000 4 1 50 136 000 40 64 506 000 4 1 01 069 338 41 016 00 Retaining Ring Retaining Key Tensional Pin Rope 65 Gasket Carrier Dust Seal Socket Cap Screw Lock Washer Hexagon Screw Recoil Starter Clamp BRON PB owe aa Ps de a at Rockwell JLO Engines WARRANTY Rockwell Jio as manufacturer warrants each engine for a period of 90 days from date of original retail purchase or from November 15 1971 whichever is later Under this warranty Rockwell Jlo will replace for the original purchaser any part or parts found upon examination by an authorized service outlet or by central warehouse distributor to be defective in material and or workmanship All tr
2. oe Nut 000 4 1 97 006 46 Terminal Case 002 44 556 00 Connection 002 44 550 00 F 1 28 Ignition Cable Bracket 002 50 120 08 A 39 000 4 1 50 438 000 40 42 208 002 44 47 2 90 Socket Cap Screw Lock Washer Grommet 43 N2 2 0 NNNN 41 a 18 42 _ Magnetic Flywheel Armature Plate Cam Centrifugal Weight Ignition Points 2 Condenser Generator Coil Generator Coil Lighting Coil Lubricating Wick Washer Lock Washer Screw Spiral Spring Ring Segment Lock Washer Socket Cap Screw Washer Lock Washer Grommet Spiral Band Ignition Coil Socket Cap Screw Spring Washer Protective Cap Protective Cap Ground Cable 4 6 Connector Cable Connector Socket Cap Screw Magnetic Flywheel Flange Ignition Cable 14 Ignition Cable 20 Spark Plug Connector Spring Contact Nut Cover Plate 000 43 05 198 000 43 05 331 000 43 05 728 000 43 06 019 000 43 06 223 000 43 06 530 000 43 05 537 000 43 05 538 000 43 05 534 000 43 06 313 000 43 12 531 000 40 76 008 000 4 1 50 094 000 43 08 768 000 43 12 538 000 40 64 504 000 41 50 115 000 40 51 006 000 40 64 505 002 44 450 01 002 44 127 16 000 43 05 606 000 4 1 50 434 000 40 42 208 002 44 498 00 002 44 499 00 002 44 140 11 002 44 523 00 000 43 10 004 000 41 50 120 338 11 002 11 002 44 152 36 002 44 152 52 002 44 275 80 002 44 27 6 0 4 002 44 27 7 90 338 1 1 008 10 NNN ANANA AANA O
3. the spark plug area to accept the timing device B Turn the flywheel clockwise towards TDC top dead center until breaker points are visible Use a clean feeler gauge and adjust the gap Note if flywheel is removed use an old cam and rotate until the points are at their largest opening Check gap and adjust to specifications as neces sary Repeat procedure for the other set of points C Advance the centrifugal weight Hold in place using locking pin a tool specially designed for this purpose D Attach one lead of the ignition continuity light to terminal of No 1 cylinder coil the other to ground engine casting For the second cylinder attach continuity light lead to No 2 cylinder coil terminal solid blue wire is for No 1 cylinder blue yellow wire is for No 2 cylinder E Bring piston to TDC and adjust dial to zero F Working with No 1 cylinder turn flywheel counterclock wise away from TDC closely observing dial indicator and x timing light When piston reaches the timing point the light will dim indicating the opening of the points Now check the dial indicator If timing does not agree with specifica tions do not change the breaker point gap adjust by loosen ing and rotating the stator plate assembly Illus F Rotate assembly clockwise to retard counterclockwise to advance the ignition Correct breaker point gap will insure maximum ignition output Important to time cylinder No 2 repea
4. Donaldson Expansion Chamber Racing back into the cylinder using sound waves and sound energy This is accomplished at the speed of sound which allows the engine to produce higher torque at high RPM s How Tuning Works The megaphone effect of the expanded intake tube scavenges exhaust gas from the cylinder allowing rapid replacement of the fuel air mixture from the crankcase Reflected sound waves and sound energy stop over scavenging and return fuel air mixture to the cylinder It gives a super charging effect even though it operates from the exhaust rather than the intake side Over scavenging is also retarded by moderate muffler back pressure Silencing is accomplished after power is maximized by acoustical packing in the resonator outlet tube plus cham bering and baffling which gives an effective 2 pass muffler design Racing Expansion Chambers Expansion chamber incorporates power tuning to increase horsepower of two cycle engines up to 25 per cent Tuning Courtesy of Donaldson Muffler Co E JLO Twin Cylinder Engines Disassembly and Assembly Procedure Model LR 440 2 2F 440 3 Disassembly A Recoil Starter Remove four screws holding recoil to fan housing and the spacers and washers Remove recoil assembly complete For detailed service instructions refer to Recoil Starter Disassembly and Assembly B Lower Fan Pulley and Carrier Assembly Remove three hexhead screws on carrier Remov
5. NNO a anal cons Starter complete includes 2 thru 9 Field Winding Armature Bushing gt Bushing Bushing Drive Gear Brushes set of 4 Pressure Spring Bracket Socket Cap Screw Lock Washer Hexagon Screw Nut Bracket Hexagon Screw Nut Spring Washer Starter Gear Pressure Flange Clamping Ring set of 2 Oil Seal Hexagon Screw Lock Washer Rectifier Relay 002 44 037 00 000 43 08 313 000 43 05 533 000 43 07 812 000 43 07 801 000 43 07 806 000 43 07 421 000 43 08 745 000 43 08 773 338 1 1 011 00 000 41 000 40 64 5 000 4 1 01 093 000 41 97 010 338 11 021 00 000 4 1 01 067 000 4 1 97 007 000 40 42 207 338 1 1 010 00 338 11 015 10 002 42 640 30 000 42 31 891 000 41 74 011 000 40 64 508 000 43 08 352 000 43 15 008 A2 NAa dl P NNM NNANM NM 1P Fan Case Shek ek ok A ok ok OANOAMARON DQOANDUAWN Fan Case Impeller Shaft Nilos Ring Bali Bearing Spacer Locking Ring Clamp Washer Pulley Half Small Spacer Lock Washer Nut Socket Cap Screw Lock Washer Pulley Half Large V Belt Oit Seal O Ring 338 14 017 00 399 14 004 00 338 14 007 02 000 40 47 735 000 39 07 113 338 14 008 00 000 40 6 1 432 338 14 009 00 399 14 002 00 338 14 012 00 000 40 64 510 000 41 95 202 000 4 1 74 128 000 40 64 607 399 14 001 00 000 42 17 508 000 42 31 548 002 52 665 00 Qty Req d 4 4 4 2 2 1 2 2 2 4 4 1 4 4 2 1 1 1 Recoil Starter 10 11
6. SVM 7735 scorpion Service Manual For JLO Axial Fan Twin Cylinder Engine Model LR 440 2 2F 440 3 e 2 CYCLE ENGINE FUNDAMENTALS ENGINE BREAK IN EXHAUST SYSTEMS e DISASSEMBLY AND ASSEMBLY INSTRUCTIONS OF BASIC ENGINE INCLUDING RECOIL STARTER e ELECTRIC STARTER MOUNTING INSTRUCTIONS e IGNITION TIMING PROCEDURE e SPARE PARTS LIST SERVICE TOOLS d 2 Cycle Engine Fundamentals The 2 cycle air cooled gasoline engine has become very popular today for snowmobiles ATV s and other recreational vehicles It is uniquely qualified for these applications be cause of its relatively high power output light weight and ease of lubrication with fewer moving parts than conven tional 4 cycle engines However in order to get the best possible use and assure that it retains its high degree of dependability and endur ance it must receive proper care and maintenance Since the life expectancy of any 2 cycle gasoline engine depends to a great degree on the level of maintenance it receives it is necessary for us to know something about the basic fundamentals of an engine and how it functions in order to determine and apply the correct amount of maintenance Operation The JLO 2 cycle engine is of the loop scavenged 3rd port design type the most widely used design today It uses a mixture of gasoline and oil for combustion lubrication and cooling It fires on every stroke of each piston There are two power s
7. ansportation charges on parts submitted for warranty shall be borne by purchaser This warranty shall not apply to Rockwell Jlo products which must be replaced or repaired due to normal wear misuse negligence or accident or which have been repaired or altered outside Rockwell Jlo s authorized service outlets There is no other warranty expressed or implied and Rockwell Jlo shall be under no liability whatsoever in respect of any loss damage injury or expense arising from any defect in said product or products scorpion inc CROSBY MINNESOTA 56441 SVM 7735 6 71 7 5M lt Printed in U S A
8. ate and gasket ring Note when installing cover plate the spring cups have a tendency to become misaligned To retain them use a pair of clips 7 Check the complete assembly for free play if Mounting Instructions for Electric Starter Kit Model LR 440 2 2F 440 3 Twin Cylinder Engine Installation 1 Install front mounting bracket on crankcase using the two socket cap screws provided PAI 2 Insert starter unit into front bracket and loosely fasten with 2 hexhead screws 3 Loosely install the rear support bracket to the starter Now fasten support bracket to the engine and then go back and firmly tighten it to the starter Note to simplify installa tion of rear bracket the engine mounting holes may be slotted Removal 1 To remove reverse the above procedure Ring Gear Kit A Pry out oil seal with screwdriver B Insert new larger seal flush with the crankease C Lightly grease ring gear hub D Install the two ring gear wedge rings as follows first insert the smaller of the two rings into the ring gear opening with the tapered end facing you then the larger ring with the tapered end facing the engine E Insert pressure flange and tighten 11 Timing Procedure Model LR 440 2 2F 440 3 Twin Cylinder Engine With the recoil starter and carrier assembly removed proceed as follows A Attach the dial indicator to the cylinder Make a small notch in the cylinder head cover around
9. ation for piston No 2 K Crankcase To separate crankcase halves hold upper shell with left hand and rock slightly back and forth to break the sealing surfaces If necessary strike side of crankcase with rubber hammer to complete the separation Remove crankshaft L Crankshaft Crankshaft bearings With crankshaft on work surface remove oil seal and align ment washer from P T O end To remove bearings use special puller Slide puller body over crankshaft and align bolt with crankshaft end Slip puller half shells around the bearing and engage them on puller grooves Slide retaining ring over half shells to keep them on the bearing Using two 27 mm wrenches turn puller center bolt with one wrench while holding puller body with the other Keep turning puller center bolt clockwise until it pulls the bearing to the end of the crankshaft i JLO Twin Cylinder Engines Disassembly and Assembly Procedure Model LR 440 2 2F 440 3 Assembly 1 Crankshaft Heat crankshaft bearings in oil preheated to 180 F After reaching temperature quickly slip bearing over end of crankshaft it should fall freely on the counterweight Using a hollow pipe with a diameter approx imately that of the inner bearing race hit pipe with a rubber hammer and seat the bearing on the shaft The bearing should now rest se curely and turn freely Repeat pro 4 cedure for bearing on other end of crankshaft 2 Crankcase Inspect both halves of
10. crankcase and clean carefully removing any left over adhesive or burrs Apply Permatex type sealing compound to lower crankcase shell sealing surfaces and a little on the bearing surfaces Note that no seal gaskets are used Place crankshaft in lower shell and align spacers with machined grooves Place oil seal on P T O end of shaft flush with the casting Turn crankshaft with your hand to check freedom of movement and make sure that the oil seal is seated Install upper crankcase shell and seat by tapping it lightly 3 Piston and Cylinder Clean carbon deposits from the piston Check to see that rings move freely in their grooves Mate piston with cor responding cylinder The piston must be installed with the arrow pointing toward the exhaust port Insert needle bear ings into the connecting rod then place a daub of grease on the connecting rod so that the spacers installed later will adhere to it Gently guide the piston over the connecting rod and insert the wrist pin Snap circlips into each side of the piston using a screwdriver or needle nose pliers Install cylinder base gasket Place a V shaped wood block under the piston resting it on the crankcase After lining up the rings with the locating pins on the piston compress them with a ring compressor Rest the piston on the wood block and carefully slide the cylinder over the piston until the rings disappear into the cylinder Be sure you use a gasket of the same color as was removed f
11. d toward the inlet side of the engine Rotate engine once and then remove solder Measure the thickness It should be between 040 and 060 If it is not achieve this by changing heads and or head gaskets Assemble cylinder heads with corresponding cylinders and install washers and nuts Tighten to specifications 10 Spark Plugs Install and tighten spark plugs Complete tightening of flywheel nut 11 Lower Axial Fan Belt Pulley Assembly Install the first pulley half with dished side facing the housing the fan belt the second pulley half with the dished side fac ing out and the carrier assembly Tighten carrier screws while slowly rotating the crankshaft with your hand to pre vent squeezing the fan belt 12 Recoil Starter Install recoil starter assembly using the four hexhead screws clamps and lockwashers For service details refer to Recoil Starter Service Instructions JLO Twin Cylinder Engines Disassembly and Assembly Procedure Recoil Starter Model LR 440 2 2F 440 3 Disassembly A Take off cover plate and gasket ring by removing three slotted or Philipps head screws B Lift out pawl assembly including spring caps and pressure springs C Remove intermediate plate D Remove handle assembly To provide needed slack for removal of handle pull rope part way out and tie a knot E After removing handle untie knot in rope and carefully release spring tension by holding recoil pulley with one hand and l
12. e dust seal carrier lower pulley halves and V belt C Upper Fan Belt Pulley Assembly To keep impeller from turning insert a punch through the fan housing and into the impeller body With a 17 mm wrench remove fan nut Pull out the loosened assembly nut washer spacers and upper pulley halves D Flywheel Magneto Make sure spark plugs are tight Working against engine compression with a 27 mm wrench remove crankshaft nut by striking wrench a few sharp blows with a hammer To pull flywheel attach special puller to flywheel flange using three of the recoil starter screws previously removed Screw into the three holes on flange and tighten Turn puller until bolt touches tip of crankshaft With a 24 mm socket wrench turn puller bolt clockwise and extract flywheel Note that key may come loose and adhere to the flywheel magnets E Intake Manifold Remove the four nuts holding manifold and upper coil cover plus the two lower coil cover screws Remove screw holding spark plug wire to side of fan housing F Fan Housing Armature Plate With a special Allen Head wrench remove the 4 socket cap screws holding fan housing to crankcase To loosen place unit with fan housing protruding over end of workbench and holding housing with one hand hit light but sharp blows around periphery Pull housing straight out past the crank shaft careful not to cut the oil seal on the sharp edges of keyway of the shaft Disconnect solid blue a
13. ent Spark Plug The spark plug provides the electric spark necessary for ignition of the compressed fuel air mixture in the cylinder There are many types and sizes of spark plugs depending on engine design and operating characteristics Most single cylinder 2 cycle engines use the short reach type spark plug while the newer angled head single and twin cylinder engines use the long reach type spark plug The most com monly used thread sizes are 10 mm 14 mm and 18 mm Spark plugs tip temperatures are also extremely important in proper engine operation therefore they should be selected according to engine design and type of service Terminal nut Insulator Terminal bolt Crimping ring Gasket seal Center electrode Screw thread Ground electrode Courtesy of Robert Bosch GMBH Mounting bell Rotating cam Oxide magnet with pole shoe Starting Stopping Fuel Mixture Starting Procedure 1 Turn switch to on position 2 Close choke warm engine requires little or no choking 3 Open throttle slightly when cranking the engine 4 As soon as the engine starts open choke and release throttle 5 Electric start Turn switch to start position Release as soon as the engine starts switch will remain in on position Do not continue cranking the engine if it fails to start after approximately 30 seconds Allow the starter to cool before making another attempt If the batte
14. er Engine Bore 2 658 Stroke 2 362 Displacement 428cc Compression Ratio 7 5 to 1 Actual Maximam TOrque 28 4Ft Lbs BHP at 6000 RPM Brake PYRPM 37 5 H P at 6250 RPM Lighting Cof 12 Volt 75 Watt Contac Breaker Gap 014 to 016 Ignition S8fting Before TDC Cam Fully Advanced 083 to 102 Spark PIIgS Thread 14 x 1 25 mm Long Reach Type Gap 016 to 020 Type BOSCH Medium Load W 240 T 2 Full Load W 260 T 2 3 Racing W 310 T 17 ES PR m Rotation Counterclockwise viewed from P T O End Fuel Offirxture 20 1 1 Qt Oil to 5 Gals Gasoline Lubrication Mixture of Good Brand of Gasoline 90 octane minimum and Special Two Cycle Engine Oil Carburet6r Type WDorHD J Starter Rewind Type Standard Electric Optional Recoil Rope Steel 3 Weight nag 62 Ibs 2 13 14 Wiring Diagrams Bosch Model LR 440 2 2F 440 3 Twin Cylinder Engine STARTER JLO MOTOR PE ENGINE 12 VOLT BATTERY O Terminal 85 needed for rubber mounted salenoid only Packard connector 3 380 80 and blades 296 54 81 Packard connector 297 34 22 and blades 296 55 10 Load not to exceed 0 Use 12 valt battery cable All others 14 G 60 wotts at 12 volts Battery Magneto Rectifier High tension coil Packard connector Starter r Solenoid Packard Key switch Lights l Spark plugs A ee ogee blue yellow black Dimensional Drawing and Special Service Too
15. etting the rope feed back slowly to gradually release spring tension F Remove nylon rope bushing G Lift out rope pulley with pliers Keep coil spring in position using a screwdriver H Turn recoil housing upside down in your hand and smack down sharply against workbench This will release spring tension within the housing enabling you to grasp the spring and gradually and safely uncoil it Assembly 1 Clamp the special assembly jig in a vise Insert recoil housing in jig and lower the hub locking it in position with a cotter pin Hook end of spring onto the small boss cast in the housing and start rotating the housing clock wise slowly guiding the spring into position Complete the recoiling and remove housing from the jig 2 With rope pulley in one hand and a Philipp s screwdriver in tne other guide the screwdriver into the spring loop and engage the end of the spring on the pulley hub The spring loop must be properly seated on the pulley hub 3 Before installing rope turn rope pulley counterclockwise as far as possible Back off 1 2 to 3 4 of a turn and jam punch or screwdriver between pulley and housing to main tain tension Align rope hole with outlet of starter housing and insert the rope Install nylon bushing and handle assembly Remove screwdriver and release tension while guiding the rope into the starter housing 4 Install the Intermediate Plate 5 Install Starter Pawl Assembly 6 Install cover pl
16. k Plate Spacer 338 03 006 10 Key 000 40 89 615 Nut 000 4 1 95 507 Lock Washer 000 40 64 520 Ball Bearing 000 39 07 521 When ordering spare parts 1 Indicate engine model number and serial number 2 Order parts by part number not by illustration number 3 Give exact description of part required 4 Indicate quantity required k pe and quantity as required rocedure Piston and Cylinder Piston including items 2 thru 5 A Piston Ring Piston Ring Wrist Pin Circlip Cylinder includes illustration 7 studs Stud Cylinder Head Cylinder Head Cylinder Head Gasket Washer Nut Stud Cylinder Base Gasket Yellow 5 mm Red 3 mm Yellow brown 75 mm Grey 1mm Intake Gasket Intake Manifold HD Nut Spring Washer Nut HD only Lock Washer HD only 000 42 12 488 000 42 14 488 338 05 002 00 000 40 62 142 438 07 814 10 000 4 1 24 085 438 07 006 00 438 07 007 00 438 07 002 00 000 40 51 010 000 41 97 011 000 4 1 24 360 338 07 008 00 338 07 025 00 338 07 026 00 338 07 027 00 338 07 01 1 00 338 07 017 00 000 4 1 97 010 000 40 42 209 000 4 1 96 01 1 000 40 64 508 See items 3 and 9 Engine Assembly NM hONND 0 00 0mNN mo NNARA Z N xx e Spare Parts List Model LR 440 2 2F 440 3 Electrical a Bosch Electrical Equipment Bosch 34 35 T oe oY a 000 4 1 50 097 000 40 5 1 005 000 40 64 504 Socket Cap Screw Washer Lock Washer
17. ls Model LR 440 2 2F 440 3 Twin Cylinder Engine J eu WA E Connector Body 3138080 a PACKARD CONNECTOR TERMINALS O GROUND WIRE O O LIGHT WIRE j SHORT CIRCUIT WIRE Bearing Puller Half Shells 2 Retaining Ring Flywheel Puller Guide Pin 5 Assembly Jig starter R P M Indicator Universal Mounting Plate Spark Plug Wrench 14 mm single end Bar use with sockets Wrench double 13 x 17 mm open end offset to clear carburetor Gasket Set with Seals 444 31 807 00 444 31 072 00 444 31 071 00 444 31 843 10 444 3 1 666 00 444 31 863 10 000 15 30 010 444 31 804 10 000 15 20 421 000 15 21 012 444 31 682 00 438 6 1 802 00 15 16 Spare Parts List Model LR 440 2 2F 440 3 Twin Cylinder Engine General View Qty Description Req d 1 Crankcase complete U N C 338 01 810 20 base thread Use with standard or electric starter 000 40 42 209 000 42 3 1 891 002 44 430 00 Spring Washer Oil Seal Electric Start Grommet E 2 Impulse Connector 002 45 513 26 3 Screw Plug 000 41 48 053 4 Gasket Ring 000 35 00 070 5 Hexagon Screw 000 4 1 01 089 6 Washer 338 03 007 00 7 Nut 000 41 97 010 8 9 0 Crankshaft KT H ly Crankshaft complete 338 86 904 00 P T O with 1 2 20 U N F female thread including items 2 thru 6 Needle Bearing 000 39 1 1 253 Chec
18. nd blue yeliow coil wires and remove entire assembly The armature plate is attached to the fan housing by two slotted screws and can be removed at this time Scratch mark its original position before removal as this will facilitate engine timing Impeller assembly should come loose and may be removed at same time as fan housing assembly The fan housing bearings can be removed at this time if necessary by punching out from the side opposite that from which they are normally inserted G Spark Plugs Remove with special socket wrench H Cylinder Heads Remove the 17 mm head nuts and lift head and gasket from cylinder block Mark cylinder head and corresponding cylinder in order to assure proper reassembly Cylinder closest to the P T O end is always considered No 1 cylinder Repeat operation for second cylinder I Cylinders Lay unit on end and with a 13 mm socket remove the 8 cylinder base nuts Unless complete disassembly is re quired remove one cylinder at a time so as to maintain crankcase alignment Set unit upright again and lightly tap cylinder with a rubber hammer and lift gently until piston clears the skirt Repeat operation for second cylinder J Piston and Wrist Pin Prior to removing mark each piston in relation to the cylinder with which it mates With needle nose pliers or special screwdriver remove the two different circlips on each side of wrist pin Gently drive out wrist pin Repeat oper
19. o vehicle tank by first mixing 1 gallon of gasoline with all the oil shaking vigorously and then adding the rest of the gaso line Always use fresh clean gasoline to avoid gumming up or clogging the carburetor Volume Equivalents 1 U S Quart 946 Liters 1 U S Quart 833 Imperial Quart 32 Ounces 1 U S Quart 1 U S Quart 2 U S Pints Exhaust Systems Tuned Mufflers Expansion Chambers Selection Selection of an exhaust system including exhaust manifold intermediate pipes elbows and muffler is a result of thorough test procedures involving measurement of fuel consumption horsepower and noise level Contrary to pop ular belief the exhaust system is not only for quieting the engine but also serves to increase the horsepower output by as much as 25 Changes made to the original equip ment exhaust system by changing any component in the system can result in loss of power and or severe engine damage For these reasons intermediate lengths of pipe between the cylinder and the muffler are particularly critical Tuned Mufflers Tuned mufflers allow the engine to exhaust its spent charge into an adequate volume and properly matched muffling system More important the mufflers are tuned incor porate designs that suck the exhaust gas from the cylinder allowing fuel and air to rapidly replace it and also cram over scavenged fuel and air mixture from the exhaust pipe Typical Exhaust Systems
20. other hand leads to incomplete combustion carbon fouling of plugs and piston overload TRANSFER EXHAUST Carburetion In order to atomize the oil fuel mixture and mix it with proper proportions of air flowing to the intake port or intake mani fold itis necessary to utilize a carburetor Carburetor design is based on the venturi principle whereby a gas or liquid flow ing through a restricted or necked down passage increases in velocity and decreases in pressure as compared to the velocity and pressure in the full size section of the passage There are various types of carburetors classified by method of delivery of fuel to the carburetor float suc tion lift and diaphragm type JLO Engines mainly use diaphragm type carburetors therefore future refer ences herein will be limited to this type of carburetor Courtesy of Walbro Carburetor Corp Courtesy of Tillotson Mfg Co Ignition The ignition system provides the high voltage electrical energy which flows across the spark plug electrode gap to create ignition spark Most small engines are equipped with magneto type ignition The magneto ignition system gener ates and transforms electrical energy into high voltage de livering it at the proper time for ignition spark Flywheel Magneto Armature plate Generator armature far ignition Cronkshaft Load generotor armature Courtesy of Robert Bosch GMBH Flyweight for ignition timing adjustm
21. rom the engine because there are four gaskets available having different thicknesses Note that the top of the piston must be within 40 008 of the top of the cylinder Use a gasket which will achieve this result Mark the dimension on the cylinder in pencil Remove ring compressor and wood block Repeat procedure for second cylinder Turn the unit over on its side and install the cylinder base nuts and tighten lightly Assemble the intake manifold and tighten the four screws Draw nuts tightly in order to evenly align both cylinders Turn unit completely over upside down and torquedown the cylinder base nuts to specifications in a crosswise pattern Remove the inlet manifold assembly previously installed only to align the cylinders 4 Impeller Fan Housing Bearings Install fan housing spacer and circlips one circlip on each side Pack fan housing opening with bearing grease and insert bearings one on each side with sealed surfaces facing outward Slide shaft thru impeller and install Nilos ring on the side of the impeller which faces the housing and then thru the bearings 5 Fan Housing Armature Plate Install the armature plate aligning it with the scratch marks previously put on during disassembly Tighten slotted screws Check the wiring protruding from the fan housing to make sure that there are no broken wires Slip the rubber grommet protecting the wires into the housing Check the O ring on the back side of the fan hou
22. ry is low use the recoil starter Operation Before operating at full load let engine warm up for a few minutes Idling Do not let the engine idle for prolonged periods as this may result in carbon build up foul the spark plug or cause flood ing Engines put under severe strain may continue running after the ignition is turned off To stop the engine under these conditions shut off the air supply by closing the choke Stopping Procedure Release the throttle to allow engine to idle Turn switch to off position Do not use the choke to stop the engine This can result in carburetor flooding making it very difficult to restart Safety Precautions 1 Never add fuel while the engine is running as spilled fuel might ignite on contact with hot engine surfaces Stop engine and allow to cool 2 Always be sure ignition switch is in off position before working on engine 3 Make sure all safety shields or guards on engine and driven equipment are in proper position and securely fastened 4 When starting keep hands feet and clothing at a safe distance from moving parts 5 Do not operate the engine in closed buildings unless ex haust pipe is vented to the exterior Fuel Mixture Gas Oil Ratio Gasoline Required Ounces Of Oil 5 Gallons 4 Gallons 3 Gallons 2 Gallons NOTE Mix gasoline 90 octane minimum with SAE 30 40 air cooled engine oil Premix thoroughly before pouring int
23. sing and the oil seal for cuts or other visible damage Pass the fan housing over the crankshaft and avoid hitting the sharp edges of the keyway Adjust the housing against the crankcase and insert the four screws with the special Allen Head tool Tighten Allen Head Screws in crosswise pattern 6 Intake Manifold Coil Cover Install intake manifold assembly and gasket tighten the two upper manifold nuts Connect the ignition coil wires to terminals Replace coil cover making sure to reconnect the No 2 cylinder ground wire brown Fasten spark plug wire clip to fan housing 7 Upper Axial Fan Belt Pulley Assembly Insert Nilos ring first tapered spacer dished side towards fan first pulley half four adjustment shims second pulley half second tapered spacer dished side facing outward washer and nut Note block impeller with a punch when tightening nut i 8 Flywheel Magneto Ignition Timing Align magnetic flywheel with keyway insert and tap key into position Lighily tighten flywheel nut For timing details see Ignition Timing Procedure 9 Cylinder Heads Install cylinder head gaskets f piston is below the cylinder by 0 008 use cylinder head 438 07 006 00 If piston is above cylinder by 0 008 use cylinder head 438 07 007 00 The gap between the piston and cylinder head must be measured after assembly This is done by introducing a thick piece of solder into the spark plug hole at a 90 angle to the crankshaft with the en
24. t procedure for cylinder No 1 except do not rotate armature plate If timing of No 2 cylinder is required adjust the breaker point gap only NOTE Rockwell Jlo axial fan twin cylinder engines have timing marks cast on the fan housing This makes it possible to check timing while the engine is running Use an automo tive type strobe light and aim at the timing marks If the notches on the flywheel are not in alignment with the marks on the fan housing the engine is out of time Note that there are two notches on the flywheel one for each cylinder This permits instant timing check of both cylinders A quick timing check can also be performed with the engine not running With centrifugal weight in retard position attach the timing tester to the coil wire terminals and slowly turn the engine over by pulling on the recoil starter Once the notch on the flywheel is aligned with the mark closest to the center the timing tester light should dim If the light does not dim when both timing marks are in alignment the engine needs retiming Slider Adjustment cam CAES wl 2 VE B a 7 o Y 24 WA a li TX Armature plate mounting screw Feeler gauge between the points Rotating cam Fiyweight for ignition timing adjustment Oxide magnet with pole shoe Stator Plate Lockscrew F Courtesy of Robert Bosch GMBH Specifications Model LR 440 2 2F 440 3 Twin Cylind
25. trokes for every revolution of the crankshaft As the piston moves upward in the cylinder Illustration A it draws the fuel air mixture into the lower crankcase while INTAKE at the same time compressing the fuel already in the com pression chamber above As the piston nears T D C the spark plug ignites the compressed fuel and the burning fuel expands and forces the piston downward on its second or power stroke Illustration B In this downward stroke the piston not only turns the crankshaft but compresses a new charge of fuel in the crankcase while continuing downward clearing the exhaust ports Illustration C in the cylinder wall to release the burned gasses through the ports and out into the exhaust system The piston continues downward to uncover the transfer port and release the compressed fuel charge into the cylinder where it displaces the remain ing burned gasses and forces them out through the exhaust ports illustration D Because lubrication of 2 cycle engines depends on mixing predetermined amounts of oil and fuel it is extremely impor tant that good quality oil be thoroughly mixed with fuel and in proper proportions While there are different engines as well as different oils requiring different fuel mixtures the correct oil fuel ratio required for Rockwell JLO engines is 20 to 1 Use of little oil may cause engine over heating piston or cylinder scoring and eventual engine seizure or failure Too much oil on the

2F-440-3 Service Manual

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