Service Manual. For 2-CYCLE ENGINE FUNDAMENTALS EXHAUST SYSTEM. DISASSEMBLY AND ASSEMBLY INSTRUCTIONS OF BASIC ENGINES INCLUDING RECOIL STARTERS

Transcription

1 /773 r:.,. ~ ~... SVM :-;\. Servie Manual For.~ ROCKWELL ~xial Fan Cooled ~Twin Cylinder Engines Models 2F-400-6, 2F~440-3; 2F CYCLE ENGINE FUNDAMENTALS CARBURETION IGNITION EXHAUST SYSTEM. DISASSEMBLY AND ASSEMBLY INSTRUCTIONS OF BASIC ENGINES INCLUDING RECOIL STARTERS RING GEAR INSTALLATION IGNITION TIMING PROCEDURE SERVICE TOOLS

2 2-Cyle Engine Fundamentals The Rokwell 2-yle ai r.:.ooled gasoline engine, partiularly the axial fan-ooled twin ylinder engine, has beome very popular today for snowmobiles. It is uniquely qual i fied for this appliation beause of its high power output, light weight and ease of lubriation, with fewer moving parts than other onventional 2-yle and 4-yle engines. INTAKE However, in order to get the best possible use and ensure that it retains its high degree of dependability and endurane, it must reeive proper are and maintenane. Therefore, it is neessary for us to know something about the basi fundamentals of this engine and how it funtions. OPERATION The Rokwell 2-yle Twin Cylinder engine is of the loop-savenged third port design ty pe, the most widely used design today. It uses a mixture of gasoline, oil and air for ombustion, lubriation and ooling. It fires on every stroke of eah piston. There are two power strokes for every revolution of the rankshaft. EXHfUST TRANSFER As the piston moves upward in the ylinder it draws the fuel /ai r mixture into the rankase through the intake manifold while at the same time ompressing fuel that has been fored into the ombustion hamber. (Illustration A) As the piston nears top dead enter the spark plug is fired and the ompressed fue I /air mixture burns and expands thereby foring the piston downward on a power stroke. As the downward stroke of the piston turns the rankshaft, it also starts to ompress the fuel/air mixture in the rankase and, simultaneously, opens the exhaust port and loses the intake port. (Illustrations Band C) After the exhaust port is fully open and the intake port is fully losed, further piston travel starts to open the transfer ports. The ompressed fue I I air mixture from the rankase then travel-s up the transfer ports and into the ombustion area. After most of the burned exhaust gases have left the ylinder, an inoming harge of fuel/air mixture savenges the ombustion area giving it a fresh harge and the yle is then repeated. (li lustration D) Beause lubriation is dependent on the mixing of oi 1 and fuel, it is extremely important that good quality oil and gasoline are properly mixed. The proper gasoline/oi l ratio is 20:1. This ratio is reommended to prevent possible engine overheating, piston or ylinder soring, or eventual engine seizure. Too muh oil and not enough gasoline an lead to inomplete ombustion, ausing fouled plugs, arbon build-up and muffler logging. 2 Tuning Courtesy of Donaldson Muffler Co. 0

3 CARBURETION In order to atomize the oil/fuel mixture and mix it with proper proportions of air flowing to the intake port or intake manifold, it is neessary to utilize a arburetor. Carburetor design is based on the Venturi priniple whereby a gas or liquid flowing through a restrited or neked-down passage inreases in veloity and dereases in pressure. Rokwell 2 ylinder, axial fan ooled twin ylinder engines use only diaphragm type arburetors. IGNITION The ignition system provides the high voltage eletrial energy whih flows aross the spark plug eletrode gap to reate ignition spark. Rokwell engines are equipped with a flywheel magneto type ignition. This system generates and transforms eletrial energy into high voltage and delivers it to the spark plug at the proper time for ignition. SPARK PLUG Termanal nut Insulator Term.nal bolt Donaldson The spark plug provides the el etri spark neessary for ignition of the ompressed fuel /air mixture in the ombustion hamber. There are many sizes and types of spark plugs. Rokwell Twin Cylinder engines use the long reah type spark plug. Spark plug tip temperatures are extremely important for proper engine operation, therefore, plugs should be seleted in aordane with th.e reommendations that are listed in this manual under "Speifiations" Cnmp1ng nng Gasket seal Center eletrode Sr.ew thread Ground eletrode EXHAUST SYSTEMS Fl~heel Magneto SELECTION Seletion of an exhaust system (inluding exhaust manifold, intermediate pipes, elbows and muffler), is a result of thorough test proedures involving measurement of fuel onsumption, horsepower and noise level. Contrary to popular belief, the exhaust system is not only for quieting the engine, but also serves to inrease horsepower output (by as muh as 25%). Changes made to the original equipment exhaust system by hanging any omponent in the system an result in loss of power and /or severe engine damage. For these reasons, intermediate lengths of pipe between the ylinder and the muffler are partiularly ritial. TUNED MUFFLERS Tuned mufflers allow the engine to exhaust its spent harge into an adequate volume and properly mathed muffling system. More important, the mufflers are tuned, inorporate designs th at suk the exhaust gas from the ylinder allowing fuel and air to rapidly repl ae it and also "ram" over-savenged fuel and air mixture from the exhaust pipe bak into the ylinder using sound waves an d sound energy. This is aompl ished at the speed of sound whih allows the engine to produe higher torque at higher RPM' s. 3 HOW TlJNING WORKS The megaphone effet of the expanded intake tube savenges exhaust gas from th e ylinder allowing rapid rep laement of the fuel/air mixture from the rankase. Refleted sound Waves and sound energy stop oversavenging and return fue l /air mixture t o the ylinder. It gives a superharging effet even though it operates from the exhaust rather than the intake side. Over-savenging is also retarded by moderate muffler bak pressure. Silening is aomplished after power is maximized by aoustial paking in the resonator outlet tube plus hambering and baffling whih gives an effetive 2-pass muffler design.

4 ROCKWELL Twin Cylinder Engines Models 2F , 2F , 2F Disassembly and Assembly Proedure DISASSEMBLY A. Reoi I Starter Remove four srews holding the reoi I assembly to the fan housing. (Note, two styles of starter assemblies and related parts used.) B. Lower Fan Pulley and Carrier Assembly Remove the three hexhead srews on the arrier. Remove the dust seal (if used), arrier, lower pulley assembly and V-belt. C. Upper Fan Belt Pulley Assembly Aluminum Reoil A Steel Reoil Keep the impeller from turning by inserting a 3/16" dri II or a suitable punh through the fan housing and into the impeller body. With a 17 mm. box wrenh, loosen and remove the fan nut, then take off washer, pulley halves and spaers. 4

5 D. Flywheel Magneto Remove the rankshaft nut using a 27 mm. soket wrenh. Pull the flywheel by attahing a speial flywheel pu l ler to the magneti flywheel flange using the three puller bolts supplied. Srew the three bolts through the puller into the f lange and tighten evenly. Tighten the enter bolt in the puller until it touhes the rankshajt. With a soket wrenh tighten the bolt lokwise unti I the flywheel loosens on the rankshaft. Note: It is important that are be taken in removing the flywheel assembly beause the positioning key loated in the keyway may stay in its original position and thereby ause damage to the advane mehanism. A small iepik or srewdriver may be used to loosen and remove the key. D D E. External Ignition Coil Cover Remove the four manifold nut s and spring washers. Remove the two outboard oi I mounting srews. Coi I plate, eletrial onnetors and intake manifold an now be removed. F. Fan Housing, Armature Plate Assembly Remove srew holding spark plug wire braket to fan housing. With an Allen wrenh (5 mm. or 6 mm.), loosen the four mounting bolts holding fan housing to rankase. It is advisable that the head of these bo lts be tapped with a flat punh and hammer before removal is attempted. Remove fan housing by pulling evenly away from rankase and towards end of rankshaft. E To remove the armature plate, f irst unplug the wires that I ead to the o i Is and into the onnetor housing. (Note the olor oding of the wires.) Remove the armature plate mounting srews. Remove armature plate assembly and wires, as a unit, from fan housing. Remove the fan by tapping the threaded end of the fan shaft with a soft-nosed hamme r. With flat punh and hammer, tap on inner bearing rae of furthest bearing in the housing, (the spaer between the bearings wi II move sideways allowing aess to the inner rae). Care should be taken that Ni los rings are not misplaed during shaft removal. E F. F 5

6 ROCKWELL Twin Cylinder Engines Models 2F , 2F , 2F Disassembly and Assembly Proedure ) DISASSEMBLY G. Spark Plugs Remove spark plugs with spark plug wrenh. H. Cylinder Heads Remove head nuts with a 17 mm. box or soket wrenh. The ylinder head s and ylinders should be marked (I or II) before head removal from ylinder. Remove ylinder head gaskets and disard. I. Cylinders (See footnote) Remove the eight ylinder base nuts using a 13 mm. soket wrenh and remove the eight spring. washers. The ylinders may now be arefully removed from the rankase assembly. F NOTE: If removal of just the ylinders is required, are sh ould be taken that the rankase sealant is not disturbed. The removal of the PTO ylinder will a llow the plaement of two bolts with retaining nuts and flat washers so that ontinued pressure an be applied to both rankase halves. These bolts must be installed and tightened in F opposite sides of the rankase assembly. The seond ylinder may now be removed. G J. Piston and Wrist Pin Mark eah piston with the number orresponding to its ylinder head and ylinder. With needle 'nose pliers remove the four irlips from the pistons. Gently tap the wri st pin out of the piston with the aid of a 1/2" flat punh and a hammer. Care should be taken not to damage the needle bearing assemblies. H 6 J J

7 K. Crankase To separate the rankase halves, hold the upper portion of the rankase assembly in one hand, lifting the entire rankase slightly, and tap the end of the rankshaft with a soft-nosed hammer. The rankase wi II then separate and the rankshaft may be removed. L. Crankshaft Bearings To remove rankshaft bearings use the speial bearing puller assembly. Slip the puller half shells around the outer bearing rae and around the puller assembly. Slide the retaining ring over the half shells. Using two 27 mm. wrenhes, turn the enter bolt lokwise with one wrenh and use the seond wrenh to hold the puller body. Before removing the PTO side rankshaft bearing, insert a 1/2"-20UNF bolt 1/2" long to protet the internal thread of rankshaft. J J K, o. L L 7

8 ROCKWELL Twin Cylinder Engines Models 2F , 2F , 2F Disassembly and Assembly Proedure ASSEMBLY A. Crankshaft Bearing Heat the rankshaft bearings in oil to a temperature of 180 F. Pl ae the bearing over the end of the ranksh aft using a hollow pipe the same diameter as the inner bearing rae. Tap the end of the pipe with a hammer thus seating the bearing firmly against the mating surfae of the rankshaft ounterweight. Repeat the proedure for the bearing on the other end of the rankshaft. B. Crankase,. : In spet and lean both halves of the rankase~ All original seal ing adhesive must be removed and surfaes shou ld be inspeted for bu rrs and other foreign materials and these should be removed. The proper seal ant material (Piiobond) should now be spread on all seal ing surfaes. The sealing surfaes are as follows: rankase mating surfaes, bearing seats and PTO shaft seal seat. Before installing rankshaft into rankase lower half it wi II be neessary that all bearing outer surfaes (labyrinth and seals inluded) be wiped lean and free of oi I and f oreign material so that proper sealing wi II our. After installing PTO thrust washer and oil seal (inside groove of oil seal oated with a l ight grease) plae the rankshaft arefully into the lower rankase half and properly position all omponents. Plaement of t he upper rankase half may now be made. A small soft-nosed hammer may be used to tap down in various areas of the upper rankase half so that proper fit and alignment an be obtained. It is suggested that the two rankase holding bolts be now plaed in holes opposite eah other in the PTO ylinder bolt holes and fastened finger tight. B - ~ 8 <

9 C. Piston, Cylinder and Cylinder Heads The pistons must be lean and free from arbon deposits and the piston rings must fit freely in their respetive grooves. (Top ring is marked " TOP".) The proper piston for its orresponding ylinder may now be plaed on the rankshaft onneting rod. The arrow on the piston rown must point t oward the exhaust of the engine. The piston pins, needle bearings, hek plates and irlips may now be installed in their respetive positions. Be sure that the eire! ips fit properly in the outer grooves of the piston pinhole. Install the blak graphite base gaskets on the ylinder hold-down studs and position properly against the ylinder flange of both ylinders. Using a wooden holding blok under the piston on the fan side of the engine, plae the orresponding piston rings into position and with the use of a ring ompressor lower the y I i nder over the piston. Remove the wooden blok and install base spring washers and nuts finger tight. (It of ourse is neessary that a small amount of oil be applied to the rings and that the rings fit properly to the loating pins.) The PTO ylinder may now be installed after removing the two holding bolts from the rankase. Follow the same proedure as outlined for the fan side ylinder. Using a straight edge on the fan side mating surfae, align upper and lower rankas.e halves. Temporarily install the intake manifold (without intake gasket installed), and tighten manifold nuts. Cylinder base nut may now be torqued to 16 to 18 ft/lbs as outlined on speifiation page. The proper piston height may now be measured at the top of the ylinder sleeve. The piston outer edge must not protrude above the ylinder (piston in TDC). If the piston outer edge protrudes above the ylinder sleeve surfae a thiker base gasket must be installed. (See Page 23 for dimensions and olor oding.) It is important that only one ylinder at a time be adjusted or the rankase will separate and loose its seal. The respeti ve ylinder heads and new gaskets are now to be installed. Be sure that the wide portion of the inner metal flange of the head gasket be installed towards the ylinder head surfae. Torque the ylinder head nuts to 28 to 32 ft/ lbs as outlined on speifiation page. 9

10 ROCKWELL Twin Cylinder Engines Models 2F , 2F , 2F Disassembly and Assembly Proedure ) Assembly D D. Fan Hou sing, Impel ler and Bearings The hub hol ding the fan sh aft bearings must be leaned thoroughly, the irlips and bearing spaer must now be installed. (Use a medium grease to hold spaer in plae). Pak bearings with medium grease and install them into the housing with the sealed surfaes outward. Install the fan, shaft and Nilos rings. E. Fan Housing, Armature Plate Remove the oil seal from the fan housing and install the new seal. Lubriate the inner groov e of the oil seal with a light grease. Remove the fan housing hub 0-ring, lean area thoroughly, instal l new 0-ring and apply seal ant material (Piiobond) around 0-ring surfae. Install the armature plate wires through the hole in the fan housing and install the armature plate assembly and hold- down srews with lok wash ers and flat washers. Plae the fan housing assembly arefully over rankshaft and position to rankase assembl y. Be sure that grommet holding i gnition wires is properly installed. Install the four Allen head srews and lokwashers in housing and tighten down ev enl y until fan housing is against rankase assembly. Align fan housing to the ylinders and torque srews to 16 to 18 ft/lbs. Connet ignition wires to external ignition oil and to onnetor housing. Be sure ground wires are in proper position. Install ignition able braket on fan housing. D D E 10 E E

11 F. Int ake Manifold and Coil Cover Install blak graphite intake gaskets, intake manifold, oil over plate and onnetor housing. Install the four spring washers and nuts and install the two outboard oi I mounting srews. (Be sure oil ground wires are fastened.) Torque manifold nuts evenly to 16 to 18 ft/ I bs. G. Upper Fan Pulley Assembly Install the tapered washer against the Niles ring, then the pulley half, shims, seond pulley half, tapered was her, lok washer and nut. Use a 3/16" dri II bit or suitable punh to hold the fan assembly and tighten the shaft nut slugly. H. Flywheel Magneto Chek the advane mehanism for free operation, lubriate inside am surfae (grooved area). Slide assembly over rankshaft and align keyways. Install flat key, lok washer, nut and tighten seurely. Follow timing proedure setion. H 11

12 ROCKWELL Twin Cylinder Engines Models 2F , 2F , 2F Disassembly and Assembly Proedure Assembly H I. Lower Fan Pulley Assembly Install pulley half, belt, seond pulley half, reoil arrier, lok washers and bolts. Tighten bolts evenly while rotating rankshaft. Proper tension of the fan belt should be as follows: using the thumb and the index finger squeeze the belt together at approximately the enter distane of the pulleys. The defletion of the fan belt should be 1 / 8" eah side. Proper adjustment an be made by adding or removing shims between the upper pulley halves. ) J. Reoil Starter Install the respetive reoi I starter assembly and be sure the proper fit is obtained in the fan housing (shoulder and I ips) before the hold-down hardware is tightened seurely. 12

13 ROCKWELL Twin Cylinder Engines Models 2F , 2F , 2F Disassembly and Assembly Proedure -RECOIL starter FIRST VERSION (Aluminum)- SECOND VERSION (Steel) DISASSEMBLY -FIRST VERSION (Aluminum) A. Remove the three srews holding the over plate. Remove the over plate, paper gasket and pawl assembly (springs and aps inluded). Remove the intermediate plate. B. Remove the handle assembly from reoi I rope and hold rope seure. With the starter housing lying flat on the work surfae, plae the palm of your hand on the hub of the rope drum and hold the starter housing with your thumb and your fingers. Release the rope and ontrol the unwinding ation of the rope drum by applying palm pressure to the rope drum hub. Insert a suitable punh or a srewdriver into round hole near enter of rope drum and push down firmly on reo i I spring eyelet. Lift up rope drum assembly.. Reverse starter housing position and tap housing assembly on work surfae to release the reoil spring from the housing. 13

14 ROCKWELL Twin Cylinder Engines Models 2F , 2F , 2F Disassembly and Assembly Proedure-RECOIL starter ) ASSEMBLY- FIRST VERSION (Aluminum) A. Clean and thoroughly inspet all parts of the reoi I starter assembly and remove reoi I rope from rope drum. B. Plae end of spring on retaining pin in starter housing. The spring may now be wound into the housing by rotating the housing lokwise while firmly applying thumb pressure on the spring as it is being wound into the housing assembly. Lubriate reoi I spring and enter hub with I i ght grease. C. The rope drum may now be installed with the use of a small punh or suitable srewdriver inserted through the round hole near the enter of the rope drum. This tool should be plaed into the spring eyelet and the rope drum be positioned on reoil housing nub. The spring must fit into the holding slot of the rope drum as it is fitted downward into position. D. The rope drum must be wound ounterlokwise to the fully tight position and then baked off up to one turn so that the rope an be pi aed through the rope retaining holes and rope outlet in th e housing. Plae rope through drum and housing areas and properly position rope retainer into rope drum. Al low rope to reoil so that spring t ension is redued. Install handle assembly, retaining ring and retaining key. B B ) E. Install the intermedi ate plate; lubriate starter pawls, spring aps and install into starter assembly. (Be sure there is enough lubriation on the intermediate plate around the starter pawl area.) F. Replae gasket; lubriate over plate on underneath side and install into housing with three srews and lok washers. 0 ' F ~--~ ',I 14

15 ROCKWELL Twin Cylinder Engines Models 2F , 2F , 2F Disassembly and Assembly Proedure-RECOIL STARTER DISASSEMBLY- SECOND VERSION (Steel) A. Remove the Allen head srew, flat washer, spei al onfiguration flat washer, pawl over retainer, torsional spring over, pressure spring and the three starter pawls. B. Remove handle assembly from reoil rope and hold rope seure. With the starter housing lying flat on the work surfae, plae the finger tips against the outer area of the rope drum, rerease the reoi I rope and allow rope drum to unwind slowly. C. Insert a suitable punh or srewdriver into the round hole near the enter of the rope drum and push down firmly on the reoi l spring eyelet. Lift up rope drum assembly. D. Reverse starter housing position and tap housing assembly on work surfae to rerease the reoil spring from the reoil housing. The outside plasti buffer shim may also ome out at this time. A-.. ~......,. B 15

16 ROCKWELL Twin Cylinder Engines Models 2F , 2F , 2F Disassembly and Assembly Proedure-RECOIL starter ) ASSEMBLY- SECOND VERSION (Steel) A. Clean and thorough I y inspet all parts of the reoi 1 starter assembly and remove reoi I rope from rope drum. B. Replae plasti buffer shim with flat side up. C. Plae end of spring onto retaining pin in the starter housing. The spring may be wound into the housing by rotating the hou sing lokwise while applying thumb pressure to the spring as it is being wound into the housing assembly. Lubriate reoi I spring and enter hub with light grease. D. The rope drum may now be installed with the use of a small punh or srew driver inserted through the round hole near the enter of the rope drum. This tool should be plaed into the spring eyelet and the rope drum be positioned on the reoil housing hub. The spring must fit onto the holding pin of the drum as it is positioned downward on the housing hub. E. The rope drum must be wound ounterlokwise to the fully tight position and then baked off up to one turn so that the rope an be plaed through the rope retaining hole and rope outlet in the housing. Plae rope through drum and housing area and properly position rope retainer into rope drum. Allow the rope to reoi I so that spr ing tension is redued, install handle assembly, retaining ring and retaining key. D ) F. Lubriate the starter pawl area on the rope drum and the starter pawls with a light grease. Position the three starter pawls, install the pressure spring, the torsional spring and the pawl over retainer. The speial onfiguration flat washer must now be fitted onto the shaft and the flat washer and Allen head srew be installed and tightened seurely. F... 16

17 ROCKWELL Twin Cylinder Engines Models 2F-440-3, 2F Ring Gear Kit Installation and Removal INSTALLATION A. Remove the PTO side oil seal by using an L shaped hook, inserting it on the inner lip of the oil seal. Be areful not to damage rankshaft sealing surfae. Apply pulling pressure on the tool until oil seal begins to ome out of rankase. Rotate tool to various positions around the oil seal lip, perform pulling operation until oil seal is removed. B. Lubriate inner groove of oil seal with light grease and position on rankase. Using a small ball peen hammer, gently tap oil seal on front fae in various loations until oil seal outer fae is flush with rankase. 0 0 C. Install ring gear hub assembly onto rankshaft and push firmly until ontat is made against inner bearing rae. 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 faing outward; then plae the I arger ring next to the smaller ring with the tapered end faing the engine. E. Plae the pressure flange onto the rankshaft, install the four Allen head srews and lokwashers and tighten evenly rosswise until snug. Torque to speifiations as indiated in speifiation hart. REMOVAL: For ring gear removal reverse above proedure (steps E through A). E 17

18 20 ROCKWELL Twin Cylinder Engines Model 2F Ring Gear Kit Installation and Removal ) INSTALLATION ENGINE MODEL 2F 400M6 A. Remove the PTO side oil seal by using an L-shaped hook, inserting it on the inner lip of the oil seal. Be areful not to damage rankshaft sealing surfae. Apply pulling pressure on the tool until oil seal begins to ome out of rankase. Rotate tool to various positions around the oi l seal lip, perform pulling operation until oil seal is removed. B. Lubriate inner groove of oil seal with light grease and position on rankase. Using asmall ball peen hammer, gently tap oil seal on front fae in various loations until oil seal outer fae is flush with rankase. A. Plae ring gear onto rankshaft and install ring gear installation tool. Squirt a few drops of light mahine oil on rankshaft in oil seal area. Push the ring gear into position with the installation tool. Be sure ring gear makes ontat with the inner bearing rae. Remove installation tool. REMOVAL: D. For ring gear removal thread a 1 /2" M UNF bolt 1/2" long into rankshaft end, use the flywheel puller and attah with 8 mm. hex srews evenly to ring gear. With one wrenh keep puller from rotating, while turning enter bolt of puller lokwise with -seond wrenh, thereby pulling off ring gear. ) E. Remove oil seal as desribed in paragraph "A". D 18

19 ROCKWELL Twin Cylinder Engines Models 2F , 2F , 2F TIMING PROCEDURE NOTE: Reoil starter, arri er, lower pulley assembly and spark plugs should be removed before beginning timing proedure. A. Install the dial indiator assembly into spark plug hole of fan side ylinder (ylinder No. 2). B. Attah the negative lead of Ohmmeter to engine ground. Attah the positive lead of Ohmmeter to No.2 Cylinder terminal in onnetor housing. C. Loosen armature pi ate hold-down srews and rotate armature plate ounterlokwise unti I the srews are positioned in the enter of the slotted holes in armature plate. Tighten hold-down srews seurely. D. Rotate flywheel ounterlokwise until dial needle on indiator reads TDC. Adjust dial to read.006" and tighten loking braket on dial indiator. Move entrifugal weight in magneti flywheel assembly to the fully advaned position, plae the sele~tor knob on the Ohmmeter to read "R x.1". E. Rotate the flywheel ounterlokwi se while wathing the dial indiator. The needle on the dial indiator must make one full revolution ounterlokwise and stop at zero. The breaker point for the No. 2 ylinder at this point wi ll just make ontat (losing). This wi II show on the Ohmmeter beause the need I e wi II move to the left. If this ondition does not our the breaker point needs adjusting. F. Breaker Point Adjustment Loosen the srew holding the breaker point to the armature plate and adjust the breaker point so that the above reading (dial indiator and Ohmmeter) an be obtained, tighten srew. It is possible that the operation be repeated several times so that the orret readings are obtained. This is a must for proper engine and ignition operation. Repeat above operation on PTO side ylinder (ylinder No. I) and be sure to obtain the same readings. G. After both breaker points have been adjusted properly it is reommended th at the stati timing be heked. The proper method is as follows: with the piston in TDC set the dial of the indiator to.019" and follow proedure E with entrifugal weight in the retarded position. A reading of zero on the dial indiator when the point makes ontat indiates that the advane mehanism is operating properly. All tests are performed with Merotroni timing equipment. 19

20 ROCKWELL Axial Fan Cooled Twin Cylinder Engines Models 2F F F Speifiations ' '. Desription 2F Engine Model 2F F Bore 2.658" (67.5mm) 2.559" (65.0mm) 2.658" (67.5mm) Stroke 2.362" (60mm) Displaement in 428 Compression Ratio (atual) 9.5:1 Ignition System :1 Bosh Flywheel Magneto :1 Lighting Coi I Voltage and Output 12V 75W 12V 120W 12V 120W *Timing BeforeTDC (Centrifugal Weight Advaned) -.106" Timing Before TDC (Centrifugal Weight Retarded) _.018" to.020" 1 06".018" to.020".106".018" to.020" Breaker Point Gap _,.014" to.018" Spark Plug Thread 14mm. x / 4" reah Spark Plug Gap 020" (0.5mm.).020" (0.5mm. ).020" (0.5mm.) Spark Plug- Bosh (Original Equipment) W260T2 W260T2 W260T2 Spark Plug- A-C (Original Equipment) S41-XLR S41-XLR S41-XLR Spark Plug- Champion (Original Equipment) N- 3 Type of Engine Cooling N-3 Axial Flow Fan N-3 Rotation of Crankshaft Carburetor Counterlokwise (PTO side) Walbro Fuel / Oil Ratio 20:1 Gasoline 90 otane, minimum (lead free not aeptable) T ype of Oil Speial 2-Cyle Snowmobile Oil *Do not exeed indiated advane, as this will result in severe engine damage. ' 20

21 ROCKWELL Axial Fan Cooled Twin Cylinder Engines Speifiations TORQU E SP ECIFICATIONS 2F F F Cylinder Head Nuts 28 to 32 ft. / lbs. Cylinder Base Nuts 16 to 18 ft. / lbs. Flywheel Nut Int ake Manifold Nuts 44 to 50 ft./lbs. 56 to 72 ft.! I bs. 16 to 18 ft. / lbs. 56 to 72 ft./ I bs... Fan Housing Srews 16 to 18 ft./ lbs. Fan Wheel Nut 22 to 24 ft./lbs. Ring Gear Srews (6mm.) 6 to 7 ft. / lbs. not appliable not app l iable Ring Gear Srews (8mm.) 10 to 12 ft./lbs. not appliable 10 to 12 ft. / lbs. Tightening Sequene for Cylinder Base Nuts PTO Side 8 0 () 8 -. ' T ightening Sequene for: ' ' Cylinder Head Nuts, Fan Housing, Ring Gear Flange, Intake Manifold and Reoi I Starter Clamps 0 8 ' ' J 21

22 Sorpion In. Crosby,Minnesota SV ~l /72 (3. 5M) Printed in U.S.A.