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Wacker Neuson WM 90, Repair Manual

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Wacker Neuson WM 90 Repair Manual Download Page 31

WM 90

Theory of Operation

wc_tx000388gb.fm

31

WM 90 engines use a diaphragm-type carbu-
retor.

The air cleaner is a heavy-duty three-stage 
type with cyclonic precleaner.

An automatic decompression mechanism (a), 
that opens the exhaust valve before the piston 
reaches maximum compression, is assembled 
on the camshaft for easy starting. During 
engine operation the decompression system is 
overpowered by centrifugal force and com-
pression is fully utilized to produce power.

Component Illustration

Component Description

wc_gr001881

wc_gr002032

wc_gr001883

a

Summary of Contents for WM 90

Page 1: ...www wackergroup com Engine WM 90 REPAIR MANUAL 0160157en 002 0207 0 1 6 0 1 5 7 E N...

Page 2: ......

Page 3: ...the documents please contact Wacker Corporation to order a replacement Damage caused by misuse or neglect of the unit should be brought to the attention of the operator to prevent similar occurrences...

Page 4: ...qualified and rated by the United States Forest Service for this purpose In order to comply with local laws regarding spark arresters consult the engine distributor or the local Health and Safety Adm...

Page 5: ...Data 23 3 1 Specifications 23 3 2 Performance 24 4 Theory of Operation 25 4 1 Application 25 4 2 Recommended Fuel 25 4 3 Before Starting 25 4 4 To Start 26 4 5 To Stop 27 4 6 Component Descriptions 2...

Page 6: ...Cover 49 7 9 Removing Camshaft and Tappets 50 7 10 Removing Connecting Rod and Piston 51 7 11 Removing Crankshaft 52 7 12 Removing Intake and Exhaust Valves 53 8 Reassembly Procedures 54 8 1 Notes on...

Page 7: ...e Carburetor 75 9 6 Carburetor Disassembly Procedure 78 9 7 Carburetor Inspection 79 9 8 Carburetor Reassembly 79 9 9 Carburetor Adjustments 80 10 Recoil Starter 81 10 1 Recoil Starter Disassembly 81...

Page 8: ...scribing the operation and maintenance of emission control systems The following instructions and procedures must be followed in order to keep the emissions from your Wacker engine within the emission...

Page 9: ...Remember that this schedule is based on the assumption that your machine will be used for its designed purpose Sustained high load or high temperature operation or use in unusually wet or dusty condit...

Page 10: ...equipped to conform at the time of initial sale to all applicable regulations of the U S Environmental Protection Agency EPA and that the engine is free of defects in materials and workmanship which...

Page 11: ...ent unless they were made by the service dealer authorized by Wacker during a warranty repair alteration accident failure to use the recommended fuel and oil or not performing required maintenance ser...

Page 12: ...ANCE REPLACEMENT OR REPAIR OF EMISSION CONTROL DEVICES AND SYSTEMS MAY BE PERFORMED BY ANY REPAIR ESTABLISHMENT OR INDIVIDUAL HOWEVER WARRANTY REPAIRS MUST BE PERFORMED BY A SERVICE DEALER AUTHORIZED...

Page 13: ...follow this symbol to avoid possible injury or death DANGER indicates a hazardous situation which if not avoided will result in death or serious injury WARNING indicates a hazardous situation which i...

Page 14: ...ded by Wacker Damage to equipment and injury to the user may result 2 1 5 NEVER leave machine running unattended 2 1 6 NEVER tamper with or disable the function of operating controls 2 1 7 NEVER use c...

Page 15: ...g Internal Combustion Engines Internal combustion engines present special hazards during operation and fueling Read and follow the warning instructions in the engine owner s manual and the safety guid...

Page 16: ...engine is flooded or the smell of gasoline is present A stray spark could ignite the fumes 2 3 7 DO NOT use gasoline or other types of fuels or flammable solvents to clean parts especially in enclose...

Page 17: ...WM 90 Repair Safety Information wc_si000143gb fm 17 2 4 Label Locations...

Page 18: ...molded in label contains important safety and operating information If it becomes illegi ble the cover must be replaced Refer to the Parts Book for ordering information DANGER Engines emit carbon mono...

Page 19: ...filtered gasoline fuel WARNING Hot surface WARNING Serious injury if struck by compressed spring or cover If the spring system cover is removed improperly the springs can eject Guaranteed sound power...

Page 20: ...nit Please record the infor mation found on this plate so it will be available should the nameplate become lost or dam aged When ordering parts or requesting ser vice information you will always be as...

Page 21: ...Operating Labels Wacker machines use international pictorial labels where needed These labels are described below Label Meaning Turn the engine switch to the ON position Close the choke Pull the rewi...

Page 22: ...Information WM 90 Repair wc_si000143gb fm 22 Throttle control lever Turtle Idle or Slow Rabbit Full or Fast Fuel valve Closed Open Engine stop button Press to stop engine Choke 0 Open l Closed Label M...

Page 23: ...BM4A or BMR4A Electrode Gap mm in 0 6 0 7 0 023 0 028 Cylinder Head Compression cold kg cm2 psi 8 0 9 7 120 140 Air Cleaner type Three stage with cyclonic precleaner Engine Lubrication oil grade SAE...

Page 24: ...hnical Data WM 90 wc_td000143gb fm 24 3 2 Performance Ref Description Ref Description a Maximum torque d Recommended horsepower range b Continuous rated horsepower e Output c Maximum horsepower f Torq...

Page 25: ...ther structures 4 2 Recommended Fuel This engine is certified to operate on automotive unleaded gasoline Use only fresh clean gasoline Gasoline containing water or dirt will damage fuel system 4 3 Bef...

Page 26: ...starts 4 4 5 On engines equipped with the low oil shutoff switch see section Low Oil Shutoff Switch for additional information Note First time use engines recently serviced run out of fuel or not use...

Page 27: ...cylinder liner made of special cast iron is molded into the aluminum casting The crankcase has a mounting sur face on the output shaft side where the main bearing cover is attached The main bearing c...

Page 28: ...nd carries two compression rings and one oil ring The piston rings are made of special cast iron The profile of the top ring and the second ring are shown in the illustration The oil ring is a three p...

Page 29: ...ve area for optimum cooling Reference intake a exhaust b The cylinder head is an aluminum die casting which utilizes wedge type combustion cham ber for high combustion efficiency The governor is a cen...

Page 30: ...rotating and sliding parts are splash lubricated by the oil splasher a on the con necting rod The ignition system is a transistor controlled magneto system which consists of a flywheel a and an ignit...

Page 31: ...matic decompression mechanism a that opens the exhaust valve before the piston reaches maximum compression is assembled on the camshaft for easy starting During engine operation the decompression syst...

Page 32: ...Theory of Operation WM 90 wc_tx000388gb fm 32 4 7 Cross Section Across Shaft wc_gr001884 2 3 7 8 8 9 9 10 11 12 13 1 1...

Page 33: ...ents See Graphic wc_gr001884 Ref Description Ref Description 1 Cylinder head 9 Main bearing cover 2 Piston pin 10 PTO shaft 3 Ignition coil 11 Piston ring 4 Blower housing 12 Piston 5 Recoil starter 1...

Page 34: ...Theory of Operation WM 90 wc_tx000388gb fm 34 4 9 Cross Section Along Shaft 1 4 10 14 g...

Page 35: ...ft Components See Graphic wc_gr001885 Ref Description Ref Description 1 Push rod 9 Stiffener 2 Carburetor 10 Plug 3 Air cleaner 11 Oil gauge 4 Tappet 12 Connecting rod 5 Camshaft 13 Spark plug 6 Gover...

Page 36: ...aks Check engine oil Check fuel level Check for loose hardware Clean debris from engine Change engine oil Clean air cleaner Check and clean spark plug Check and adjust valve clearances Remove carbon d...

Page 37: ...place the elements if they are damaged 5 2 2 Main paper filter element b Replace the main paper filter element if it appears heavily soiled 5 2 3 Prefilter c Clean the prefilter with low pressure comp...

Page 38: ...ly 5 3 2 Remove fuel line from fuel flow valve a 5 3 3 Unscrew fuel filter assembly b from tank 5 3 4 Clean filter with parts cleaning solvent 5 3 5 Inspect gasket c and filter for damage and replace...

Page 39: ...k 5 4 2 Start the engine and run it until remaining fuel is used 5 4 3 Remove the spark plug Pour approximately 30 ml 1 oz of clean SAE 10W30 engine oil into the cylinder through the spark plug openin...

Page 40: ...ent information refer to the Parts Book originally supplied with the machine If the original Parts Book has been lost a replacement may be ordered from Wacker Corporation When ordering a replacement P...

Page 41: ...ove the M8 x 16 bolt and washer d securing the guard to the engine 7 1 6 Remove the M8 bolt and washer e securing the guard to the rammer crankcase 7 1 7 Remove the six M8 bolts f securing the lower g...

Page 42: ...Disassembly Procedures WM 90 Repair wc_tx000389gb fm 42 d e j f wc_gr001954 b l a c k wc_gr003661...

Page 43: ...nmental protection place plastic sheeting and a container under the machine to collect the liquid which drains off Dispose of this liquid properly 7 2 1 Remove the drain plug a and gasket b 7 2 2 Remo...

Page 44: ...fm 44 7 3 Removing Recoil Starter and Blower Housing See Graphic wc_gr003650 7 3 1 Remove the bolts a and remove the recoil starter b from the housing 7 3 2 Remove the flange bolts f cap screw g and...

Page 45: ...bly Procedures wc_tx000389gb fm 45 7 4 Removing Muffler See Graphic wc_gr001888 7 4 1 Remove the flange nuts a 7 4 2 Remove the flange bolts b 7 4 3 Remove the bolts and washers c and remove the muffl...

Page 46: ...e the governor lever c 7 5 3 Remove the governor rod d and the rod spring e and if necessary bushing f 7 5 4 Remove the carburetor flange g the gaskets h the carburetor i 7 5 5 Remove the bolts j secu...

Page 47: ...e the ignition coil c 7 6 3 Remove the M12 nut and washer d four M6 bolts e and remove the starter pulley f and flywheel g If necessary break the nut loose by tapping the handle of the wrench with a h...

Page 48: ...7 1 Remove the four M6 x 60 bolts a and remove the rocker cover b and gasket c 7 7 2 Remove the breather d gaskets e and spacer f 7 7 3 Remove the two M8 x 55 bolts g and the two M8 bolts h remove th...

Page 49: ...fm 49 7 8 Removing Bearing Cover See Graphic wc_gr001893 7 8 1 Remove the nine M6 x 30 bolts and washers a and remove the main bearing cover b Note If necessary use a rubber mallet c and tap the cover...

Page 50: ...es WM 90 Repair wc_tx000389gb fm 50 7 9 Removing Camshaft and Tappets See Graphic wc_gr001894 7 9 1 Lay crankcase on the flywheel side and push the tappets a into the crankcase and remove the camshaft...

Page 51: ...r push out connecting rod d and piston assembly through top of cylinder Note Scrape off all carbon deposits that might interfere with removal of piston from upper end of cylinder 7 10 3 Remove the cli...

Page 52: ...Procedures WM 90 Repair wc_tx000389gb fm 52 7 11 Removing Crankshaft See Graphic wc_gr001896 7 11 1 To remove the crankshaft a tap lightly on flywheel end of the crankshaft with a rubber mallet b a b...

Page 53: ...e procedure is the same for removing each valve 7 12 1 Remove pivot bolt a rocker arm b and nut c 7 12 1 Press down the spring retainer d take out the collet e and then remove spring retainer and valv...

Page 54: ...o the lip Replace them if damaged Apply oil to lip before re assembling Replace all gaskets with new ones Replace keys pins bolts and nuts with new ones if necessary Tighten nuts and bolts to the spec...

Page 55: ...he piston Note When installing the piston rings make sure not to twist the rings too much as they may become damaged 8 3 1 Install the three piece oil ring c first When installing the oil ring install...

Page 56: ...res WM 90 Repair wc_tx000389gb fm 56 8 4 Reassembling Piston and Connecting Rod See Graphic wc_gr001901 8 4 1 Install the piston a onto the connecting rod b using the piston pin c and two clips d d d...

Page 57: ...he piston rings in and lower the piston into the cylinder Note If you do not have a ring guide hold the piston rings in with your fingers while tapping lightly on the piston head with a block of wood...

Page 58: ...fully to avoid damage during camshaft b installation 8 6 2 Remove spacer c to allow viewing of timing mark 8 6 3 Lubricate the bearing surfaces of camshaft Align the timing marks d on the camshaft wi...

Page 59: ...A Distance from main bearing cover mating surface a to the inner race of the ball bearing b 8 7 2 Measure the depth B Distance from the crankcase mating surface c to the crankshaft gear d B A side cle...

Page 60: ...with engine oil 8 8 2 Coat the mating surfaces of the main bearing cover a and crankcase b with Loctite 515 Gasket Eliminator or equivalent 8 8 3 Using nine M6 x 30 bolts and washers c secure the mai...

Page 61: ...ld be replaced when valve stem clearance exceeds specifications See Clearance Data and Limits Table 8 9 4 Draw valve guides out and press new guides in See Clearance Data and Limits Table 8 9 5 After...

Page 62: ...appens removal of the main bearing cover will be necessary to remove them 8 10 2 Place the gasket b on the crankcase Position the intake valve c and the exhaust valve d into the cylinder head e Using...

Page 63: ...enter of the compression stroke by matching the alignment mark on the flywheel a with the alignment mark on the crankcase b 8 11 3 Loosen the nut c under the rocker arm Position a feeler gauge e as sh...

Page 64: ...r is removed 8 12 1 Using four M6 bolts a secure the rocker cover b and gasket c to the cylinder head 8 12 2 Remove any carbon deposits from the spark plug and inspect the electrode for damage Replace...

Page 65: ...ywheel center hole 8 13 2 Install the flywheel M12 nut and washer to the crankshaft Hold the flywheel using a strap wrench and torque the nut to 44 2 49 1 Nm 32 5 36 2 ft lbs 8 14 Installing Ignition...

Page 66: ...sher o pivot bolt n spacer r and return spring q 8 15 4 Attach the governor spring c to proper holes as marked during disassembly of governor lever and speed control lever 8 15 5 Using bolts j install...

Page 67: ...g c and carburetor throttle valve is fully open 8 16 3 Turn the governor shaft d clockwise all the way using a screw driver and tighten the lock bolt to secure the lever on the shaft 8 16 4 Loosen the...

Page 68: ...fm 68 8 18 Installing Blower Housing and Recoil Starter See Graphic wc_gr003650 8 18 1 Install the blower housing h using the flange bolts f and cap screw g 8 18 2 Install the recoil starter b to the...

Page 69: ...wire from the low oil unit l if equipped to the engine 8 19 3 Using six M8 bolts f mount the guards to the engine Secure upper guard to engine using M8 x 16 bolt d and to rammer crankcase using M8 bo...

Page 70: ...Reassembly Procedures WM 90 Repair wc_tx000389gb fm 70 d e j f wc_gr001954 b l a c k wc_gr003661...

Page 71: ...urfaces and running clearances between the various parts can only be established by operating the engine under reduced speed and loads for a short period of time Run in the engine according to the sch...

Page 72: ...volution when the flywheel reaches the ignition point the low speed ignition timing control circuit operates to run the base current I3 to turn the signal transistor A ON allowing the current I1 to by...

Page 73: ...tion 1 Low speed ignition timing circuit 9 Spark plug 2 Signal transistor A 10 Ignition timing BTDC 3 Automatic advancing control circuit 11 Engine revolution rpm 4 Signal transistor B 12 Step advanci...

Page 74: ...ightly to release compression The release lever has a flyweight c on one end and a crescent cam d on the other When the engine is cranked the crescent cam projects above the cam profile and lifts up t...

Page 75: ...en submitted to a positive pressure 6 Inlet screen The inlet screen filters the fuel that is drawn from the fuel tank to the carburetor 7 Inlet needle valve The inlet needle valve controls the fuel th...

Page 76: ...fuel when the engine is at idling speeds and when the throt tle is at low speed position 17 High speed needle The high speed needle has the function of controlling the fuel when the engine is operatin...

Page 77: ...WM 90 Repair Sub Systems wc_tx000390gb fm 77 9 12 11 7 17 20 6 4 5 2 19 18 3 1 8 15 14 16 13 10 wc_gr001919...

Page 78: ...d remove the screw and the pump cover 13 9 6 2 Remove the pump gasket 12 and the diaphragm 11 9 6 3 Place the carburetor with the metering side up and remove the metering cover screws 8 9 6 4 Remove t...

Page 79: ...heck the throttle shaft 19 and the choke shaft 20 for smooth operation 9 7 6 Check the inlet screen 1 for dirt If the screen is dirty wash it and blow it out with compressed air 9 7 7 Check the inlet...

Page 80: ...ust screw 15 so that the engine is running at a speed slightly lower than the speed at which the clutch engages High Speed Adjustment 9 9 2 Set the throttle valve 16 to the fully open position and che...

Page 81: ...down firmly with both thumbs taking care to not allow it to spring back Note The following procedure requires the help of an assistant 10 1 4 Remove the knot from the reel untie the knot and pull the...

Page 82: ...1831 Remove the reel 10 1 8 Hold down the reel f gently to keep it from escaping from its case and rotate it slowly back and forth by quarter turns until it moves smoothly 10 1 9 Lift the reel up slig...

Page 83: ...ouches the rib of the bearing 10 1 13 Hold the reel in such a way that the inner end of the spring hooks onto the shaft hook c and then place the reel carefully back into the case See Graphic wc_gr001...

Page 84: ...ss the rope through the rope guide and the rope hole of the reel and pull through approximately 20 cm 7 3 4 in out of the reel 10 1 20 Tie a knot in the end of the rope 10 1 21 Put the rope into the r...

Page 85: ...the reel the spring may be over stressed To fix this pull out the starter rope approximately 30 cm 11 3 4 and controlling the rotation of the reel with your thumb allow the starter rope to rewind abou...

Page 86: ...numbers 0009386 rev 112 and higher 0009340 rev 112 and higher 0620051 rev 108 and higher Ref Description Ref Description 1 Starter assembly 8 Spring 2 Rope 9 Ratchet wheel 3 Handle 10 Cover 4 Wear pla...

Page 87: ...ted or twisted Check that the starter return spring ends are bent 180 a The starter return spring may be difficult to seat in the slots on the starter housing and the rope reel pulley if the return sp...

Page 88: ...ecting between the spring windings avoid using grease to lubricate the tarter return spring or the inside of the reel where the spring seats Use a light lubricating oil such as WD40 instead 10 6 3 Ins...

Page 89: ...assembly from the flywheel housing 10 7 2 Lift the rope through the notch a in the drum Pull out as much of the rope as possible Hold the rope and let the spring pull the drum around clockwise until a...

Page 90: ...Recoil Starter WM 90 Repair wc_tx000627gb fm 90 wc_gr002882 a d e b c...

Page 91: ...ists the dimension of the part as new from the factory The Limit column lists the maximum allowance If the measurement exceeds the Limit dimension listed replace or repair the part Item Standard mm in...

Page 92: ...Oversize 0 50 51 47 51 49 2 0264 2 0272 51 38 2 0228 Ring groove side clearance Top 0 035 0 080 0 0014 0 0031 0 15 0 006 2nd 0 035 0 080 0 0014 0 0031 0 15 0 006 Oil Ring 0 010 0 065 0 0004 0 0026 0 1...

Page 93: ...g 0 05 0 25 0 002 0 010 1 5 0 0591 Cylinder Inner diameter Standard STD 51 000 51 019 2 008 2 009 To be rebored when the differ ence between max and min diameter reaches 0 1 0 004 First reboring 51 25...

Page 94: ...7874 0 7879 20 1 0 7913 Clearance between large end and crank pin 0 037 0 063 0 0015 0 0025 0 2 0 008 Small end inner diameter 11 010 11 021 0 4335 0 4339 11 08 0 4362 Clearance bewteen small end and...

Page 95: ...1 0 0 04 Crankshaft Crank pin outer diameter 19 950 19 963 0 7854 0 7859 19 85 0 7815 Journal outer diameter D1 and D2 19 988 19 997 0 7869 0 7873 Camshaft Cam peak height intake and exhaust 18 3 18 5...

Page 96: ...stem outer diameter Intake 5 440 5 455 0 2142 0 2148 5 35 0 2106 Exhaust 5 426 5 444 0 2136 0 2143 5 35 0 2106 Clearance between valve stem and valve guide Intake 0 045 0 078 0 0018 0 0031 0 3 0 0118...

Page 97: ...134 0 3140 Guide inside diameter 8 00 8 015 0 3150 0 3140 Tappet guide clearance 0 025 0 055 0 0010 0 0022 Valve seat angle intake and exhaust Valve cutter angle a Valve contact width b a 90 b 0 8 1 1...

Page 98: ...Clearance Data and Limits Table WM 90 Repair wc_tx000391gb fm 98 Valve spring free length 26 7 1 05 Item Standard mm in Limit mm in wc_gr001947...

Page 99: ...her factors as well that will make engine starting difficult such as a heavy load on the engine when attempting to start or heavy back pressure due to a long exhaust pipe 12 2 Troubleshooting Procedur...

Page 100: ...rnal engine is completely dry because of a long period of storage 12 2 3 2 Loose or broken spark plug This causes a hissing noise made by the fuel air mixture running out of the cylinder in compressio...

Page 101: ...icted 12 2 6 5 Cooling air path misdirected causing loss of cooling efficiency 12 2 6 6 Cylinder head cooling fins clogged with dirt 12 2 6 7 Engine being operated in an enclosed space without suffici...

Page 102: ...Troubleshooting WM 90 Repair wc_tx000393gb fm 102 Notes...

Page 103: ...5 ml 17380 50 ml Loctite 271 277 Hernon 427 Omnifit 1550 220M Red High strength for all threads up to 25 mm 1 Heat parts before disassembly Temp range 54 to 149 C 65 to 300 F 29312 5 ml 26685 10 ml 7...

Page 104: ...ts follow instructions on container The sealants listed are recommended for use on Wacker equipment TYPE Europe COLOR USAGE PART NO SIZE Loctite 496 Hernon 110 Omnifit Sicomet 7000 Clear Instant adhes...

Page 105: ...5 M4 2 9 26 4 1 36 4 9 43 7 9 32 3 M5 6 0 53 8 5 6 10 7 8 5 16 4 M6 10 7 14 10 17 13 10 5 M8 25 18 35 26 41 30 13 1 2 6 M10 49 36 69 51 83 61 17 11 16 8 M12 86 63 120 88 145 107 19 3 4 10 M14 135 99 1...

Page 106: ...8 2 5 22 3 5 31 4 7 42 9 11 32 9 64 No 10 3 6 32 5 1 45 6 8 60 3 8 5 32 1 4 8 1 6 12 9 16 12 7 16 3 32 5 16 18 13 26 19 33 24 13 1 2 1 4 3 8 31 23 45 33 58 43 9 16 5 16 7 16 50 37 71 52 94 69 16 5 8...

Page 107: ......

Page 108: ...02 0 Fax 49 0 89 3 54 02 3 90 Wacker Corporation P O Box 9007 Menomonee Falls WI 53052 9007 Tel 262 255 0500 Fax 262 255 0550 Tel 800 770 0957 Wacker Asia Pacific Operations Skyline Tower Suite 2303 2...

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