Yamaha MX800V Service Manual Download Page 120

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6-2

OUBLESH

TIN

ENGINE DOES NOT START

ELECTRIC STARTING SYSTEM

The starter motor fails to turn.

No.

Checking steps

Possible remedy

Check the battery.

• Clean the battery terminals.
• Recharge or replace the battery.

Check the starter motor operation.
(Refer to “CHECKING THE STARTER MOTOR OPERA-
TION” on page 5-8)

If the starter motor operates normally,
the starter motor is OK.

Check the starter motor.
(Refer to “ELECTRIC STARTING SYSTEM” on page 5-10)

Repair or replace the starter motor.

Check the main switch.

Replace the main switch.

Check the entire starting system’s wiring.
(Refer to “CIRCUIT DIAGRAM” on page 5-1)

Properly connect or repair the starting
system’s wiring.

The starting system circuit is OK.

—

Summary of Contents for MX800V

Page 1: ...SERVICE MANUAL MX800V MX825V 7UC F8197 E0 LIT 19616 02 50 2017 10 1 7UC F8197 E0_Hyoshi indd 1 2 2017 10 27 13 08 23 ...

Page 2: ...7UC F8197 E0_Hyoshi indd 3 4 2017 10 27 13 08 23 ...

Page 3: ...UAL 2017 by Yamaha Motor Corporation U S A 1st Edition October 2017 All rights reserved Any reprinting or unauthorized use without the written permission of Yamaha Motor Corporation U S A is expressly prohibited LIT 19616 02 50 ...

Page 4: ... the most satisfaction from their machine and to con form to federal environmental quality objectives Yamaha Motor Powered Products Co Ltd is continually striving to improve all of its models Modifi cations and significant changes in specifications or procedures will be forwarded to all authorized Yamaha dealers and will appear in future editions of this manual where applicable TIP This Service Ma...

Page 5: ...han the section title 2 To help identify parts and clarify procedure steps there are exploded diagrams at the start of each removal and disassembly section 3 Numbers are given in the order of the jobs in the exploded diagram A number indicates a disas sembly step 4 Symbols indicate parts to be lubricated or replaced 5 Refer to SYMBOLS A job instruction chart accompanies the exploded diagram provid...

Page 6: ...ant to every machine SYMBOL DEFINITION SYMBOL DEFINITION Filling fluid Lubricant Special tool Tightening torque Wear limit clearance Engine speed Electrical data Replace the part with a new one Lithium soap base grease Molybdenum disulfide grease Engine oil Silicone fluid Apply locking agent LOCTITE T R New LS M E S LT ...

Page 7: ...GENERAL INFORMATION PERIODIC CHECKS AND ADJUSTMENTS ENGINE FUEL ELECTRICAL TROUBLESHOOTING SPECIFICATIONS 1 2 3 4 5 6 7 8 9 10 INDEX ...

Page 8: ...LACING THE ENGINE OIL 2 6 FUEL LEAKAGE 2 8 FUEL FILTER 2 8 OIL COOLER 2 9 AIR FILTER ELEMENT 2 9 ADJUSTING THE VALVE CLEARANCE 2 9 CYLINDER HEADS DECARBONIZATION 2 13 ENGINE SPEED 2 14 ADJUSTING THE ENGINE SPEED 2 15 LOW ENGINE SPEED Replace the carburetor assembly 2 16 FITTINGS AND FASTENERS 2 17 ENGINE ENGINE INSPECTION 3 1 MEASURING THE COMPRESSION PRESSURE 3 1 AIR FILTER 3 3 MUFFLER For models...

Page 9: ...HAFT ASSEMBLY 3 40 ASSEMBLING THE FLYWEIGHT SHAFT ASSEMBLY 3 41 INSTALLING THE FLYWEIGHT SHAFT ASSEMBLY AND GOVERNOR FORK 3 41 REMOVING THE CAMSHAFT AND VALVE LIFTERS 3 42 CHECKING THE CAMSHAFT 3 42 CHECKING THE VALVE LIFTERS 3 43 CHECKING THE REED VALVE 3 44 INSTALLING THE VALVE LIFTERS AND CAMSHAFT 3 44 INSTALLING THE COVER 1 3 44 INSTALLING THE COVER 2 3 45 CHECKING THE CRANKCASE COVER 1 3 45 I...

Page 10: ...2 CHECKING THE BRUSH 5 13 CHECKING THE STARTER RELAY 5 13 ASSEMBLING THE STARTER MOTOR 5 13 TROUBLESHOOTING ENGINE DOES NOT START 6 1 IGNITION SYSTEM 6 1 ELECTRIC STARTING SYSTEM 6 2 OTHER TROUBLES 6 3 ENGINE STARTS BUT STALLS 6 3 ENGINE SPEED DOES NOT INCREASE 6 4 ENGINE SPEED IS UNEVEN 6 5 THE BATTERY IS NOT CHARGED 6 6 GOVERNOR OPERATION 6 7 OIL PRESSURE SYSTEM 6 8 SPECIFICATIONS GENERAL SPECIF...

Page 11: ...the position of the multi purpose engine as shown in the illus tration TIP The first four digits identify the model and the remaining digits indicates the production number Designs and specifications are subject to change without notice STARTING SERIAL NUMBER 1 Model Code Starting serial num ber MX800VH7J6 7U3J00 7U3J 1000101 MX825VH7J6 7UCJ00 7UCJ 1000101 ...

Page 12: ...ONS 1 2 1 2 3 4 5 6 7 8 9 10 GENERAL INFORMATION DIMENSIONS TOP MOUNTING BASE 1 UNC Unified coarse thread Unit in 2 PCD Pitch Circle Diameter mm in mm in 499 2 19 65 157 1 6 19 35 35 45 45 PCD 254 4 3 8 16UNC ...

Page 13: ...1 3 1 2 3 4 5 6 7 8 9 10 GENERAL INFORMATION DIMENSIONS REAR REAR For models equipped with a muffler mm in mm in 451 2 17 76 235 1 9 26 451 2 17 76 445 4 17 54 235 1 9 26 ...

Page 14: ...DIMENSIONS 1 4 1 2 3 4 5 6 7 8 9 10 GENERAL INFORMATION RIGHT SIDE RIGHT SIDE For models equipped with a muffler mm in mm in 416 2 16 39 108 8 4 28 639 25 16 416 2 16 39 116 7 4 59 108 8 4 28 639 25 16 ...

Page 15: ...g the engine always keep the engine and yourself away from fire NOTES ON SERVICE Correct tools Be sure to use the correct special tool for the job to guard against damage Oil grease and seals Be sure to use genuine Yamaha oils grease and sealers or the equivalents Expendable parts Always replace the gaskets O rings cotter pins and cir clips with new parts when servicing engine ...

Page 16: ...sassembly Contact surfaces of moving parts should be oiled when reassembled Make sure that the parts move smoothly after each sec tion of the machine is assembled ALL REPLACEMENT PARTS We recommend the use of genuine Yamaha parts for all replacements Use oil and or grease recommended by Yamaha for assembly and adjustment GASKETS OIL SEALS AND O RINGS 1 All gaskets seals and O rings should be repla...

Page 17: ...ium base grease to the seal lip s Oil the bearings liberally when installing BASIC SERVICE INFORMATION ELECTRICAL SYSTEM Checking the electrical system TIP Before checking the electrical system make sure that the battery voltage is at least 12 V 1 2 Do not use compressed air to spin the bearings dry This causes damage to the bearing surfaces NOTICE a Never insert the tester probes into the coupler...

Page 18: ...r blower Rust stains Connect and disconnect several times When disconnecting a coupler release the coupler lock hold both sections of the coupler securely and then disconnect the coupler There are many types of coupler locks therefore be sure to check the type of coupler lock before discon necting the coupler NOTICE When disconnecting a connector do not pull the leads Hold both sections of the con...

Page 19: ...ontinuity with the digital circuit tester TIP If there is no continuity clean the terminals When checking the wire harness perform steps 1 to 3 As a quick remedy use a contact revitalizer available at most part stores Model 88 Multimeter with tachometer YU A1927 For waterproof couplers never insert the tester leads directly into the coupler When performing any checks using a waterproof coupler use...

Page 20: ...iques Valve spring compressor 90890 01253 Ignition checker 90890 06754 Digital tachometer YU 39951 B 90890 06760 Feeler gauge set YU 26900 9 Oil filter wrench YM 01469 Engine compression tes ter YU 33223 Primary clutch holder YU 01235 Rotor holding tool 90890 01235 Heavy duty puller YU 33270 B Cylinder gauge Commercially obtainable Piston ring compressor YM 08037 Dial indicator gauge YU A8428 Pres...

Page 21: ...missions control These controls not only function to ensure air filter but are also vital to proper engine operation and maximum performance PERIODIC MAINTENANCE LUBRICATION INTERVALS 1 For models equipped with a Yamaha muffler 2 Items marked with an asterisk require special tools data and technical skills have a Yamaha dealer perform the service Daily 50 hrs 100 hrs 200 hrs 250 hrs 500 hrs 1000 h...

Page 22: ...uge set Out of specification Regap If necessary clean the spark plugs with a spark plug cleaner TIP Before installing the spark plugs clean the gasket surface and plug surface Check and adjust the areas around the cylinder head after the engine has cooled down completely WARNING 1 Before removing the spark plugs use compressed air to clean the cylinder head covers to prevent dirt from falling into...

Page 23: ...MUFFLER For models equipped with a muffler 1 Remove Spark arrester screw 1 2 Remove Spark arrester 1 TIP Use a flathead screw driver to pry the spark arrester out from the muffler a b Spark plug 20 N m 2 0 kgf m 15 lb ft T R The engine and muffler will be very hot after the engine has been run Avoid touching the engine and muffler while they are still hot with any part of your body or clothing dur...

Page 24: ...r 6 Install Muffler Refer to MUFFLER For models equipped with a muffler on page 3 4 Spark arrester Spark arrester screw TIP Align the spark arrester lump a with the hole b in the muffler pipe ENGINE OIL LEAKAGE 1 Place the multi purpose engine on a level surface Do not use a wire brush to clean otherwise the noise damping material may come out and the damping effect may be reduced NOTICE When clea...

Page 25: ...Check that engine oil is at the specified level a Place the multi purpose engine on a level surface b Warm up the engine for several minutes c Stop the engine d Remove the oil filler cap e Wipe the engine oil dipstick 1 clean insert it back into the oil filler hole without screwing it in and then remove it again to check the oil level Add oil if necessary TIP The engine oil should be between the m...

Page 26: ...rm up the engine for several minutes and then stop the engine Place the oil pan under the engine 2 Remove Oil filler cap Oil drain bolt 1 Oil drain bolt gasket 2 3 Drain Engine oil 4 If the oil filter is also to be replaced perform the fol lowing procedure a Remove the oil filter 1 with an oil filter wrench 2 Avoid draining the engine oil immediately after stop ping the engine The oil is hot and s...

Page 27: ... the oil filler hole 1 in the crankcase 7 Check Engine oil level Refer to ENGINE OIL LEVEL on page 2 5 Make sure the O ring 3 is positioned correctly in the groove of the oil filter NOTICE Oil filter 14 N m 1 4 kgf m 10 lb ft T R 2 1 Oil drain bolt 27 N m 2 7 kgf m 20 lb ft New T R 1 0 10 30 50 70 90 110130 F 20 10 0 10 20 30 40 50 C SAE 10W 40 SAE 10W 30 Recommended engine oil YAMALUBE SAE 10W 30...

Page 28: ...rburetor assembly FUEL FILTER 1 Remove Fuel filter 2 Check Fuel filter Damage Replace Dirt clog Clean TIP Clean the fuel filter with clean gasoline and then dry it thoroughly Replace fuel hose every four years NOTICE Do not smoke and keep away from open flames sparks or any other source of fire when handling or in the vicinity of fuel WARNING ...

Page 29: ...age dirty Replace 3 Install Inner element Air filter element Air filter case cover Dust cap ADJUSTING THE VALVE CLEARANCE The following procedure applies to all of the valves 1 Remove Spark plug cap 1 Spark plug 2 Be sure not to run the engine without air filter element Otherwise this can result in excessive piston and or cylinder wear NOTICE 1 2 3 Before removing the spark plug use compressed air...

Page 30: ...9 4 Turn the crankshaft clockwise and then set the piston at TDC top dead center on the compression stroke TIP Check the piston position by inserting a screw driver into the spark plug hole 5 Measure Valve clearance Between the rocker arm and adjusting pad Out of specification Adjust to original set value at every 1000 hr TIP Valve clearance must be measured when the engine has cooled down enough ...

Page 31: ... adjusting pad 3 so that they can be installed in the correct place b Calculate the difference between the specified valve clearance and the measured valve clearance Example Specified valve clearance 0 07 0 13 mm 0 003 0 005 in Measured valve clearance 0 18 mm 0 007 in 0 18 mm 0 007 in 0 13 mm 0 005 in 0 05 mm 0 002 in Valve clearance cold Normal ENG operation range between 1000 hr periodic mainte...

Page 32: ...ting pad number Example 1 80 mm 0 071 in 0 05 mm 0 002 in 1 85 mm 0 073 in The adjusting pad number is 185 e Round off the adjusting pad number according to the following table and then select the suitable adjusting pad TIP Refer to the following table for the available adjusting pads Example Adjusting pad number 188 Rounded value 200 New adjusting pad number 200 f Install the new adjusting pad 4 ...

Page 33: ... adjustment steps until the specified clearance is obtained 7 Install Cylinder head cover gasket Cylinder head cover Cylinder head cover bolts Spark plug Spark plug cap CYLINDER HEADS DECARBONIZATION 1 Remove Cylinder heads Refer to CYLINDER HEAD COVERS CYLINDER HEADS on page 3 19 2 Eliminate Carbon deposits Refer to CHECKING THE CYLINDER HEADS on page 3 23 3 Install Cylinder heads Refer to INSTAL...

Page 34: ...ad Out of specification Adjust a Move the throttle lever 1 to the high engine speed position a b Check the high engine speed 4 Measure Low engine speed with no load Out of specification Adjust a Move the throttle lever 1 to the low engine speed position a 1 Digital tachometer YU 39951 B 90890 06760 High engine speed with no load 3550 3650 r min a a 1 Low engine speed with no load 1650 1750 r min 1...

Page 35: ...ter 1 3 Adjust High engine speed a Move the throttle lever 1 to the high engine speed position a b Turn the throttle stop screw 2 in direction b or c until the high engine speed is obtained 4 Adjust Low engine speed 1 Digital tachometer YU 39951 B 90890 06760 b c 1 2 a Direction b High engine speed is increased Direction c High engine speed is decreased High engine speed with no load 3550 3650 r m...

Page 36: ... assembly follow the procedure below Adjust low engine speed with throttle stop screw 1 in direction a or b 1 Turn the throttle stop screw 1 carburetor assembly in direction a or b until the low engine speed is obtained 1 a a b c 2 Direction b Low engine speed is decreased Direction c Low engine speed is increased Low engine speed with no load 1650 1750 r min a b 1 Direction a Low engine speed is ...

Page 37: ... 4 5 6 7 8 9 10 PERIODIC CHECKS AND ADJUSTMENTS PERIODIC MAINTENANCE FITTINGS AND FASTENERS 1 Check All fittings and fasteners Looseness Tighten Rough movement Replace the defective part s Damage pitting Replace ...

Page 38: ...2 18 1 2 3 4 5 6 7 8 9 10 PERIODIC CHECKS AND ADJUSTMENTS PERIODIC MAINTENANCE MEMO ...

Page 39: ...ension 2 4 Measure Compression pressure Open the throttle and crank the engine until the needle stop rising on the engine compression tes ter Out of specification Refer to steps a and b Before removing the spark plug use compressed air to clean the cylinder head cover to prevent dirt from falling into the engine NOTICE 1 2 Engine compression tester YU 33223 Standard compression pressure 490 640 kP...

Page 40: ...ssion pressure is above the maximum specification check the cylinder head valve sur faces and piston crown for carbon deposits Carbon deposits Eliminate 5 Install Spark plug Spark plug cap Reading Diagnosis Higher than without oil Worn cylinder piston and piston ring s Same as without oil Defective piston piston ring s valve s and cylinder head gasket Improper valve timing and valve clearance Spar...

Page 41: ... in the order listed 1 Dust cap 1 2 Air filter case cover 1 3 Air filter element 1 4 Inner element 1 5 Air filter cover 1 1 6 Air filter case stay 1 7 Air filter case 1 8 Joint 2 1 1 2 3 4 5 6 6 7 8 10 N m 1 0 kgf m 7 4 lb ft 1 8 N m 0 18 kgf m 1 3 lb ft 1 8 N m 0 18 kgf m 1 3 lb ft 7 N m 0 7 kgf m 5 2 lb ft 7 N m 0 7 kgf m 5 2 lb ft ...

Page 42: ...ler MUFFLER For models equipped with a muffler Order Job Parts to remove Q ty Remarks Removing the muffler Remove the parts in the order listed 1 Muffler 1 2 Spark arrester 1 3 Gasket 2 1 2 3 3 5 N m 0 35 kgf m 2 6 lb ft 20 N m 2 0 kgf m 15 lb ft 20 N m 2 0 kgf m 15 lb ft ...

Page 43: ...ove the parts in the order listed Engine oil Drain Refer to REPLACING THE ENGINE OIL on page 2 6 1 Oil cooler 1 2 Oil hose 1 1 3 Oil hose 2 1 4 Oil filter 1 5 Adapter union bolt 1 6 Adapter 1 7 Oil seal 1 17 N m 1 7 kgf m 13 lb ft 14 N m 1 4 kgf m 10 lb ft 9 N m 0 9 kgf m 6 6 lb ft 62 N m 6 2 kgf m 46 lb ft 1 2 3 4 5 6 7 ...

Page 44: ...own in the illustration 2 Remove Oil hose 1 Oil hose 2 Oil cooler CHECKING THE OIL COOLER 1 Check Oil cooler 1 Oil hose 1 2 Oil hose 2 3 Adapter 4 Damage Replace Dirt clog Clean INSTALLING THE OIL COOLER 1 Clean Mating surfaces of the adapter and the crankcase cover 2 with a cloth dampened with lacquer thinner 2 Install Oil seal 1 Adapter 2 Adapter union bolt 3 1 2 a A Hose clamp pliers 1 2 3 4 1 ...

Page 45: ...er 2 3 Install Oil filter Oil hose 2 Oil hose 1 Hose clamp Clic R 1 TIP Install the hose clamp using the hose clamp pliers 2 When installing the hose clamp make sure that the thin tip a of the hose clamp pliers is directed as shown in the illustration 4 Install Oil cooler Oil cooler bolts a b 1 2 a A Hose clamp pliers New Oil cooler bolt 9 N m 0 9 kgf m 6 6 lb ft T R ...

Page 46: ...arts to remove Q ty Remarks Removing the rectifier regulator Remove the parts in the order listed 1 Earth terminal 1 2 Engine hunger 1 For maintenance 3 Rectifier regulator lead connector 2 Disconnect 4 Rectifier regulator 1 20 N m 2 0 kgf m 15 lb ft 7 N m 0 7 kgf m 5 2 lb ft 1 3 4 2 ...

Page 47: ...fer to RECTIFIER REGULATOR on page 3 8 Fuel pump Refer to FUEL PUMP on page 4 1 Oil cooler Refer to OIL COOLER on page 3 5 1 Oil filler cap 1 2 Oil filler pipe 1 3 O ring 1 4 Fan case cover 1 5 Grass screen 1 6 Fan case 1 7 Fan 1 10 N m 1 0 kgf m 7 4 lb ft 10 N m 1 0 kgf m 7 4 lb ft 10 N m 1 0 kgf m 7 4 lb ft 7 N m 0 7 kgf m 5 2 lb ft 7 N m 0 7 kgf m 5 2 lb ft 7 N m 0 7 kgf m 5 2 lb ft 1 2 3 4 5 6...

Page 48: ...gulator Refer to RECTIFIER REGULATOR on page 3 8 3 Remove Fuel pump Refer to FUEL PUMP on page 4 1 4 Remove Oil cooler Refer to OIL COOLER on page 3 5 5 Remove Oil filler cap Oil filler pipe 6 Remove Fan case cover 1 Grass screen 2 Fan case 3 Fan 4 1 2 3 4 Because there is a risk of damage remove the grass screen 2 and fan case 3 in this order NOTICE ...

Page 49: ...Clean INSTALLING THE CASE AND FAN 1 Install Fan 1 Fan bolts Fan case 2 Fan case bolts Grass screen 3 Grass screen bolts Fan case cover 4 Fan case cover bolts 1 2 3 4 4 3 2 1 Fan bolt 10 N m 1 0 kgf m 7 4 lb ft Fan case bolt 7 N m 0 7 kgf m 5 2 lb ft Grass screen bolt 10 N m 1 0 kgf m 7 4 lb ft Fan case cover bolt 7 N m 0 7 kgf m 5 2 lb ft T R T R T R T R ...

Page 50: ...SE AND FAN TIP Insert the tab a of the fan case cover 4 into the hole b of the fan case 2 first and then install 2 Install Oil filler pipe Oil filler pipe bolt Oil filler cap 2 4 a b a b Oil filler pipe bolt 7 N m 0 7 kgf m 5 2 lb ft T R ...

Page 51: ... AIR FILTER on page 3 3 Rectifier regulator Refer to RECTIFIER REGULATOR on page 3 8 Fuel pump Refer to FUEL PUMP on page 4 1 Oil cooler Refer to OIL COOLER on page 3 5 Fan case Refer to CASE AND FAN on page 3 9 1 TCI unit 1 lead connector 1 Disconnect 2 TCI unit 2 lead connector 1 Disconnect 3 TCI unit 1 1 4 TCI unit 2 1 5 Spark plug 2 20 N m 2 0 kgf m 15 lb ft 5 20 N m 2 0 kgf m 15 lb ft 5 4 3 1...

Page 52: ...s in the order listed Air filter case Refer to AIR FILTER on page 3 3 Rectifier regulator Refer to RECTIFIER REGULATOR on page 3 8 Fuel pump Refer to FUEL PUMP on page 4 1 Oil cooler Refer to OIL COOLER on page 3 5 Fan case Refer to CASE AND FAN on page 3 9 TCI units Refer to TCI UNITS on page 3 13 1 Flywheel 1 2 Woodruff key 1 3 Stator coil assembly 1 180 N m 18 kgf m 133 lb ft 7 N m 0 7 kgf m 5 ...

Page 53: ... Refer to RECTIFIER REGULATOR on page 3 8 3 Remove Fuel pump Refer to FUEL PUMP on page 4 1 4 Remove Oil cooler Refer to OIL COOLER on page 3 5 5 Remove Fan case cover Grass screen Fan case Fan Refer to CASE AND FAN on page 3 9 6 Remove TCI units 1 7 Remove Flywheel nut 1 Washer 2 TIP Attach the primary clutch holder 3 to hold the flywheel 1 1 3 2 Primary clutch holder YU 01235 Rotor holding tool ...

Page 54: ...he flywheel If necessary one bolt may be backed out slightly to level the tool body 9 Remove Stator coil assembly CHECKING THE FLYWHEEL AND STATOR COIL ASSEMBLY 1 Check Flywheel 1 Stator coil assembly 2 Damage Replace INSTALLING THE FLYWHEEL AND STATOR COIL ASSEMBLY 1 Install Stator coil assembly Stator coil assembly bolts 2 Install Woodruff key Flywheel 1 2 Heavy duty puller YU 33270 B 1 2 Stator...

Page 55: ...NG THE TCI UNITS on page 3 18 5 Install Fan Fan case Grass screen Fan case cover Refer to CASE AND FAN on page 3 9 6 Install Fuel pump Refer to FUEL PUMP on page 4 1 7 Install Rectifier regulator Refer to RECTIFIER REGULATOR on page 3 8 8 Install Air filter case Refer to AIR FILTER on page 3 3 1 3 2 Flywheel nut 180 N m 18 kgf m 133 lb ft Primary clutch holder YU 01235 Rotor holding tool 90890 012...

Page 56: ...e TCI unit air gap Out of specification Adjust 3 Adjust TCI unit air gap a Loosen the TCI unit bolts 1 b Adjust the TCI unit air gap c Tighten the TCI unit bolts 1 TCI unit bolt 10 N m 1 0 kgf m 7 4 lb ft T R Feeler gauge set YU 26900 9 TCI unit air gap 0 4 0 6 mm 0 0157 0 0236 in 1 Feeler gauge set YU 26900 9 TCI unit air gap 0 4 0 6 mm 0 0157 0 0236 in TCI unit bolt 10 N m 1 0 kgf m 7 4 lb ft T ...

Page 57: ...age 3 8 Fuel pump Refer to FUEL PUMP on page 4 1 Oil cooler Refer to OIL COOLER on page 3 5 Fan case Refer to CASE AND FAN on page 3 9 Flywheel and stator coil assembly Refer to FLYWHEEL AND STATOR COIL ASSEMBLY on page 3 14 Carburetor assembly Refer to CARBURETOR ASSEMBLY on page 4 3 Intake manifold Refer to INTAKE MANIFOLD on page 4 7 Starter motor assembly Refer to REMOVING THE STARTER MOTOR on...

Page 58: ...et 1 4 Rocker arm shaft 1 Intake 5 Rocker arm shaft 1 Exhaust 6 Rocker arm 1 Intake 7 Rocker arm 1 Exhaust 8 Adjusting pad 3 9 Push rod 2 10 Cylinder head assembly 1 1 11 Cylinder head gasket 1 12 Dowel pin 2 1 2 3 4 5 6 7 8 8 9 10 11 12 12 11 N m 1 1 kgf m 8 1 lb ft 4 0 N m 0 40 kgf m 3 0 lb ft 7 N m 0 7 kgf m 5 2 lb ft 50 N m 5 0 kgf m 37 lb ft 12 N m 1 2 kgf m 8 9 lb ft 1st 2nd ...

Page 59: ...Refer to FUEL PUMP on page 4 1 Oil cooler Refer to OIL COOLER on page 3 5 Fan case Refer to CASE AND FAN on page 3 9 Flywheel and stator coil assembly Refer to FLYWHEEL AND STATOR COIL ASSEMBLY on page 3 14 Carburetor assembly Refer to CARBURETOR ASSEMBLY on page 4 3 Intake manifold Refer to INTAKE MANIFOLD on page 4 7 Starter motor assembly Refer to REMOVING THE STARTER MOTOR on page 5 10 11 N m ...

Page 60: ...head cover gasket 1 5 Rocker arm shaft 1 Intake 6 Rocker arm shaft 1 Exhaust 7 Rocker arm 1 Intake 8 Rocker arm 1 Exhaust 9 Adjusting pad 3 10 Push rod 2 11 Cylinder head assembly 2 1 12 Cylinder head gasket 1 13 Dowel pin 2 11 N m 1 1 kgf m 8 1 lb ft 7 N m 0 7 kgf m 5 2 lb ft 2 3 4 5 6 7 8 9 9 11 10 12 13 13 4 0 N m 0 40 kgf m 3 0 lb ft 1 50 N m 5 0 kgf m 37 lb ft 12 N m 1 2 kgf m 8 9 lb ft 1st 2...

Page 61: ...E PUSH RODS The following procedure applies to all of the push rods 1 Check Push rod runout Out of specifications Replace REMOVING THE CYLINDER HEADS The following procedure applies to all of the cylinder heads 1 Remove Cylinder head TIP Set the piston at TDC top dead center on the compres sion stroke Refer to ADJUSTING THE VALVE CLEARANCE on page 2 9 CHECKING THE CYLINDER HEADS The following proc...

Page 62: ...t surface of the cylin der head at six points using the straight edge and feeler gauge set Out of specifications Resurface or replace INSTALLING THE CYLINDER HEAD ASSEMBLY 1 Install Cylinder head assembly 1 Cylinder head bolts 1 to 5 TIP Tighten the bolts to the specified torque in two steps and in order from 1 to 5 2 Install Cylinder head assembly 2 Cylinder head bolts 1 to 5 TIP Tighten the bolt...

Page 63: ...3 25 1 2 3 4 5 6 7 8 9 10 ENGINE CYLINDER HEAD COVERS CYLINDER HEADS Cylinder head bolt 1st 12 N m 1 2 kgf m 8 9 lb ft 2nd 50 N m 5 0 kgf m 37 lb ft T R ...

Page 64: ...isted The following procedure applies to both cylin ders Cylinder head assembly Refer to CYLINDER HEAD COVERS CYL INDER HEADS on page 3 19 1 Valve cotter 3 2 Valve spring retainer 3 3 Intake valve spring 2 4 Exhaust valve spring 1 5 Intake valve 2 6 Exhaust valve 1 7 Valve stem seal 3 8 Valve spring seat 3 1 2 4 5 6 7 8 1 2 3 7 8 2 3 7 8 ...

Page 65: ...ALVE SPRINGS The following procedure applies to all of the valves valve springs and related components 1 Measure Valve stem length a Valve head diameter b Out of specifications Replace TIP Intake and exhaust springs are different Do not mix 1 2 3 4 5 6 7 Do not compress the valve spring more than neces sary Valve spring compressor 90890 01253 NOTICE b a Valve stem length Intake 88 8 mm 3 4961 in V...

Page 66: ...ace 5 Measure Compressed valve spring force a Out of specification Replace a Valve stem diameter Intake 5 948 5 963 mm 0 2342 0 2348 in Valve stem diameter Exhaust 5 940 5 955 mm 0 2339 0 2344 in Limit Intake 5 918 mm 0 2330 in Limit Exhaust 5 910 mm 0 2327 in Valve stem runout limit 0 01 mm 0 0004 in a Valve spring free length Intake 37 1 mm 1 4606 in Valve spring free length Exhaust 35 6 mm 1 40...

Page 67: ...e and valve seat 2 Apply a small amount of coarse mechanic s blue lay out fluid to the valve face a 3 Insert the valve into the valve guide and use a valve lapper to contact the valve face with the valve seat TIP Do not rotate the valve while the valve face is contacting the valve seat Installed compression spring force Intake 67 7 N 6 90 kgf 15 2 lbf Installed compression spring force Exhaust 118...

Page 68: ...evenly on the valve face Lap the valve by tapping and rotating the valve lapper clockwise and counterclockwise 2 Clean off all of the lapping compound from the valve face and valve seat Apply fine lapping compound on the valve face and lap the valve as described in step 1 a Valve face contact width Intake 0 9 1 1 mm 0 0354 0 0433 in Valve face contact width Exhaust 0 9 1 1 mm 0 0354 0 0433 in Limi...

Page 69: ...alve 1 Valve spring seat 2 Valve stem seal 3 Valve spring 4 Valve spring retainer 5 Valve cotter 6 Use the valve spring compressor 7 to install the parts Do not let the lapping compound enter the gap between the valve stem and the valve guide NOTICE 6 5 4 3 2 1 7 Valve spring compressor 90890 01253 New New a b Do not compress the spring more than necessary Surface a with the rounded edges of the v...

Page 70: ...ge 3 19 1 Collar 1 2 Crankcase cover 2 1 3 Dowel pin 2 4 Relief valve 1 5 Oil pump cover 1 6 Oil strainer cover 1 7 Oil strainer 1 8 Inner rotor 1 9 Outer rotor 1 10 Oil seal 1 11 Oil pressure switch 1 10 N m 1 0 kgf m 7 4 lb ft 27 N m 2 7 kgf m 20 lb ft 27 N m 2 7 kgf m 20 lb ft 30 N m 3 0 kgf m 22 lb ft 1 2 3 3 4 5 6 7 9 8 10 11 3 11 8 N m 0 8 kgf m 5 9 lb ft 30 N m 3 0 kgf m 22 lb ft 12 N m 1 2...

Page 71: ... 1 3 Remove Oil pump cover 1 4 Remove Oil strainer cover 1 Oil strainer 2 Inner rotor 3 Outer rotor 4 CHECKING THE OIL PUMP 1 Check Inner rotor 1 Outer rotor 2 Cracks damage wear Replace the defective part s 2 Check Oil strainer 1 Oil strainer cover 2 Damage Replace Contaminants Clean with solvent 1 1 1 2 3 4 1 2 1 2 ...

Page 72: ...wear seized Replace CHECKING THE CRANKCASE COVER 2 1 Check Crankcase cover 2 Damage Replace INSTALLING THE OIL PRESSURE SWITCH 1 Check Oil pressure switch Damage Replace 2 Install Oil pressure switch 1 a b Inner rotor to outer rotor tip clearance a 0 0 mm 0 0 in Inner rotor to outer rotor tip clearance b 0 19 0 35 mm 0 008 0 013 in Relief valve operating pressure reference data 342 538 kPa 3 42 5 ...

Page 73: ...ate Inner rotor Outer rotor 2 Install Outer rotor 1 Inner rotor 2 Oil strainer 3 Oil strainer cover 4 TIP Face portion a of the oil strainer cover downward as shown in the illustration and install it 3 Install Oil pump cover 1 Oil pump cover bolts 4 Install Relief valve 1 Recommended lubricant Engine oil 1 2 3 4 a 1 Oil pump cover bolt 10 N m 1 0 kgf m 7 4 lb ft T R 1 Relief valve 30 N m 3 0 kgf m...

Page 74: ...ase cover 2 mating surfaces 3 Install Crankcase cover 2 TIP Align the inner rotor a of the oil pump with the flat portion b of the crankshaft and install 4 Install Crankcase cover 2 bolts 1 to 11 TIP Tighten the bolts to the specified torque in two steps and in order from 1 to 11 Three bond No 1217G a b 11 1 2 3 4 5 6 7 8 9 10 11 Crankcase cover 2 bolt 1st 12 N m 1 2 kgf m 8 9 lb ft 2nd 30 N m 3 0...

Page 75: ...assembly Refer to CYLINDER HEAD COVERS CYL INDER HEADS on page 3 19 1 Crankcase cover 1 1 2 Dowel pin 2 3 Bearing 1 4 Bearing 1 5 Clip 2 6 Governor fork 1 7 Flyweight shaft assembly 1 8 Oil seal 1 9 Cover 2 1 10 Gasket 1 11 Scroll air shroud 1 1 2 2 3 4 5 6 7 8 9 10 11 8 5 5 9 N m 0 9 kgf m 6 6 lb ft 10 N m 1 0 kgf m 7 4 lb ft 10 N m 1 0 kgf m 7 4 lb ft 7 N m 0 7 kgf m 5 2 lb ft 30 N m 3 0 kgf m 2...

Page 76: ...der Job Parts to remove Q ty Remarks 12 Cover 1 1 13 Dowel pin 2 14 Reed valve 1 15 Oil seal 1 12 13 14 15 8 5 5 9 N m 0 9 kgf m 6 6 lb ft 10 N m 1 0 kgf m 7 4 lb ft 10 N m 1 0 kgf m 7 4 lb ft 7 N m 0 7 kgf m 5 2 lb ft 30 N m 3 0 kgf m 22 lb ft 12 N m 1 2 kgf m 8 9 lb ft 1st 2nd ...

Page 77: ...ng the pistons camshaft and crankshaft Remove the parts in the order listed 1 Camshaft 1 2 Valve lifter 4 3 Connecting rod cap 2 4 Crankshaft 1 5 Connecting rod 2 6 Piston pin circlip 4 7 Piston pin 2 8 Piston 2 9 Top ring 2 10 2nd ring 2 11 Oil ring 2 1 2 2 2 3 4 5 6 6 7 8 9 10 11 3 5 6 6 7 8 9 10 11 20 N m 2 0 kgf m 15 lb ft 20 N m 2 0 kgf m 15 lb ft ...

Page 78: ...rs 3 3 Remove Flyweight shaft assembly 1 Washer 2 TIP Remove the flyweight shaft assembly by tapping the weight shaft from outside of the crankcase cover 1 DISASSEMBLING THE FLYWEIGHT SHAFT ASSEMBLY 1 Remove Flyweight shafts 1 Weights 2 Collar 3 Washer 4 Circlip 5 Weight shaft 6 CHECKING THE FLYWEIGHT SHAFT ASSEMBLY 1 Check Flyweight shaft assembly move smoothly Rough movement Replace 1 2 3 3 2 1 ...

Page 79: ... SHAFT ASSEMBLY 1 Install Weight shaft 1 Circlip 2 Washer 3 Collar 4 Weights 5 Flyweight shafts 6 INSTALLING THE FLYWEIGHT SHAFT ASSEMBLY AND GOVERNOR FORK 1 Install Washer 1 Flyweight shaft assembly 2 2 Install Washers 1 Governor fork 2 Clips 3 3 Install Governor assembly Crankcase cover 1 Refer to INSTALLING THE CRANKCASE COVER 1 on page 3 46 6 6 6 5 4 3 2 1 New 2 1 1 1 2 3 ...

Page 80: ... following procedure applies to all of the camshaft and valve lifters 1 Remove Camshaft 1 TIP Remove the camshaft when the camshaft gear mark a and the crankshaft gear mark b are aligned 2 Remove Valve lifter 1 Intake Valve lifter 2 Exhaust CHECKING THE CAMSHAFT 1 Check Camshaft Crack damage wear Replace a b 1 1 1 2 2 Mark the valve lifters so as not to confuse them during reassembly NOTICE ...

Page 81: ... THE VALVE LIFTERS The following procedure applies to all of the valve lifters a b Camshaft lobe dimensions Lobe height a Intake 32 885 mm 1 2947 in Limit 32 785 mm 1 2907 in Lobe height a Exhaust 33 957 mm 1 3369 in Limit 33 857 mm 1 3330 in Base circle diameter b Intake 26 000 mm 1 0236 in Limit 25 900 mm 1 0197 in Base circle diameter b Exhaust 26 000 mm 1 0236 in Limit 25 900 mm 1 0197 in a a ...

Page 82: ...E LIFTERS AND CAMSHAFT The following procedure applies to all of the camshaft and valve lifters 1 Install Valve lifter 1 Intake Valve lifter 2 Exhaust 2 Install Camshaft 1 INSTALLING THE COVER 1 1 Clean Mating surfaces of the crankcase and the cover 1 with a cloth dampened with lacquer thinner 1 1 2 2 a b 1 Be sure to align the camshaft gear mark a with the crankshaft gear mark b NOTICE ...

Page 83: ...e in order from 1 to 5 INSTALLING THE COVER 2 1 Install Gasket Cover 2 Cover 2 bolts 1 to 5 TIP Tighten the bolts to the specified torque in order from 1 to 5 CHECKING THE CRANKCASE COVER 1 1 Check Crankcase cover 1 Damage Replace Bearing Noise wear rotational failure Replace Three bond No 1217G 5 1 2 3 4 5 Cover 1 bolt 9 N m 0 9 kgf m 6 6 lb ft T R 5 1 2 3 4 5 Cover 2 bolt 10 N m 1 0 kgf m 7 4 lb...

Page 84: ...wall Cylinder wall Vertical scratches Replace the cylinder and replace the piston and piston rings as a set 2 Measure Cylinder warpage TIP Measure the warpage on the contact surface of the cylin der head at six points using a straight edge and feeler gauge set Out of specification Replace the crankcase assembly 3 Measure Piston to cylinder clearance a Measure cylinder bore C with the cylinder bore...

Page 85: ...If out of specification replace the piston and piston rings as a set e Calculate the piston to cylinder clearance with the following formula f If out of specification replace the crankcase assembly and replace the piston and piston rings as a set Bore 80 000 80 020 mm 3 1496 3 1504 in Warpage limit 80 025 mm 3 1506 in C maximum of D1 D2 D3 D4 D5 D6 P a Piston diameter 79 959 79 980 mm 3 1480 3 148...

Page 86: ...ications Replace 3 Measure Piston pin diameter a Out of specification Replace 4 Check Check that the piston pin enters smoothly into the piston pin hole TIP If the piston pin fits too tight into the piston check the pis ton pin hole If there is any protrusion use a knife or scraper to gently remove it so that piston pin can be pushed in smoothly with your fingers CHECKING THE PISTON RINGS The foll...

Page 87: ...m the piston ring grooves and pis ton rings 2 Install Piston ring into the cylinder TIP Use the piston crown to level the piston ring near bottom of cylinder a where cylinder wear is lowest 3 Measure Piston ring end gap Out of specification Replace the piston rings as a set Piston ring Top ring Side clearance 0 04 0 08 mm 0 0016 0 0031 in Limit 0 13 mm 0 0051 in 2nd ring Side clearance 0 03 0 07 m...

Page 88: ...icator gauge 3 Measure Crank pin outside diameter a Out of specification Replace Use a micrometer Top ring End gap installed 0 20 0 35 mm 0 0079 0 0138 in Limit 0 60 mm 0 0236 in 2nd ring End gap installed 0 20 0 35 mm 0 0079 0 0138 in Limit 0 60 mm 0 0236 in Oil ring End gap installed 0 20 0 70 mm 0 0079 0 0276 in 1 Dial indicator gauge YU A8428 Runout limit 0 03 mm 0 0012 in a Crank pin outside ...

Page 89: ... and connecting rod cap 2 Install Connecting rod 1 Connecting rod cap 2 TIP Tighten the cap bolts so that the crankshaft does not move while the oil clearance is being measured 3 Remove Connecting rod cap Connecting rod 4 Measure Connecting rod big end oil clearance Out of specification Replace crankshaft or con necting rod assembly and then measure the clear ance again TIP Measure the widest port...

Page 90: ... mark a faces toward the piston head Be sure to install the 2nd ring so that the RN mark b faces toward the piston head Make sure that the piston rings move smoothly 2 Apply the engine oil to the inside of the connecting rod small end 3 Install Piston 1 Piston pin 2 Piston pin circlips 3 TIP Make sure that the mark a on the piston head faces toward the flywheel Install the piston pin clips so that...

Page 91: ...ressor 1 TIP Attach the piston ring compressor to the piston and then insert the piston into the cylinder 4 Check Piston 1 with the connecting rod 1 1 position TIP Make sure that the mark a on the piston 1 head faces toward the flywheel Make sure that the 7UD mark b on the connecting rod 1 faces toward the crankcase cover 1 45 90 90 90 a b c d a Top ring oil ring expander b Lower oil ring rail c 2...

Page 92: ...t the YAMAHA mark b on the connect ing rod 2 faces toward the crankcase cover 1 6 Install Crankshaft 1 7 Install Connecting rod cap 1 1 Connecting rod cap 1 bolts 2 TIP Make sure that the mark a on the connecting rod 1 is aligned with the mark b on the connecting rod cap 1 Tighten the connecting rod cap 1 bolts alternately two to three times a 1 1 b 1 2 1 2 2 1 a b Connecting rod cap bolt 20 N m 2...

Page 93: ... the connecting rod 2 is aligned with the mark b on the connecting rod cap 2 Tighten the connecting rod cap 2 bolts alternately two to three times 9 Install Camshaft Refer to INSTALLING THE VALVE LIFTERS AND CAMSHAFT on page 3 44 Crankcase cover 1 Refer to INSTALLING THE CRANKCASE COVER 1 on page 3 46 2 1 2 2 1 a b Connecting rod cap bolt 20 N m 2 0 kgf m 15 lb ft T R ...

Page 94: ...3 56 1 2 3 4 5 6 7 8 9 10 ENGINE PISTONS CAMSHAFT CRANKCASE AND CRANKSHAFT MEMO ...

Page 95: ...MP Order Job Parts to remove Q ty Remarks Removing the fuel pump Remove the parts in the order listed 1 Fuel filter 1 2 Fuel hose 1 3 Fuel pump 1 4 Fuel pump bracket 1 5 Pulsar hose 1 6 Fuel delivery hose 1 7 N m 0 7 kgf m 5 2 lb ft 1 2 3 6 5 4 ...

Page 96: ...operation a Connect the manual vacuum pump Pressure vac uum tester 1 to the pulsar hose 2 b Place the container underneath the end of the fuel delivery hose 3 c Operate the manual vacuum pump Pressure vac uum tester 1 and check that gasoline is flowing out of the fuel delivery hose 3 d If not replace the fuel pump assembly 1 2 3 4 2 1 3 Pressure vacuum tester YB 35956 B ...

Page 97: ...he parts in the order listed Air filter case Refer to AIR FILTER on page 3 3 1 Governor spring 1 2 Governor assembly 1 3 Throttle lever comp 1 4 Link rod spring 1 1 5 Breather hose 1 6 Joint 1 1 7 Gasket 1 8 Carburetor assembly 1 9 Gasket 1 1 2 3 4 5 6 7 8 9 8 N m 0 8 kgf m 5 9 lb ft 7 N m 0 7 kgf m 5 2 lb ft 7 N m 0 7 kgf m 5 2 lb ft 1 1 N m 0 11 kgf m 0 81 lb ft ...

Page 98: ...oat chamber 1 3 Gasket 1 4 Float pin 1 5 Float 1 6 Needle assembly 1 7 Gasket 1 8 Main jet 1 Right 9 Main jet 1 Left 10 Main nozzle 2 11 Throttle stop screw Spring 1 1 12 Pilot jet 2 1 2 3 4 5 7 6 12 12 10 10 8 9 11 1 8 N m 0 18 kgf m 1 3 lb ft 1 6 N m 0 16 kgf m 1 2 lb ft 1 4 N m 0 14 kgf m 1 0 lb ft 1 4 N m 0 14 kgf m 1 0 lb ft 1 8 N m 0 18 kgf m 1 3 lb ft 1 6 N m 0 16 kgf m 1 2 lb ft 1 0 N m 0 ...

Page 99: ...ETOR ASSEMBLY 1 Check Carburetor assembly Cracks damage Replace 2 Check Throttle valve operation Throttle valve can not move smoothly Replace Engine speed adjustment Can not adjust engine high low engine speed by procedure on page 2 16 Replace INSTALLING THE CARBURETOR ASSEMBLY 1 Install Gaskets 1 Carburetor assembly 2 Joint 1 3 Breather hose 4 Carburetor assembly nuts 2 1 3 4 4 3 4 2 1 1 Carburet...

Page 100: ...y Install the governor spring to the throttle lever comp first and then to the governor assembly 3 Adjust Governor Governor assembly a Loosen the governor assembly bolt 1 b Turn the governor assembly 2 counterclockwise until it stops c Turn the governor fork 3 counterclockwise until it stops d Tighten the governor assembly bolt 1 4 Check Engine speed Refer to ENGINE SPEED on page 2 14 1 a b c d 1 ...

Page 101: ...er to RECTIFIER REGULATOR on page 3 8 Fuel pump Refer to FUEL PUMP on page 4 1 Oil cooler Refer to OIL COOLER on page 3 5 Fan case and fan Refer to CASE AND FAN on page 3 9 Carburetor assembly Refer to CARBURETOR ASSEMBLY on page 4 3 TCI unit Refer to TCI UNITS FLYWHEEL AND STA TOR COIL ASSEMBLY on page 3 13 1 Intake manifold 1 2 Intake manifold joint 2 3 Gasket 4 7 N m 0 7 kgf m 5 2 lb ft 3 0 N m...

Page 102: ...d joints Cracks damage Replace INSTALLING THE INTAKE MANIFOLD 1 Install Gaskets 1 Intake manifold joints 2 Intake manifold 3 2 Install Intake manifold nuts 1 4 and bolts 5 8 TIP Tighten the bolts and nuts to the specified torque in two steps and in order from 1 to 8 1 3 3 2 2 3 1 1 2 2 New 1 2 3 4 5 6 7 8 4 4 Intake manifold nut and bolt 1st 3 0 N m 0 30 kgf m 2 2 lb ft 2nd 7 N m 0 7 kgf m 5 2 lb ...

Page 103: ...4 9 1 2 3 4 5 6 7 8 9 10 FUEL INTAKE MANIFOLD MEMO ...

Page 104: ...5 1 1 2 3 4 5 6 7 8 9 10 ELECTRICAL ELECTRICAL CIRCUIT DIAGRAM G W W W B W B W B R R B W W R R L Br G OFF ON R B START W R L Br G G W Br G R L 250Ω LED 2 3 1 2 1 7 8 9 0 w e 4 5 6 q ...

Page 105: ...g 8 Mil light 2 TCI unit 9 Oil warning light 3 TCI magneto 10 Battery 4 Rectifier regulator 11 Rollover switch 5 Starter relay 12 Fuel cut solenoid 6 Starter motor 13 Oil pressure switch 7 Main switch B Black B W Black White G Green Br G Brown Green R Red R L Red Blue W White ...

Page 106: ...5 3 1 2 3 4 5 6 7 8 9 10 ELECTRICAL ELECTRICAL COMPONENTS ELECTRICAL COMPONENTS 1 3 4 5 2 2 ...

Page 107: ...5 4 1 2 3 4 5 6 7 8 9 10 ELECTRICAL ELECTRICAL COMPONENTS 1 Oil pressure switch 2 TCI unit 3 Stator coil assembly 4 Rectifier regulator 5 Starter motor ...

Page 108: ... Drain Engine oil 2 Disconnect Oil pressure switch lead 3 Connect Digital circuit tester between the engine ground and oil pressure switch terminal 4 Check Oil pressure switch continuity No continuity Replace the oil pressure switch CHECKING THE TCI UNIT RESISTANCE The following procedure applies to all of the TCI units 1 Check Coil resistance Out of specification Replace Ω O L Never insert the te...

Page 109: ...ng with step 4 Refer to IGNITION SYSTEM on page 6 1 TIP If the ignition spark gap is within specification the ignition system circuit is operating normally a Disconnect the spark plug cap 1 from the spark plug b Connect the ignition checker 2 as shown c Turn the main switch to START d Measure the ignition spark gap a Coil resistance 8 8 11 9 k 1 2 Model 88 Multimeter with tachometer YU A1927 Posit...

Page 110: ...s shown c Measure the spark plug cap resistance CHECKING THE STATOR COIL ASSEMBLY 1 Disconnect Stator coil connector from the wire harness 2 Check Stator coil resistance Out of specification Replace the stator coil assembly a Connect the digital circuit tester to the stator coil connector as shown Spark plug cap resistance 3 75 6 25 k 1 2 Model 88 Multimeter with tachometer YU A1927 Positive teste...

Page 111: ...ator harness b Start the engine c Measure the regulated voltage CHECKING THE STARTER MOTOR OPERATION 1 Check Starter motor operation Does not operate Perform the electric starting system troubleshooting starting with step 3 Refer to ELECTRIC STARTING SYSTEM on page 6 2 Positive tester probe White Negative tester probe White Regulated voltage 14 15 V Model 88 Multimeter with tachometer YU A1927 Pos...

Page 112: ...or operation c Disconnect the main switch coupler d Connect the jumper lead 1 to the starter relay coupler e Check the starter motor operation 1 A wire that is used as a jumper lead must have at least the same capacity of the battery lead other wise the jumper lead may burn This check is likely to produce sparks therefore make sure no flammable gas or fluid is in the vicin ity WARNING 1 ...

Page 113: ...EM REMOVING THE STARTER MOTOR Order Job Parts to remove Q ty Remarks Removing the starter motor Remove the parts in the order listed 1 Starter relay terminals 1 Disconnect 2 Earth terminal 1 Disconnect 3 Starter motor assembly 1 1 2 3 9 N m 0 9 kgf m 6 6 lb ft 23 N m 2 3 kgf m 17 lb ft ...

Page 114: ...Q ty Remarks Disassembling the starter motor Disassemble the parts in the order listed 1 Rear bracket 1 2 Insulator 1 3 Brush spring 4 4 Brush 4 5 Yoke 1 6 Armature 1 7 Starter relay 1 8 Starter drive lever 1 9 Starter case 1 1 2 3 4 5 6 7 8 9 11 N m 1 1 kgf m 8 1 lb ft 9 N m 0 9 kgf m 6 6 lb ft 6 N m 0 6 kgf m 4 4 lb ft ...

Page 115: ...blade which has been grounded to fit the commutator TIP The mica insulation of the commutator must be undercut to ensure proper operation of the commutator 3 Measure Armature coil insulation continuity Defects Replace the starter motor Connect the digital circuit tester to the armature coil a Depth of insulator a 2 0 mm 0 079 in Model 88 Multimeter with tachometer YU A1927 Commutator continuity Co...

Page 116: ...ce CHECKING THE STARTER RELAY 1 Measure Magnetic switch coil resistance Connect the digital circuit tester to the magnetic switch Out of specification Replace ASSEMBLING THE STARTER MOTOR 1 Install Starter drive lever 1 1 1 2 Brush wear limit length 6 0 mm 0 2362 in Model 88 Multimeter with tachometer YU A1927 A B C Holding coil resistance A B 0 88 1 32 Pull in coil resistance A C 0 4 0 6 1 ...

Page 117: ...5 14 1 2 3 4 5 6 7 8 9 10 ELECTRICAL ELECTRIC STARTING SYSTEM 2 Install Armature and starter drive lever 1 3 Install Starter relay 1 1 1 Starter relay nut 11 N m 1 1 kgf m 8 1 lb ft T R ...

Page 118: ...5 15 1 2 3 4 5 6 7 8 9 10 ELECTRICAL ELECTRIC STARTING SYSTEM MEMO ...

Page 119: ...he spark plugs 3 Check the ignition spark gap Refer to CHECKING THE IGNITION SPARK GAP on page 5 6 If the ignition spark gap is OK the igni tion system is OK 4 Check the spark plug cap resistance Refer to CHECKING THE SPARK PLUG CAPS on page 5 7 Replace the spark plug cap 5 Check the TCI units Refer to CHECKING THE TCI UNIT RESISTANCE on page 5 5 Replace the TCI units 6 Check the main switch Repla...

Page 120: ...operation Refer to CHECKING THE STARTER MOTOR OPERA TION on page 5 8 If the starter motor operates normally the starter motor is OK 3 Check the starter motor Refer to ELECTRIC STARTING SYSTEM on page 5 10 Repair or replace the starter motor 4 Check the main switch Replace the main switch 5 Check the entire starting system s wiring Refer to CIRCUIT DIAGRAM on page 5 1 Properly connect or repair the...

Page 121: ... fuel pump Refer to FUEL PUMP on page 4 1 Replace the fuel pump 6 Check the low engine speed Refer to ENGINE SPEED on page 2 14 Adjust the low engine speed 7 Measure the valve clearance Refer to ADJUSTING THE VALVE CLEARANCE on page 2 9 Adjust the valve clearance 8 Check the compression pressure Refer to MEASURING THE COMPRESSION PRES SURE on page 3 1 Too high Decarbonize the combustion chamber if...

Page 122: ...eposits Too low Next checking steps 6 Check governor setting Refer to INSTALLING THE CARBURETOR ASSEMBLY on page 4 5 Adjust the governor 7 Check the valve face and valve seat for wear Refer to VALVES on page 3 26 Resurface or replace the valve face and valve seat 8 Check if the marks on the crankshaft and camshaft are aligned Refer to INSTALLING THE VALVE LIFTERS AND CAM SHAFT on page 3 44 Correct...

Page 123: ...n the carburetor assembly nuts securely Replace the carburetor assembly joint or gasket with a new one 5 Check if the main passages such as the carburetor assem bly are clogged Clean the parts 6 Check the valve clearance Refer to ADJUSTING THE VALVE CLEARANCE on page 2 9 Adjust the valve clearance 7 Check the valve face and valve seat for wear Refer to VALVES on page 3 26 Resurface or replace the ...

Page 124: ...Check the stator coil Refer to CHECKING THE STATOR COIL ASSEMBLY on page 5 7 Replace the stator coil assembly 3 Check the rectifier regulator Refer to CHECKING THE RECTIFIER REGULATOR on page 5 8 Replace the rectifier regulator 4 Check the entire charging system s wiring Refer to CIRCUIT DIAGRAM on page 5 1 Properly connect or repair the charging system s wiring 5 The charging system circuit is OK...

Page 125: ...ernor link operate smoothly Adjust or replace 2 Check that the governor spring is stretched Replace 3 Check the governor adjustment Refer to INSTALLING THE CARBURETOR ASSEMBLY on page 4 5 Adjust 4 Check the governor weight and governor bushing function Refer to CHECKING THE FLYWEIGHT SHAFT ASSEM BLY on page 3 40 Adjust or replace ...

Page 126: ...he oil if it is insufficient 4 Check the oil filter Replace the oil filter 5 Check the oil pressure switch Refer to CHECKING THE OIL PRESSURE SWITCH on page 5 5 Replace the oil pressure switch 6 Check the entire oil pressure system s wiring Refer to CIRCUIT DIAGRAM on page 5 1 Properly connect or repair the oil pres sure system s wiring 7 Check the oil pump Refer to CHECKING THE OIL PUMP on page 3...

Page 127: ...engine oil YAMALUBE SAE 10W 30 Performance All Purpose SAE 10W 30 or 10W 40 Recommended engine oil grade API Service SE type or higher Oil filter type Cartridge Lubrication system Full pressure with filter Air filter system Dry Cooling system Air cooled Starting system Electric starter Stopping system Misfire Rotating direction Counterclockwise From PTO shaft Governor type Centrifugal weight syste...

Page 128: ...7 2 1 2 3 4 5 6 7 8 9 10 SPECIFICATIONS GENERAL SPECIFICATIONS Use only unleaded gasoline The use of leaded gasoline will cause severe damage to internal engine parts NOTICE ...

Page 129: ...995 19 000 mm 0 7478 0 7480 in Limit 18 975 mm 0 7470 in Piston ring Top ring Type Barrel Dimensions 1 2 2 9 mm 0 0472 0 1142 in End gap installed 0 20 0 35 mm 0 0079 0 0138 in Limit 0 60 mm 0 0236 in Side clearance 0 04 0 08 mm 0 0016 0 0031 in Limit 0 13 mm 0 0051 in 2nd ring Type Taper Dimensions 1 0 2 5 mm 0 0394 0 0984 in End gap installed 0 20 0 35 mm 0 0079 0 0138 in Limit 0 60 mm 0 0236 in...

Page 130: ... mm 1 0197 in Base circle diameter Exhaust 26 000 mm 1 0236 in Limit 25 900 mm 1 0197 in Camshaft journal diameter 16 965 16 990 mm 0 6679 0 6689 in Limit 16 950 mm 0 6673 in Valve Valve dimensions Valve head diameter Intake 27 9 28 1 mm 1 0984 1 1063 in Valve head diameter Exhaust 34 9 35 1 mm 1 3740 1 3819 in Valve stem diameter Intake 5 948 5 963 mm 0 2342 0 2348 in Valve stem diameter Exhaust ...

Page 131: ...e inside diameter Intake 12 000 12 018 mm 0 4724 0 4731 in Rocker arm shaft hole inside diameter Exhaust 12 000 12 018 mm 0 4724 0 4731 in Rocker arm shaft diameter Intake 11 981 11 991 mm 0 4717 0 4721 in Rocker arm shaft diameter Exhaust 11 981 11 991 mm 0 4717 0 4721 in Oil clearance 0 08 mm 0 0031 in Valve spring Valve spring free length Intake 37 1 mm 1 4606 in Valve spring free length Exhaus...

Page 132: ...0 MX825V Bore size ø28 Main jet 1 19 mm 0 046 in Left 1 15 mm 0 045 in Right Main air jet 1 2 mm 0 047 in Pilot air jet 0 9 mm 0 035 in Pilot outlet 0 95 1 05 mm 0 037 0 041 in Valve seat size 1 58 1 62 mm 0 062 0 063 in Main nozzle 2 5 mm 0 0984 in Pilot jet 0 46 mm 0 018 in Left 0 46 mm 0 018 in Right Pilot screw 1 75 4 25 turns out Throttle valve 17 Governor assembly Tension spring attach hole ...

Page 133: ...ut at 3600 r min 25 A More than 25 A Stator coil resistance 25 A 0 096 0 144 at 23 C 73 4 F Rectifier regulator Regulator type Single phase full wave rectification Regulated voltage 14 15 V Rectifier capacity 25 A Electric starting system Depth of insulator 2 0 mm 0 079 in Insulation resistance More than 1 0 M Brush spring pressure 11 73 15 35 N 1 196 1 565 kgf 2 637 3 451 lbf Brush wear limit len...

Page 134: ...e cover bolt M6 1 0 7 N m 0 7 kgf m 5 2 lb ft Oil filler pipe bolt M6 1 0 7 N m 0 7 kgf m 5 2 lb ft Stator coil assembly bolt M6 1 0 7 N m 0 7 kgf m 5 2 lb ft Flywheel nut M22 1 5 180 N m 18 kgf m 133 lb ft Cylinder air shroud bolt M6 1 0 7 N m 0 7 kgf m 5 2 lb ft Cylinder head cover bolt M6 1 0 11 N m 1 1 kgf m 8 1 lb ft Rocker arm shaft bolt M5 1 0 4 0 N m 0 40 kgf m 3 0 lb ft Cylinder head bolt...

Page 135: ...5 9 N m 0 9 kgf m 6 6 lb ft Starter motor rear bracket bolt M6 0 8 6 N m 0 6 kgf m 4 4 lb ft Starter relay nut M6 1 0 11 N m 1 1 kgf m 8 1 lb ft Drain screw 1 4 N m 0 14 kgf m 1 0 lb ft Float chamber screw 1 8 N m 0 18 kgf m 1 3 lb ft Float screw 1 0 N m 0 10 kgf m 0 73 lb ft Throttle valve screw 1 6 N m 0 16 kgf m 1 2 lb ft Choke valve screw 1 6 N m 0 16 kgf m 1 2 lb ft Pilot jet screw 1 8 N m 0 ...

Page 136: ... assemblies are included in the applicable sections of this book To avoid warpage tighten multi fastener assemblies in a crisscross fashion in progressive stages until full torque is reached Unless otherwise specifications call for clean dry threads Components should be at room temperature Thread size Tightening torque N m kgf m lb ft M4 2 0 0 20 1 5 M5 3 0 0 30 2 2 M6 7 0 7 5 2 M7 10 1 0 7 4 M8 1...

Page 137: ...haft journal Connecting rod cap bolt Piston pin Piston Valve stem Valve stem end Valve rocker arm shaft Valve push rod end Valve lifter stem Camshaft lobe Camshaft gear teeth Camshaft journal Adjusting pad Inner rotor Outer rotor Governor collar internal surface Governor fork meet surface Governor weight moving point Oil pressure switch Crankcase cover 2 Three bond No 1217G Cover 1 Three bond No 1...

Page 138: ...7 12 1 2 3 4 5 6 7 8 9 10 SPECIFICATIONS WIRE ROUTING DIAGRAM WIRE ROUTING DIAGRAM UPPER SIDE VIEW ...

Page 139: ... 3 4 5 6 7 8 9 10 SPECIFICATIONS WIRE ROUTING DIAGRAM 1 Fuel delivery hose 4 Hose clamp 2 Intake manifold 5 Stay 3 Carburetor assembly A Install yellow painted portion in the direction shown in the illustration ...

Page 140: ...7 14 1 2 3 4 5 6 7 8 9 10 SPECIFICATIONS WIRE ROUTING DIAGRAM ...

Page 141: ...tie 7 Wire harness 4 Intake manifold A Direction of upper surface of the engine B Allowance 2 0 mm 0 08 in or less C Install the lock of the plastic locking tie as shown in the illustration D Projection E Fix to fit the projection F The wiring of TCI unit 1 is crossed over the wiring of TCI unit 2 G Align the wiring along the intake manifold ...

Page 142: ...7 16 1 2 3 4 5 6 7 8 9 10 SPECIFICATIONS WIRE ROUTING DIAGRAM LEFT SIDE VIEW ...

Page 143: ...l together with the mounting bolt in the direction shown in the illustration B Install the spark plug cap in the direction shown in the illustration C Engine side D Tighten together with the vehicle battery positive terminal E Starter motor lead installation details F Connect with the magneto assembly lead connector female Polarity does not matter G Connect with the wire harness connector male bla...

Page 144: ...7 18 1 2 3 4 5 6 7 8 9 10 SPECIFICATIONS WIRE ROUTING DIAGRAM RIGHT SIDE VIEW ...

Page 145: ... be fixed securely to the groove of the case B Insert the hose until it reaches the end as shown in the illustration C Install white painted portion in the direction shown in the illustration D Pulsar hose installation details E Keep the length shown in the illustration to 0 2 0 mm 0 0 008 in and cut off the end of the plastic lock ing tie F The position of the binding area of the plastic locking ...

Page 146: ...7 20 1 2 3 4 5 6 7 8 9 10 SPECIFICATIONS WIRE ROUTING DIAGRAM ...

Page 147: ...way into the oil cooler B Face the projection inward C Install the white painted portion in the direction shown in the illustration D 8 12 mm 0 31 0 47 in E Install the hose clamp in the direction shown in the illustration F Install the yellow painted portion in the direction shown in the illustration G 2 0 4 0 mm 0 08 0 16 in H Face the projection outward ...

Page 148: ...7 22 1 2 3 4 5 6 7 8 9 10 SPECIFICATIONS WIRE ROUTING DIAGRAM ...

Page 149: ... 9 10 SPECIFICATIONS WIRE ROUTING DIAGRAM 1 Oil pressure switch lead 4 Oil pressure switch 2 Pulsar hose 5 Spark plug cap 3 Fuel hose A Oil pressure switch lead routing direction B Direction of upper surface of the engine ...

Page 150: ...7 24 1 2 3 4 5 6 7 8 9 10 SPECIFICATIONS WIRE ROUTING DIAGRAM REAR SIDE VIEW ...

Page 151: ...the screw in the direction shown in the illustration D Insert the air filter cover 1 until it contacts the air filter case E Installation angle of joint 2 15 75 reference value F Install the joint 2 in the direction shown in the illustration G Insert from 22 mm 0 87 in until contact is made as shown in the illustration H The air filter case and joint 2 should not be bent or detached due to unreaso...

Page 152: ...7 26 1 2 3 4 5 6 7 8 9 10 SPECIFICATIONS WIRE ROUTING DIAGRAM ...

Page 153: ...AM 1 Fuel cut solenoid lead 4 Carburetor assembly lead red 2 Clamp 5 Carburetor assembly lead green 3 Fuel cut solenoid lead red blue 6 Fuel cut solenoid lead black A Main switch coupler B Secure with a clamp so as not to get caught when assembling the fan case ...

Page 154: ...APPENDIX CIRCUIT DIAGRAM G W W W B W B W B R R B W W R R L Br G 250Ω LED OFF ON START 2 3 1 2 1 7 8 9 0 w e 4 5 6 q ...

Page 155: ... Oil warning light 3 TCI magneto 10 Battery 4 Rectifier regulator 11 Rollover switch 5 Starter relay 12 Fuel cut solenoid 6 Starter motor 13 Oil pressure switch 7 Main switch B Black B W Black White G Green Br G Brown Green R Red R L Red Blue W White ...

Page 156: ...MEMO ...

Page 157: ...7UC F8197 E0_Hyoshi indd 3 4 2017 10 27 13 08 23 ...

Page 158: ...SERVICE MANUAL MX800V MX825V 7UC F8197 E0 LIT 19616 02 50 2017 10 1 7UC F8197 E0_Hyoshi indd 1 2 2017 10 27 13 08 23 ...

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