Yamaha LB50IIAC Service Manual Download Page 58

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Summary of Contents for LB50IIAC

Page 2: ... AC LBBO II AC SERVICE MANUAL 1997 by Yamaha Motor Co Ltd First edition March 1997 All rights reserved Any reproduction or unauthorized use without the written permission of Yamaha Motor Co Ltd is expressly prohibited ...

Page 3: ...INDEX GENERAL INFORMATION PERIODIC INSPECTIONS AND ADJUSTMENTS ENGINE OVERHAUL CARBURETION CHASSIS ELECTRICAL APPENDICES ...

Page 4: ... GENERAL INFORMATION FEATURES 1 MACHINE IDENTIFICATION 5 EXTERNAL VIEW 6 SPECIFICATIONS 8 GENERAL SPECIFICATIONS 8 MAINTENANCE SPECIFICATIONS 11 GENERAL TORQUE SPECIFICATIONS 19 CABLE ROUTING 20 SPECIAL TOOLS 29 ...

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Page 6: ...d automatically 1 1st drive gear 9 Spring 16 low range 2 Clutch housing 10 2nd drive gear 17 High range 3 1st clutch 11 Shift rod 18 Drive axle 4 2nd clutch 12 Main axle 19 1st driven gear 5 One way clutch 13 One way clutch 20 Spring 6 Crankshaft 14 2nd driven gear 21 Kick gear 7 Shift lever 15 Sprocket 22 Kick crank 8 Kick pinion 1 ...

Page 7: ...r 1st gear operation 2nd gear clutch For automatic change to 2nd gear 1 Each clutch has three clutch shoes operated by centrifugal force These shoes are well balanced to minimize the vibration for smooth operation This clutch is provided with linings of high wear resistance and thus excellent clutching power is guaranteed The heat generated by friction between shoes and lining is quickly dissipate...

Page 8: ...ine is transmitted to the main axle through 1st drive and driven gears 3 Reduction and 2nd gear As the throttle grip is further opened the 2nd side clutch begins to operate That is the clutch shoes are forced against the clutch housing by the weights and thus the engine power is transmitted through 2nd drive and driven gears to the main axle At this stage the 1st gear side clutch is released becau...

Page 9: ...h down the stopper lever and then set the shift lever to L Kick starter mechanism 1 Both kick idle gear and kick pinion are helically meshed When kicked thrust is exerted on the pinion thus causing it to move off the drive axle 2 When the kick crank returns to its home position after the engine is started the kick pinion is forced back by the return spring 1 Dock 2 Main axle 3 Driven gear 4 Drive ...

Page 10: ... production number of the unit The engine serial number is located on a rais ed boss on the upper front left hand side of the engine Engine identification follows the same code as frame identification Normally both serial numbers are identical however on occasion they may be two or three numbers off Starting Serial Number 439 1000101 LB50 II AC 34H 010101 LB80 II AC Frame serial number Engine seri...

Page 11: ...EXTERNAL VIEW LB50 II AC 1 ww oiL i 6 E E 0 E E o_ ...

Page 12: ...LB80IIAC WW QLL 7 E E E E 0 q ...

Page 13: ...inclined Displacement 49 cm3 Bore x stroke 40 0 x 39 7 mm Compression ratio 6 6 1 Starting system Kick starter Lubrication system Separate lubrication Yamaha autolube Oil type or grade Engine oil Air cooled 2 stroke engine oil Transmission oil SAE 10W30 type SE motor oil Oil capacity Oil tank engine oil 1 4 L Transmission oil Periodic oil change 0 65 L Total amount 0 7 L Air filter Wet type elemen...

Page 14: ...2 188 29 15 1 933 Chassis Frame type Steel tube underbone f Caster angle 26 f Trail 45mm f Tire Type With tube f Size front 4 00 8 4PR f rear 4 00 8 4PR f Manufacturer front INOUE f rear INOUE f Tire pressure cold tire Loading condition A 0 70 kg 0 74 kg front 100 kPa 1 00 kg cm f 1 00 bar rear 125 kPa 1 25 kg cm f 1 25 bar Loading condition B 70 140 kg 74 144kg front 100 kPa 1 00 kg cm f 1 00 bar...

Page 15: ...er Wheel travel Front wheel travel 75 mm Rear wheel travel 84mm 80 mm Electrical Ignition system C D I Generator system Flywheel magneto Battery type 6N4 2A 2 Battery capacity 6 V 4 AH Headlight type Bulb type Bulb wattage x quantity Headlight 6 V 25 W 25 W Tail I brake light 6 V 5 3 WI 17 w Flasher light 6V10Wx4 Meter light 6V3Wx1 High beam indicator light 6V3Wx1 Oil level indicator light 6V3Wx1 ...

Page 16: ... inside diameter Piston pin outside diameter Piston rings Top ring 1st 2nd CJ s Type Dimensions Bx T End gap installed I T I Side clearance installed LB50 II AC 0 03 mm 40 00 40 02 mm 0 05 mm 0 01 mm 0 025 0 030 mm 0 1 mm 39 94 40 00 mm 5mm 40 25 mm 40 5 mm 0 2 mm EX side 12 004 12 015 mm 11 996 12 000 mm Key stone 1 5 x 1 8 mm 0 15 0 35 mm 0 03 0 05 mm 11 LBBO IIAC 47 00 47 02 mm f f 46 94 47 00 ...

Page 17: ... f Runout limit C 0 015 mm f Big end side clearance D 0 20 0 50 mm f Big end radial clearance E 0 004 0 015 mm 0 004 0 017 mm Small end free play F 0 8 2 0 mm f Automatic centrifugal clutch Clutch shoe thickness 2 5mm f Wear limit 2 mm f Clutch stall revolution 2 800 3 200 r min 2 700 3 200 r min Transmission Main axle deflection limit 0 015 mm f Drive axle deflection limit 0 015 mm f Kick starter...

Page 18: ...5 s Pilot jet P J 17 5 15 Air screw AS 1 1 3 4 Valve seat size V S 1 2 s Starter jet G S 1 20 25 Float heigh F H 22 0 2 5 mm s Engine idle speed 1 250 1 450 r min s Reed valve Thickness 0 15 mm s Valve stopper height 6 8 7 2 mm s Valve bending limit 0 3 mm s Lubrication system Autolube pump Plunger diameter 3 5mm 4 0 mm Color code Grey Brown Minimum stroke 0 20 0 25 mm 0 25 0 30 mm Maximum stroke ...

Page 19: ...ty left 96 cm3 r right 120 cm3 r Oil grade Fork oil 10W or equi r valent Rear suspension Shock absorber travel 65 mm r Spring free length 212 mm r Fitting length 207 mm r Spring rate K1 21 0 N mm 2 1 kg mm r K2 28 5 N mm r 2 85 kg mm Stroke K1 O 34 mm r K2 34 65 mm r Optional spring No r Swingarm Free play limit end 1 mm r side 0 5 mm r Front wheel Type Disc wheel r Rim size 2 50C x 8 r Rim materi...

Page 20: ...um inside diameter 110 mm c Limit 111 mm c Lining thickness 4mm c Limit 2 mm c Shoe spring free length 50 5 mm c Rear drum brake Type Leading trailing c Brake drum inside diameter 110 mm c Limit 111 mm c Lining thickness 4mm c Limit 2 mm c Shoe spring free length 50 5 mm c Brake lever brake pedal Brake lever free play at pivot 5 8mm c Brake lever free play at lever end 10 20mm c 15 ...

Page 21: ...wheel axle M10 x 1 25 39 3 9 Rear wheel axle M12 x 1 25 60 6 0 Pivot shaft M10 x 1 25 39 3 9 Rear shock absorber and bracket M12 x 1 25 59 5 9 Rear shock absorber and swing arm M12 x 1 25 59 5 9 Tension bar and brake shoe plate MS x 1 25 18 1 8 Tension bar and swingarm MS x 1 25 18 1 8 Sprocket and sprocket hub MS x 1 25 20 2 0 Brake camshaft lever M6 x 1 0 7 0 7 Wheel panel 1 and wheel panel 2 MS...

Page 22: ...ng resistance 5 68 8 52 kQ at 20 C f Spark plug cap Type Resin type f Resistance 5 kQ f Charging system Type Flywheel magneto f Flywheel magneto Model I manufacturer F4GC I YAMAHA f Charging current day min 0 8 A at 3 000 r min f max 2 A at 8 000 r min f Charging current night min 0 8 A at 3 000 r min f max 2 A at 8 000 r min f Charging coil resistance I color 0 30 0 44 Q at 20 C White Black f Lig...

Page 23: ...perage 1 5 A Flasher relay Type Condenser type Model I manufacturer FR 2212 I MITSUBA Self cancelling device No Flasher frequency 60 120 cycle min Wattage 10 Wx2 Oil level switch Model I manufacturer 2T5 I STANLEY Circuit breaker Type Fuse Amperage for individual circuits Main 10 Ax 1 Reserve 10 Ax 1 18 ...

Page 24: ...tighten multi fastener assemblies in a criss cross fashion in progressive stages until the specified torque is reached Unless oth erwise specified torque specifications require clean dry threads Components should be at room temperature A Distance between flats B Outside thread diameter A 8 nut bolt 10 mm 6mm 12 mm 8mm 14 mm 10mm 17 mm 12 mm 19 mm 14 mm 22 mm 16mm General torque specifications Nm m...

Page 25: ...tarter cable Rear brake switch lead Left handlebar switch lead Front brake cable Right handlebar switch Front brake switch lead Throttle cable 1 2 A 5 13 Horn switch lead Wire harness Rectifier regulator Rectifier regulator lead Cross bar Horn B c 15 20 10 El A 14 B ...

Page 26: ... Fasten the right handlebar switch lead and front brake switch lead with a plastic locking tie 5 4 2 A l5 Route the front brake cable to the right of the speedometer under the speedometer cable and out the lower left side of the vehicle III Route the throttle cable 1 to the right of the speedometer cable and out the lower left side of the vehicle III Route the horn switch lead in front of the cros...

Page 27: ...ake cable Rectifier regulator Rectifier regulator lead Wire harness 3 2 4 6 Speedometer cable Rear brake cable Left handlebar switch lead Rear brake switch lead Starter cable 12 J Fasten the wire cylinder ITll Pass the rectifier regulator lead and wire har ness through the cable guide 19 Faster the front brake cable and speedometer cable 14 c 22 ...

Page 28: ...Autolube pump J Oil feed hose Wire harness CDI magneto lead Fuel cock vacuum hose Fuel hose 2 I Band Mixing chamber air vent hose Carburetor Throttle cable 2 Starter cable Horn switch lead 6l Fasten the spark plug lead rear brake cable oil feed hose and wire harness with a plastic clip 8 9 23 ...

Page 29: ...I magneto lead route it to the right side 19 Route the fuel cock vacuum hose under the frame cross plate Q Pass the inside of slit on the plain of punched on crankcase II Pass the starter cable under throttle cable 2 24 8 9 ID ...

Page 30: ...il lead Ignition coil Battery breather hose 2 Spark plug lead CDI magneto lead Wire harness Pass the fuel hose through the inside of rear fender bracket ill Fasten the flasher relay lead and ignition coil lead on the left inside section of frame l J Fasten the spark plug lead on the right inside section of the frame A 11 D 25 ...

Page 31: ... QJ Fasten the battery breather hose on the right inside section of flame II Route the CDI magneto lead between the engine and the frame 2 D 26 A 11 ...

Page 32: ... switch A E l6l Fasten the tail I brake light switch lead and rear flasher light switch lead on the right side of the carrier El After routing the oil level switch lead through the inside of the flame connect the oil level switch coupler IT Route the rear brake cable between the engine and the frame Fasten the rear brake cable III After installing the rear brake cable attach the rubber boot D 27 O...

Page 33: ...ring sheathe is flush with the base of the oil tank IQ Route the tail brake light lead to inside of the rear shock absorber bracket BJ Fasten the tail brake light lead I Route the rear brake light switch leads to the inside of the frame A E D 28 ...

Page 34: ... 01235 This tool is used to hold the flywheel magneto and clutch assembly when removing or installing the securing nut Crankcase separating tool f P N 90890 01135 This tool is used when removing the crank shaft 29 Refer to the list provided to avoid errors when placing an order Dial gauge P N 90890 03097 This tool is necessary for adjusting the autol ube pump plunger stroke FOR ENGINE SERVICE Flyw...

Page 35: ...P N 90890 01403 This tool is used to loosen and tighten the steering ring nut 1 Ignition checker P N 90890 06754 This instrument is necessary for checking the ignition system components 30 FOR CHASSIS SERVICE FOR ELECTRICAL COMPONENTS Pocket tester P N 90890 03112 This instrument is invaluable for checking the electrical system ...

Page 36: ...ON INTERVALS 34 ENGINE 36 Carburetor 36 Air cleaner 36 Autolube pump 38 Engine and transmission oil 39 Cylinder head 41 CHASSIS 42 Fuel petcock 42 Front brake and wheel 42 Rear brake and wheel 43 Drive chain 43 Suspension steering and swing arm 45 ELECTRICAL 46 Spark plug 46 Battery 46 Headlight beam adjustment 47 ...

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Page 38: ...e operation and a longer service life The need for costly overhaul work will be greatly reduced This information not only applies to vehicles already in service but also to new vehicles that are being prepared for sale Any service technician performing preparation work should be familiar with this entire chapter SPECIAL TOOLS 1 Dial Gauge 2 Dial Gauge Stand 3 Torque Wrench 4 Steering Nut Wrench 5 ...

Page 39: ...jected to extremely hard usage and wet weather riding chain must be checked constantly See Lubrication Intervals for additional details No 2 AIR FILTER Remove and clean filter at least once per month or every 1 500 km LUBRICATION INTERVALS Item Remarks Type 500 Transmission oil change Warm engine before draining No 1 0 Drive chain Lube Adjust as required No 2 Drive chain Remove Clean Lube Adjust N...

Page 40: ...raphite base dry lubricant of quality manufacture may be used 4 Light duty Lithium soap base grease Heavy duty Standard chassis lube grease Do not use chassis lube grease on throttle throttle housing 5 Use a soft chassis lube grease 6 Medium weight wheel bearing grease of quality manufacture preferably waterproof 7 Light weight machine oil 8 Use Yamaha fork oil NOTE Drive chain must be lubricated ...

Page 41: ...ts but they must be adjusted at the same time to achieve optimum operating condition at engine idle speeds 5 Throttle cable After engine idle speed is set make cable free play adjustment at cable adjustor near throttle grip Loosen lock nut and turn adjustor until there is 0 5 1 0 mm free play between throttle cable housing and cable adjustor Retighten locknut Loosen cable adjustor locknut at top o...

Page 42: ...r case cover and cleaner seat 8 Re install the element assembly case cover and seat NOTE Each time cleaner element maintenance is performed check the air inlet to the cleaner case for obstructions Check the air cleaner joint rubber to the car buretor and manifold fittings for an air tight seal Tighten all fittings thoroughly to avoid the possibility of unfiltered air entering the engine CAUTION Ne...

Page 43: ...er hole Reinstall bleed screw 2 Oil pump wire adjustment a Remove the slack in throttle wire 2 by turning the adjusting screw attached to the carburetor b Loosen the locknut c Turn the adjusting screw so that the mark on the adjusting pulley is aligned with the Phillips head screw attached to the adjusting plate d Screw in the locknut until tight 1 Locknut 5 Phillips head screw 2 Wire adjusting sc...

Page 44: ... color code Gray l Brown Pulley adjust mark _____ I__ I _____ I__ Engine and transmission oil 1 Engine a Autolube oil 1 Adjust pulley 5 Locknut 2 Plunger 6 Adjusting plate 3 Min stroke 7 Dial gauge stand for oil pump 4 Adjusting bolt We recommend that first choice be Yamaha 2 cycle oil If for any reason you should use ano ther type the oil should meet or exceed BIA certification TC W Check contain...

Page 45: ...screw in Remove the level gauge and check level NOTE Be sure the machine is level and on both wheels b The stick has Minimum and Maximum marks The oil level should be between the two Top off as required Recommended oil SAE 10W 30 type SE motor oil c To change transmission oil remove the drain plug which is located on the bot tom ot the crankcase With the engine warm remove the plug and drain oil R...

Page 46: ...cluded with the transmission oil This oil also lubricates and cools the clutch Many additives will cause severe clutch slippage Cylinder head Check torque of cylinder head holding nuts Tighten in a crisscross pattern Cylinder head nut torque 10 Nm 1 0 m kg 41 ...

Page 47: ...djusted at handlebar lever or brake shoe plate a Loosen the adjuster locknut 2 b Turn the adjuster 1 in or out until ad justment is suitable c Tighten the adjuster locknut 2 2 Front axle a Check axle nut Front axle nut torque 39 Nm 3 9 m kg 3 Front tire pressure cold tire Model LB50IIAC LBSOII AC Basic weight With SO kg 76 kg oil and full fuel tank Maximum 140 kg 144 kg load Upto 70kg 100 kPa load...

Page 48: ...axle nut torque 60 Nm 6 0 m kg 3 Rear tire pressure cold tire Model LB50Il AC Basic weight With SO kg oil and full fuel tank Maximum 140 kg load LBSO Il AC 76 kg 144 kg Upto 70 kg 125 kPa load 1 25 kg cm2 1 25 bar 70kg maxi 200 kPa 150 kPa 2 0 kg cm2 1 5 kg cm2 mum load 2 0 bar 1 5 bar Load is the total weight of the cargo rider passenger and accessories Drive chain 1 Drive chain adjustment To adj...

Page 49: ...side and outside of chain Don t skip a portion as this will cause uneven wear Apply thoroughly Wipe off excess NOTE Choice of lubricant is determined by use and terrain SAE 20 wt or 30 wt motor oil may be used but Yamaha chain and cable lube offer more penetration and corrosion resistance for roller protec tion In certain areas semi drying lubricants are preferable These will resist picking up san...

Page 50: ...orks are turned NOTE Excessive tightening of this nut will cause rapid wear of ball bearings and races Re check for looseness and freedom of movement e Tighten steering fitting bolt NOTE After completing steering adjustment make certain forks pivot from stop to stop without binding If binding is notic ed repeat adjustment 2 Suspension a Check all suspension for proper opera tion b Check all suspen...

Page 51: ...Battery A poorly maintained battery will deteriorate quickly The battery fluid should be checked at least once a month 1 The level should be between the upper and lower level marks Use only distill ed water if refilling is necessary NOTE Normal tap water contains minerals which are harmful to a battery therefore refill only with distilled water 2 Always make sure the connections are correct when p...

Page 52: ...or maximum performance This initial charge will prolong the life of the battery Charging current 0 4A Charging hours 10 hrs Headlight beam adjustment When necessary adjust the headlight beam as follows 1 Adjust horizontally by tightening or loosening the adjusting screw as in the illustration To adjust to the right tighten the screw To adjust to the left loosen the screw 2 Adjust vertically by mov...

Page 53: ...ssion 57 Crankshaft assembly 58 INSPECTION AND REPAIRING 58 Cylinder head 58 Cylinder 59 Piston pin and bearing 59 Pi n 60 Piston rings 62 Autolube pump 63 Clutch 67 Kick starter 69 Sub Transmission 70 Crankshaft 71 Bearings and oil seals 72 Crankcase 73 ENGINE ASSEMBLING AND ADJUSTMENT 74 Crankshaft installation 74 Sub Transmission installation 75 Crankcase 79 Shifter 80 Kick starter assembly 80 ...

Page 54: ...Piston 83 Cylinder 83 Cylinder head 83 INSTALLING ENGINE 84 ...

Page 55: ... engine removal and disassembly be sure you have proper tools and clea ning equipment so you can perform a clean and efficient job 3 During disassembly of the engine clean and place all parts in trays in order of disassembly This will ease and speed assembly time and insure correct re installation of all engine parts 4 Start the engine and warm it for a few minutes turn off and drain transmission ...

Page 56: ...ump cable 9 Remove pump cover 2 and oil pipe Screw the oval counter sunk screw securing pump cover into oil pipe as il lustrated and tentatively place oil pipe over oil tank 10 Remove air cleaner joint 11 Remove the carburetor 51 ...

Page 57: ...g flywheel holder Note the position and direction of the washers Install flywheel puller on flywheel and tighten it NOTE The puller body has a lefthand thread While holding puller body tighten push bolt This will pull flywheel off the tapered end of the crankshaft Discon nect the magneto lead wires from the main harness 52 ...

Page 58: ...e screwed out by hand afterward Holding the engine with your left hand remove bolts 2 then re move bolt 3 2 The exhaust pipe should be moved down so that it does not obstruct the removal of the engine DISASSEMBLY Remove engine bracket and kick crank assembly Reed valve assembly Remove reed valve assembly holding bolts 4 carburetor joint and reed valve assembly 53 ...

Page 59: ...ing the piston pin clip cover the crankcase with a clean rag so you will not accidentally drop the clip into the crankcase 2 Push piston pin from opposite side then pull out Protect pin with rag as shown NOTE Before removing piston pin deburr clip groove and pin hole area Crankcase cover right Remove crankcase cover right holding bolts and the cover If the crankcase cover is hard to remove tap it ...

Page 60: ...heel on the crankshaft temporarily Then use the flywheel holding tool to hold the flywheel Loosen the clutch locknut 3 Remove 2nd gear clutch assembly 4 Remove 1st gear clutch assembly 55 i Cirdip 2 Gear holder 3 Primary drive gear 1 Flywheel holding tool 2 Torque wrench 1 2nd gear clutch assembly 1st gear clutch assembly ...

Page 61: ...riven gear Kick axle assembly Pull straight out the kick axle Shifter rod assembly Remove circlip from right side of the drive axle then remove shift spring spring retainer and shifter rod assembly 1 Clutch housing r j 1 1 One way clutch 2 Driven gear 56 ...

Page 62: ...ission shafts and the shift drum CAUTION Use soft hammer to tap on the case half Tap only on reinforced portions of case Do not tap on gasket mating surface Work slowly and carefully Make sure the case halves separate evenly If one end hangs up take pressure off the push screw realign and start over If the halves are reluctant to separate check for a remaining case screw or fitting Do not force Tr...

Page 63: ...mbustion chamber Take care to avoid damaging the spark plug threads Do not use a sharp instrument avoid scratching aluminium 3 Place on a surface plate There should be no warpage Correct by re surfacing as follows Place 400 600 grit wet sandpaper on surface plate and re surface head using a figure eight sanding pattern Rotate head several times to avoid removing too much material from one side 58 ...

Page 64: ...and maximum measurements If over to lerance and not correctable by honing rebore to next over size Max allowable taper 0 05 mm Max allowable out of round 0 01 mm Piston pin and bearing 1 Check the pin for signs of wear If any wear is evident replace pin and bearing 2 Check the pin and bearing for signs of heat discoloration If excessive heavily blued replace both NOTE Shiny spots on pin from race ...

Page 65: ...d bea ring surfaces Install in connecting rod small end Check for play There should be no noticeable vertical play If play exists check connecting rod small end for wear Replace pin and bearing or all as required 5 The piston pin should have no noticeable free play in piston If the piston pin is loose replace the pin and or the piston Piston 1 Remove piston ring 60 ...

Page 66: ...posits from piston crown 3 Remove carbon deposits from ring grooves 4 Remove score marks and lacquer deposits from sides of piston using 400 600 grit wet sandpaper Sand in a cross hatch pattern Do not sand excessively 61 ...

Page 67: ... 0 025 mm 0 030 mm Maximum wear limit 0 1 mm Piston rings 1 Check rings for scoring If any severe scratches are noticed replace set 2 Insert each ring into cylinder Push down approximately 20 mm using piston crown to maintain right angle to bore Measure installed end gap If beyond tolerance replace set Min Max Top ring end gap 0 15 mm 0 35 mm installed 2nd ring end gap 0 15 mm 0 35 mm installed 3 ...

Page 68: ... the plunger which is pushed back by the plunger return spring CD r CV Distributor 6 Inlet Plug 7 Outlet Inlet 8 Plunger 4 Plunger cam 9 Plunger return spring 5 Outlet 10 Plunger pin 63 l J DISCHARGE OF OIL 10 Adjusting bolt 11 Locknut 12 Adjust pulley Oil is forced out by the plunger when it is pushed by the plunger pin contacting the plunger cam The cam is meshed with the rotating distributor by...

Page 69: ...3 Removal and disassembly a Remove two Phillips screws securing pump to crankcase cover Remove pump b Disassembly is straight forward and can be accomplished by the parts il lustration 64 ...

Page 70: ...n 3 14 Bind screw 7 Bleeder bolt gasket 10 12 8 Shim 9 Adjusting plate 1O Hexagon nut 11 Adjusting bolt 12 Pan head screw 13 Pan head screw 14 Oil pump cover 1 65 14 15 15 Pan head screw 16 pan head screw 17 011 pump cover 2 18 pan head screw 19 Delivery pipe 20 Delivery pipe clip 21 Grommet ...

Page 71: ...ions LB50 II AC Maximum Throttle Min Max Minimum Throttle Min Max LB801IAC Maximum Throttle Min Max Minimum Throttle Min Max 5 Reassembly 0 55 mm 0 65 mm 0 20 mm 0 25 mm 0 80 mm 0 95 mm 0 25 mm 0 30 mm Always install a new pump case gasket 66 5 Loose fitting s allowing air entry to pump and or engine b If all inspections show no obvious problems and output is still suspect connect the delivery lin...

Page 72: ... emery cloth 3 Thoroughly clean the second clutch assembly and spacer Apply a light film of oil on the bushing surface and spacer Fit the spacer into the bushing It should be a smooth thumb press fit The spacer should rotate smoothly within the bushing 4 Thoroughly clean the clutch housing assembly and spacer Apply a light film of oil on the spacer into the bushing It should be a smooth thumb pres...

Page 73: ...replace as required NOTE The oneway clutch should be installed as illustrated with the hole in the side of the case directed outward 7 Check the oneway pawls pawl spring and driven gear for signs of wear heat damage etc If severe replace as re quired 1 2nd clutch 2 Spring j Pawl 2 Pawl spring 68 3 Driven gear j c i __ e I 3 Clutch housing boss 5 Cage 4 Roller 1 2nd gear clutch 2 Cage 3 Torsion spr...

Page 74: ...t wheel splined slides freely on the kick axle Check for burrs or other damage Replace as required 4 Check axle and wheel splines for wear The ratchet wheel is a fairly loose fit on splines However if wheel is so loose it catches on shaft keeping ratchet wheel spring from forcing it out replace 5 Check the ratchet wheel and kick gear for damage replace as required 6 Check the kick pinion gear seco...

Page 75: ...ation Check the gear teeth for signs of pitting galling or extreme wear Replace as required 2 Check to see that each gear moves free ly on its shaft 3 Check the shifter rod assembly for damage wear and fatigue of springs 70 G 6 1 Circlip 2 Washer 3 Shift spring I mn r 4 Spring retainer 5 Shifter rod ...

Page 76: ...m disassemble the crankshaft check amount of wear of crank pin and connecting rod crank pin and big bearing at big end end bearing Replace defective parts Play after reassembly should be within 0 8 1 0 mm Check the connecting rod side Move the connecting rod to one If excessive side clearance play is clearance at big end side and insert a feeler gauge present 0 6 mm or motor disas Big end side cle...

Page 77: ...red 2 Removal a Pry oil seal s out of place using a slotted head screwdriver Always replace all oil seals when overhauling engine NOTE Place a piece of wood under the screw driver to prevent damage to case b Drive out bearing s with socket and hammer NOTE Bearing s are most easily removed or installed if the cases are first heated to approximately 1oo c Bring the case up to proper temperature slow...

Page 78: ... surfaces thoroughly 3 Visually inspect case halves for any cracks road damage etc 4 Check all fittings not previously remov ed for signs of loosening or damage 5 If bearings have been removed check their seats for signs of damage such as the bearing spinning in the seat etc 6 Check oil delivery passages in transfer ports for signs of blockage 7 If bearings have not been removed oil them thoroughl...

Page 79: ...ft against scratches or to facilitate the operation of installation Pack the oil seal lips with grease Apply engine oil to each bearing 1 Set the crankshaft into left case half and install crankshaft installing tool 2 Hold the connecting rod at top dead center with one hand while turning the handle of the installing tool with the oiher Operate tool until crankshaft bot toms against bearing 74 ...

Page 80: ...1 Paying particular attention to the il lustration assemble the transmission shafts j 1 1st wheel gear 5 Ball 2 Distance collar 6 Drive axle 3 Washer 7 Drive axle spacer 4 Plate washer 75 8 2nd wheel gear 9 Kick idle gear 10 Circlip ...

Page 81: ...f shafts are fully seated 3 Check to see that all parts move freely prior to installing right case half Check for correct sub transmission operation and make certain that all loose shims are in place NOTE After assembly apply a liberal amount of gear oil to the gear teeth 76 5 Return spring 6 Main axle ...

Page 82: ...ion gear 15 Pawl spring 26 Plate washer 5 Shim 16 Primary driven gear comp 2 27 Drive axle spacer 6 Circlip 17 Kick gear holder 28 Bearing 7 Blind plug 18 Circlip 29 Oil seal 8 Bearing 19 Drive axle 30 Distance collar 9 Bearing cover plate 20 1st wheel gear 31 Drive sprocket 10 Panhead screw 21 2nd wheel gear 32 Lock washer 11 Primary driven gear comp 22 Distance callar 33 Lock nut 77 ...

Page 83: ...rclip 5 Spring retainer 6 7 8 9 10 6 5 Shift spring Washer Circlip Ball Shift lever 78 11 Wave washer l2 Ball Stopper spring 13 I Dust sea Panhead screw 14 15 10 18 11 20 19 16 17 18 Spring washer Stopper lever Washer turn spring 19 lever re 20 Spring hook ...

Page 84: ... or end of crankshaft After putting together both case halves check the axles shift cam and crankshaft for smooth rotation by tur ning by hand After tightening the case bolts check again for smooth rotation Interference for all bolts is about 10 mm Be careful so that all bolts are in correct position 3 Install all crankcase bolts and tighten in stages using crisscross pattern 4 After reassembly ap...

Page 85: ...ning the kick spring pull it into the crankcase 3 Hook the kick spring on to the spring stopper 4 By turning the kick crank push the kick axle into position Pump drive gear and primary drive gear By turning the oil pump gear with your fingers install the pump drive gear Do not forget to install the drive gear locating pin into the crankshaft 80 mnnmrmmm I mm ...

Page 86: ...nstall the 1st clutch assembly and 2nd clutch assembly onto the crank shaft as shown in the illustration 4 Tighten the locknut Tightening torque 28 Nm 2 8 m kg 5 Install the primary driven gear onto the main axle Crankcase cover right Install crankcase cover right 81 l 1st clutch 2 2nd clutch 1 Flywheel holding tool 2 Torque wrench 3 Clutch housing 4 Clutch weight spring ...

Page 87: ...washer 3 Spacer 4 Plate washer 1 Clutch carrier ass Y 5 g 6 Tension sprm 7 Spacer 2 a Clutch carri r ass Y 9 Tension spring g boss 10 Clutch housm l3 Spring 14 Clip 15 Plate washer 16 Belleville spring 11 Cage 17 Lock nut 12 Dowel pin 82 ...

Page 88: ...allation to avoid damaging the piston skirts against the crankcase as the cylinder is installed Note the two induction holes in the piston skirt These must be to the rear during installation Cylinder 1 Install a new cylinder base gasket 2 Install cylinder with one hand while compressing piston rings with other hand NOTE Make sure the rings are properly positioned Cylinder head Install cylinder hea...

Page 89: ...ure with bolts 2 Install three engine mounting bolts with proper tightening torque Tightening torque 18 Nm 1 8 m kg 3 Install the under cover stay with the round cut on the rear side 4 Install drive sprocket and chain NOTE lnstall chain joint in proper direction 5 Tighten drive sprocket with proper tor que Drive sprocket nut torque 55 Nm 5 5 m kg G 1 Direction of travel 84 ...

Page 90: ...odruff key Install bevelled washer lockwasher and locknut Tighten carefully to recommended tor que value Clean the magneto flywheel cam face and grease it sparingly Flywheel nut torque 50 Nm 5 0 m kg 7 Whenever the flywheel is removed igni tion timing must be re set 8 Apply a light coat of molybdenum grease to the shifter rod end 9 Install crankcase cover left 10 Install carburetor assembly and ad...

Page 91: ... 88 Description 88 CARBURETOR 89 Description 90 Disassembly 90 Troubleshooting and repair 91 Disassembling the mixing chamber 94 Reassembly and installation 95 REED VALVE ASSEMBLV 96 Description 96 Removal and assembly 97 Insulator 98 ...

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Page 93: ...ith a stiff bristle covering 3 For proper function of carburetion the filter must be in place must be clean and must be damp with oil to provide adequate protection to vital engine parts 4 For air filter maintenance see Chapter 2 1 Air cleaner case 2 Air cleaner element 3 Air cleaner cap 5 4 4 Pan head screw 5 Spring washer 88 6 Spring washer 7 Bolt ...

Page 94: ...hrottle valve Needle Clip Spring seat Throttle spring 11 17 29 28 18 19 20 21 22 23 24 14 13 12 27 Pan head screw Spring washer Air adjusting screw Air adjusting spring Throttle adjusting screw Throttle adjusting spring Starter plunger Mixing chamber top 25 Plunger spring 89 32 26 Plunger cap 27 Cable guide 28 Adjusting nut 29 Adjusting screw 30 Cable cap 31 Screw 32 Air vent pipe 33 Over flow pip...

Page 95: ...cor rectly and that all adjustments properly made Disassembly Remove the following parts as shown Pilot air screw Float Valve seat 2 Prior to carburetor disassembly study the sections on air filter spark plug Autolube and ignition timing thoroughly Each of these components works in conjunction with the carburetor to provide maximum performance and longevity Float chamber Needle valve Main nozzle ...

Page 96: ...t s 6 Never direct high pressure air into carburetor with float bowl installed Damage to floats may occur 7 Inspect the needle and seat for signs of excessive wear or attached foreign particles Replace as required Always replace inlet needle and inlet valve seat as an assembly 8 Inspect pilot air screw for signs of excessive wear or attached foreign particles Replace as required Troubleshooting an...

Page 97: ... Pilot jet Controls the ratio of fuel to air in the idle circuit Changing the jet to one with a higher number supplies more fuel to the circuit giving a richer mixture OPERATING RANGE MOST AFFECTED BY THIS JET ZERO TO 1 8 THROITLE 3 Throttle valve slide The throttle valve slide has a portion of the base cutaway to control air flowing over the main nozzle A wider angle more cutaway will create a le...

Page 98: ... giving a richer mixture OPERATING RANGE MOST AFFECTED BY THE MAIN JET 3 4 TO FULL THROTTLE NOTE Excessive changes in main jet size can affect overall performance CAUTION The fuel air mixture ratio is a gover ning factor upon engine operating temperature Any carburetor changes whatsoever must be followed by a thorough test of spark plug temperature during ac tual engine operation 6 Float level a F...

Page 99: ...t valve end e Using a vernier caliper measure the dis tance of the float arm from the top of the float chamber gasket seat gasket removed to the float arm Float level 22 0 2 5 mm NOTE The float arm should be just resting on but not depressing the spring loaded in let needle f To correct float arm height bend the tang a slight amount as required Both the right and left sides of the float arm should...

Page 100: ...e spring and plate Reassembly and installation 1 Install the float bowl and main jet banjo bolt 2 Moving to machine push needle out of seat in throttle valve slide Inspect for signs of bending scratches or wear Replace as required 3 Check needle clip position Clip position is counted starting with the first clip groove at the top of the needle 95 1 Jet needle 2 Plate 3 Spring ...

Page 101: ...After installation re adjust throttle cable and Autolube pump cable per directions in Chapter 2 REED VALVE ASSEMBLY Description 1 Yamaha has designed a unique stainless steel reed valve located between the carburetor and cylinder The valve works independently on a demand basis There s no mechanical device such as a rotary valve or piston skirt to govern its opening and closing 2 Construction of re...

Page 102: ...linder Remove assembly 2 Inspect reed petals for signs of fatigue cracks Reed petals should fit flush or nearly flush against neoprene seats If in doubt as to sealing ability apply suc tion to carburetor side of assembly Leakage should be slight to moderate 3 If disassembly of the reed valve assembly is required proceed as follows a Remove Phillips screws 2 securing stopper plate and reed to reed ...

Page 103: ...direction of reed in stallation 4 During reassembly of the reed valve assembly and manifold install new gas kets and torque the securing bolts gradually and in pattern Tighten thoroughly Insulator Check the insulator mating surfaces for war page If any warpage is evident place sand paper 60 on a surface plate and rub the mating surface against it in a circle eight movement with continuous rotation...

Page 104: ...g thickness 105 Bra drum 105 Replacing wheel bearings 105 Installing rear wheel 105 FRONT AND REAR WHEELS 105 TIRES AND TUBES 107 Removal 107 Installation 107 DRIVE CHAIN AND SPROCKETS 108 Drive sprocket 108 Driven sprocket 109 Chain inspection 109 Chain maintenance 110 FRONT FORKS 111 Disassembly 111 Inspection 113 Assembly 113 STEERING HEAD 115 Adjustment 115 Disassembly 115 Inspection 117 Remov...

Page 105: ...CK 122 Advantages of the auto cock 122 Construction 122 Position of the cock lever and fuel passages 123 Check lever position for travelling 124 Checking 124 CABLES AND FITTINGS 125 Cable maintenance 125 Throttle maintenance 127 Cable junction maintenance 127 MISCELLANEOUS CHASSIS COMPONENTS 128 ...

Page 106: ...TER 5 CHASSIS FRONT WHEEL Removal 1 Disconnect the brake cable at the front wheel backing plate 2 Disconnect the speedometer cable from the front wheel backing plate 3 Remove cotter pin from front axle 101 ...

Page 107: ... by plac ing a suitable stand under the engine Front axle Remove any corrosion from axle with emery cloth Then place it on a surface plate and check for bending If bent replace Checking the brake lining thickness 1 Measure the brake lining thickness Front brake lining thickness 4mm Replacement limit 2mm 2 Remove any glazed areas from brake shoes using coarse sand paper 102 ...

Page 108: ... tapping around the perimeter of the bearing in ner race with a soft metal drift pin and hammer Either or both bearings can be removed in this manner 3 To install the wheel bearing reverse the above sequence Be sure to grease the bearing before installation Use a socket that matches the outside race of the bearing as a tool to drive in the bear ing Installing front wheel 1 After replacing wheel an...

Page 109: ...ng 3 W hee h h ng Meter elute 32 Bus 4 Bolt She 18 geac 26T 33 011 seal 5 Sp nng w 1Q D 1 en g k shoe 4 Stop rm 6 Not 20 Brn e omplete 3 1 shaft collac Brake shoe c 35 Whee 7 Bolt 21 Wheel shaft 8 Plain washe8r 4PR 22 Camshaft g 36 Wheel shaft not g foe 400 Retorn spnn 37 22 Camshaft le e 38 Cottec pm 10 Tube 1 1 Spacer flan r2 26 5 1 li washer 12 Bearing spa 13 Bearing 104 ...

Page 110: ... front wheel section Rear brake lining thickness 4mm Replacement limit 2mm Brake drum See front wheel section Replacing wheel bearings See front wheel section Installing rear wheel 1 Install wheel and axle and tighten axle nut Install a new cotter pin Axle nut torque 60 Nm 6 0 m kg 2 Connect drive chain brake rod and ten sion bar 3 Adjust drive chain See chapter 2 4 Adjust rear brake See chapter 2...

Page 111: ...sion bar 5 Spring washer 17 Camshaft 29 Wheel shaft 41 Tension bar bolt 6 Not 18 Brake shoe complete 30 Chain puller 42 Spring washer 7 Bolt 19 Return spring 31 Plain washer 43 N t 8 Plain washer 20 Camshaft lever 32 Spring washer 44 Cotter pin 9 Tire 400 8 4PR 21 Bolt 33 N t 45 Plain washer 10 Tube 22 Plam washer 34 Wheel shaft collar 46 Tension bar clip 11 Spacer flange 23 Spring washer 35 Shaft...

Page 112: ...ion on ly the tube must be installed so the valve stem forms a specific angle with the tire rim Finally torque the eight bolts to specification and inflate tire to specified pressure I Tightening torque 15 Nm 1 5 m kg Front tire pressure cold tire Model LB50 Il AC LB80 Il AC Basic weight With oil and 80 kg 76 kg full fuel tank Maximum 140 kg 144 kg load Upto 150 kg 100 kPa load 1 00 kg cm2 1 00 ba...

Page 113: ... Remove the sprocket securing nut Remove the sprocket 3 Check sprocket wear Replace if wear decreases tooth width as shown 4 Replace if tooth wear shows a pattern such as that in the illustration or as precaution and common sense dictate 5 During reassembly make sure the lock washer splines are properly seated on the drive shaft splines Tighten securing nut to specified torque value Bend lock wash...

Page 114: ...spection 1 With the chain installed on the machine excessive wear may be roughly deter mined by attempting to pull the chain away from the rear sprocket If the chain will lift away more than one half the length of the sprocket teeth remove and inspect If any portion of the chain shows signs of damage or if either sprocket shows signs of excessive wear remove and in spect 2 Check the chain for stif...

Page 115: ...lubricant into rollers Choice of lubricant is determined by use and terrain SAE 20W or 30W oil may be used but several specialty types by accessory manufacturers such as Yamaha chain and cable lube of fer more penetration corrosion resistance for roller protection In certain areas semi drying lubricants are preferable These will resist picking up sand particles dust etc 3 Periodically remove the c...

Page 116: ...dometer cable and front brake cable removed the fork legs can be removed from the upper and lower brackets by loosening upper and lower pinch bolts 2 Remove the caps and drain the oil from both fork tubes 3 Remove the outer tube nut from outer tubes 111 ...

Page 117: ...4 Remove slide metal and inner tube from outer tube 5 Carefully pry out old seal without damageing fork tube 6 Insert new seal with open side down using large socket and soft hammer 112 ...

Page 118: ... end with a vinyl sheet to protect the oil seal lip against damage 2 Installing the front forks a Bring up the front fork to the correct position and partially tighten the underbracket mounting bolt b Pour specified amount of oil into the in ner tube through the upper end opening Use 1OW 30 SE motor oil NOTE Specialty type fork oils of quality ma nufacture such as Yamaha Fork Oil should be used if...

Page 119: ...0 11 12 Inner tube co Inner tub mplete left Slide 8 complete right metal Outer nut Oil seal complete Dust seal 114 13 14 15 Packing Guide bar 0 ring 16 Cap washer l7 Bolt 18 19 20 21 22 23 24 Underbracket Bolt complete Upper cover left Upper cover right Reflector Spring washer Plain washer ...

Page 120: ...ct electrical wires between headlight body and main wiring harness from frame 3 Disconnect any electrical wires between handlebar switches and main wiring harness in headlight body 4 Disconnect throttle cables front and rear brake at handlebars 5 Disconnect speedometer cables at instruments 6 Remove handlebars and put aside 7 Remove stem fitting bolt and crown washer 115 ...

Page 121: ...ket up into the headstock so that the loose bearings will not fall out 10 While still supporting the under bracket carefully lift off the upper bearing cover 11 Lift off the top bearing race and remove all of the ball bearings from the upper bearing assembly Ball quantity size 22 pcs 3 16 in 12 Remove bracket while being very careful not to lose any bearings from the lower assembly Ball quantity s...

Page 122: ...lace if damaged 3 Install the fork and handle crown to the under bracket If the handle crown is not aligned with the fork the under bracket is considered to be bent If bent more than 10 mm replace the bracket Removal 1 Remove races from head pipe using drift punch and hammer as shown Work the race out gradually by tapping lightly around its complete diameter 2 Remove the bearing race from the lowe...

Page 123: ... the upper assembly and arrange the balls around it Then apply more grease and set the top race into place NOTE Use medium weight wheel bearing grease of quality manufacturer preferably waterproof 4 Carefully slip the underbracket stem up into the steering head Hold the top bearing assembly in place so the stem doe s not knock any balls out of position 5 Set the upper bearing cover on and install ...

Page 124: ...on Steering fitting bolt torque 21 Nm 2 1 m kg 9 Tighten upper fork tube bolts and torque to specification Upper fork tube bolt torque 21 Nm 2 1 m kg Handlebars mounting bolt torque 21 Nm 2 1 m kg 10 Install handlebars and torque to specification 12 Nm 1 2 m kg 11 Reconnect all electrical wiring and check operation 12 Install headlight and check operation 13 Install front wheel 14 Reconnect speedo...

Page 125: ...move swing arm and replace swing arm bushing Swing arm lubrication 1 Apply grease to pivot shaft Recommended lubricant Smooth chassis lube grease 2 Wipe off excess grease Swing arm removal 1 Remove nut on swing arm pivot bolt and tap out bolt with a long aluminum or brass rod Pivot bolt torque 39 Nm 3 9 m kg 2 Tap out old bushing from each side of pivot 3 Install new bushing using a press or hand ...

Page 126: ...Rear arm Rear arm complete 6 Rear shock absorber 11 Chain case half 2 Rear arm bushing 7 Crown nut 12 Pan head screw 3 Pivot shaft 8 Washer 13 Spring washer 4 Nut 9 Cap nut 5 Guard seal 10 Washer 121 ...

Page 127: ...re pulses from the crankcase the valve automatically closes whenever the engine stops This prevents the fuel from overflowing thru the carburetor Construction 1 Diaphragm assembly The diaphragm assembly consists of diaphragm A diaphragm B and a valve The diaphragm B maintains constant fuel pressure on the diaphragm A thus diaphragm A may act only with negative pressure from intake manifold In this...

Page 128: ...nd passes through the D passage The fuel from the D passage flows through the opening of the valve to the E passage and enters the filter cup The fuel is filtered and fed to the carburetor through the G passage and the fuel pipe 2 Cock lever RES The fuel flows into the B passage and then into the carburetor through the same passages as in the case of cock lever ON 3 Cock lever PRI The fuel flows i...

Page 129: ...tank should be filled at the first opportunity 3 PRI position To fill the fuel tank of a new motorcycle or one in which the fuel tank or car buretor float chamber is empty turn the cock lever to PR I With the cock lever in PRI the fuel directly enters the filter cup from the fuel tank bypassing the rubber pipe After filling the tank turn the cock lever to ON Checking Remove the filter cup set the ...

Page 130: ...sed within this section For details see the in dividual maintenance section for which the cable is an integral part Cable routing is of paramount importance For details of cable routing see the cable routing diagrams at the general information 125 1 Remove the cable 2 Check for free movement of cable within its housing If movement is obstructed check for fraying or kinking of the cable strands If ...

Page 131: ...ew 20 Throttle wire 35 Pin 6 lever collar 21 Hexagon nut 36 Nut 7 Hexagon nut 22 Wire cylinder 37 Starter wire 8 Starter lever 23 Hexagon bolt 38 Wire harness clamp 9 Washer 24 Spring washer 39 Plug 10 Plate washer 25 Plate washer 40 Rear view mirror 11 Bolt 26 Pump wire 41 Rear brake switch 12 Front stop switch assembly 27 Throttle wire 2 13 Right lever holder assembly 28 Brake front wire 14 Righ...

Page 132: ...r Autolube control cable must be periodically maintained 1 Remove throttle cable number one from handlebar housing 2 Remove throttle cable number two from carburetor mixing chamber top 3 Remove Autolube pump cable from pump pulley Remove cable adjustor 4 Remove seat and fuel tank 5 Remove cable cylinder assembly com plete 6 Remove cylinder cap throttle cable two and Autolube pump cable 7 Wash asse...

Page 133: ...body 3 Gasket plate 1 4 Gasket plate 2 5 Fuel pipe 6 Fuel pipe 7 Clip 8 Tank fitting band 9 Fuel cock assembly 10 Packing 7 18 11 Spring plate 12 Pan head screw 13 Lever 14 Packing 15 Filter cup 128 16 Pan head screw 17 Spring washer 18 Hose 19 Pipe 20 locating damper ...

Page 134: ...Oil tank 6 4 5 1 Oil tank 2 Cap body 3 Cap gasket 4 Hose 5 Clip 6 Hose 7 Com 8 pression spring Locating damper 129 9 l ocating d 10 G amper 11 rommet Connector tube ...

Page 135: ...ONS 133 IGNITION SYSTEM 134 CIRCUIT DIAGRAM 134 TROUBLESHOOTING 135 CHARGING SYSTEM 139 CIRCUIT DIAGRAM 139 TROUBLESHOOTING 140 LIGHTING SYSTEM 143 CIRCUIT DIAGRAM 143 TROUBLESHOOTING 144 SIGNAL SYSTEM 146 CIRCUIT DIAGRAM 146 TROUBLESHOOTING 148 SIGNAL SYSTEM CHECK 150 ...

Page 136: ......

Page 137: ...y Fuse Flasher relay Ignition coil Rear brake switch CDI unit 9 10 Rectifier regulator Horn Main switch 1 V r 6 SPECIFICATIONS IGNITION COIL PRIMARY SECONDARY PICK UP COIL SOURCE COIL CHARGING COIL 132 RESISTANCE 0 32 0 48 Q 5 68 8 52 kQ 16 24 Q 264 396 Q 0 30 0 44 Q ...

Page 138: ...Check Connector leads Looseness Bend up the pin G and con nect the terminals 4 Connect Connector terminals NOTE The two terminals click together 5 Check Continuity using a pocket tester NOTE If there is no continuity clean the termi nals When checking the wire harness be sure to perform steps 1 to 3 As a quick remedy use a contact revital izer available at most part stores Check the connector with...

Page 139: ...EBB02000 IGNITION SYSTEM CIRCUIT DIAGRAM 134 ...

Page 140: ...1 Spark plug Check the spark plug condition Check the spark plug type Check the spark plug gap Refer to SPARK PLUG INSPECTION in CHAPTER 2 EBB02014 Spark plug gap 0 5 N 0 6 mm CORRECT 2 lgnition spark gap Disconnect the spark plug cap from the spark plug Connect the ignition checker G as shown Spark plug cap Turn the main switch to ON 135 5 Main switch 6 Pickup coil resistance 7 Source coil resist...

Page 141: ... to the spark plug cap Check if the spark plug cap has the specified resistance Spark plug cap resistance 5 kQ at 20 C n MEETS V SPECIFICATION EB802016 4 lgnition coil resistance Disconnect the ignition coil connector from the wire harness Connect the pocket tester Q x 1 to the ignition coil 136 MEETS SPECIFICATION IThe ignition system is not faulty OUT OF SPECIFICATION i IReplace the spark plug c...

Page 142: ...ss MEETS SPECIFICATION switch couplers Check for continuity as follows Black Red CD Black __ BIR B R Gv B OFF CHECK I ON t B Gy R BIR CD B LIW 1 CONTINUITY EB80201C 6 Pickup coil resistance Disconnect the pickup coil coupler from the wire harness Connect the pocket tester Q x 100 to the pickup coil terminal Tester lead White Green lead CD Tester lead Black terminal 137 Tester lead Ignition coil ba...

Page 143: ...al Tester lead Black Red lead CD Tester lead Black terminal Cg Check the source coil for the specified resistance Source coil resistance 264 396 Q at 20 C Black Red Black n MEET V SPECIFICATION 8 Wiring connection Check the connections on the entire igni tion system Refer to CIRCUIT DIAGRAM D CORRECT IReplace the CDI unit OUT OF SPECIFICATION i IReplace the pickup coil OUT OF SPECIFICATION i IRepl...

Page 144: ...EBB04000 CHARGING SYSTEM CIRCUIT DIAGRAM 139 ...

Page 145: ...the fuse Connect the pocket tester Q x 1 to the fuse Check the fuse for continuity EBB02012 JJ CONTINUITY 2 Battery Check the battery condition Refer to BATTERY INSPECTION CHAPTER 2 Specific gravity 1 280 at 20 C i CORRECT in 140 4 Charging coil resistance 5 Wiring connections the entire charging system NO CONTINUITY IReplace the fuse INCORRECT Add distilled water to the proper level Clean the bat...

Page 146: ... r min NOTE Use a fully charged battery EB804012 I OUTOF SPECIFICATION 4 Charging coil resistance Remove the generator cover Connect the pocket tester Q x 1 to the charging coils Tester lead White terminal CD Tester lead Black terminal Measure the charging coil resistance Charging coil resistance 0 30 0 44 Q at 20 C n MEET V SPECIFICATION jDC20V I I r MEETS SPECIFICATION IThe charging circuit is n...

Page 147: ...B804015 5 Wiring connections Check the connections of the entire charging system Refer to CIRCUIT DIAGRAM CORRECT IReplace the rectifier regulator POOR CONNECTION IProperly connect the charging system 142 ...

Page 148: ...BLUEi I I I Y R 1 f N L L___c _______ a _ Ill_______j 1 ffl l D I f B W I I B R BfR B R 1 o m W G W G WJG r O B i f I I I I 1 __ J Q fl B _ jd ijt_ _ ___ _ ftr G j G 1 ll I T h _____ J r 1 i ___ _ __ i i T i f f 1 1 _ I I _c I o Meter light High beam indicator light Light switch CDI magneto Tail brake light Dimmer switch Head light C 18 l 55 c5g c g c c j 2 z l G Cl l s Cl I m s ...

Page 149: ...ocket for conti nuity D CONTINUITY 2 Lighting coil resistance Disconnect the CDI magneto coupler from the wire harness Connect the Pocket Tester Q x 1 to the lighting coil coupler Tester Lead ry Yellow Red CD Terminal Tester Lead ry Black Terminal Measure the lighting coil resistance Lighting coil resistance 0 2 0 3 n at 20 C n MEET 7 SPECIFICATION 144 4 Dimmer switch 5 Wiring connection the entir...

Page 150: ...LO Check for continuity as follows Blue G Yellow Turn the dimmer switch to HI Check for continuity as follows Blue G Green G CONTINUITY EB805013 5 Wiring connections Check the connections of the entire lighting system Refer to CIRCUIT DIAGRAM CORRECT IReplace the rectifier regulator 145 NO CONTINUITY The light switch is faulty Replace the right handlebar switch HI LO NO CONTINUITY The dimmer switc...

Page 151: ...IGNAL SYSTEM CIRCUIT DIAGRAM r c i l II __ o t D I ______________________ I 1 1 I CJ I t I I m I 9 _______ I_____ J 146 1 _JIOll 1 I__ ______ I a 1 8 I I I I rl i Jf j1 I I I 8 1 I I 1 ____ ___ 1 I c l t l u ____ ...

Page 152: ...ator light Rear brake switch Front brake switch Tail brake light Rear turn signal Front turn signal Flasher relay Horn Horn switch Turn switch Oil level gauge Fuse Battery Audio pilot LB50 II AC For LB50 II AC ill For LB80 II AC 147 ...

Page 153: ...tool s for trouble shooting l I EB802011 1 Fuse Pocket tester 90890 03112 Remove the fuse o Connect the pocket tester Q x 1 to the fuse Check the fuses for continuity EB802012 CONTINUITY 2 Battery Check the battery condition Refer to BATTERY INSPECTION CHAPTER 2 Specific gravity 1 280 at 20 C CORRECT in 148 NO CONTINUITY IReplace the fuse INCORRECT Add distilled water to the proper level Clean the...

Page 154: ...rown B R B R G Br OFF ON E8806011 CONTINUITY 4 Wiring connections Check the connections of the entire sig nal system Refer to CIRCUIT DIAGRAM CORRECT Check the condition of each of the signal system s circuits Refer to SIGNAL SYSTEM CHECK NO CONTINUITY IReplace the main switch POOR CONNECTION IProperly connect the signal system 149 ...

Page 155: ... lead G Tester lead Frame ground Turn the main switch to ON Check the voltage 6 V of the Brown lead at the horn terminal n MEETS 7 SPECIFICATION 3 Horn Disconnect the Pink lead at the horn terminal Connect a jumper lead G to the horn ter minal and ground the jumper lead Turn the main switch to ON 150 p B OFF PUSH 2 NO CONTINUITY IReplace the left handlebar switch r r Be P 0 OUT OF SPECIFICATION i ...

Page 156: ...ON Check the voltage 6 V of the Pink lead at the horn terminal n MEETS V SPECIFICATION IAdjust or replace the horn EB806022 2 lf the brake light fails to come on 1 Bulb and bulb socket Check the bulb and bulb socket for conti nuity CONTINUITY HORN SOUNDS IThe horn is not faulty r r Br P OUT OF SPECIFICATION IReplace the horn NO CONTINUITY IReplace the bulb and or bulb socket 151 ...

Page 157: ...terminal CD Tester lead l Black terminal Turn the main switch to ON The brake lever is pulled in or the brake pedal is pressed down Check the voltage 6 V of the Green Yellow lead on the bulb socket connec tor n MEETS v SPECIFICATION IThis circuit is not faulty 152 NO CONTINUITY IReplace the brake switch OUT OF SPECIFICATION i The wiring circuit from the main switch to the bulb socket connector is ...

Page 158: ...ocolate CONTINUITY 3 Voltage Connect the pocket tester DC 20 V to the flasher relay coupler j Tester lead Brown terminal CV Tester lead Frame ground Turn the main switch to ON Check the voltage 6 V of the Brown CD lead at the flasher relay terminal MEETS SPECIFICATION 153 NO CONTINUITY IReplace the bulb and or bulb socket NO CONTINUITY IReplace the left handlebar switch OUT OF SPECIFICATION i The ...

Page 159: ...onnector At the flasher light left Tester lead Chocolate lead CD Tester lead Frame ground At the flasher light right Tester lead Dark green lead Tester H lead Frame ground Turn the main switch to ON Turn the turn switch to L or R Check the voltage 6 V of the Choco late lead or Dark green lead on the bulb socket connector n MEETS y SPECIFICATION IThis circuit is not faulty 154 D 2 OUT OF SPECIFICAT...

Page 160: ...level gauge Tester lead Brown terminal Tester lead Gray terminal Check the oil level gauge for continuity Switch position Good Bad condition condition A Upright position x 0 x 0 B Upside down 0 x x 0 position 0 Continuity X Nocontinuity n GOOD VCONDITION 3 Wiring connection Check the connections of the entire sig nal system Refer to WIRING DIAGRAM 155 NO CONTINUITY IReplace the bulb and or bulb so...

Page 161: ...CHAPTER 7 APPENDICES TROUBLESHOOTING GUIDE 158 LB50 II AC LB80 II AC WIRING DIAGRAM ...

Page 162: ......

Page 163: ...ck ignition main switch 2 Check wiring magneto coil 3 Check the pickup coil 4 Check high tension lead 5 Check spark plug 1 Use ignition checker spark gap test 2 Check spark plug 3 Check high tension lead 4 Check ignition assembly Remedy 1 Check fuel tank 2 Check petcock 3 Remove main jet check fuel flow 1 Clean fuel tank check cap vent 2 Clean petcock 3 Remove carburetor service 1 Flush fuel syste...

Page 164: ... necessary Clean qr repair as necessary Clean or repair as necessary Clean or repair as necessary Clean or repair as necessary Starter lever off Repair Level Engine Exhaust systems See No start Poor mid range and high speed performance Ignition system Possible Cause Remedy Spark plug incorrect Clean and gap or change plug if necessary Ignition timing incorrect Check the ignition system Air Fuel sy...

Page 165: ... I I L ____ L Blue Y Yellow O Orange B R Black Red P Pink B W Black White R Red Br W Brown White Sb Sky blue w White G Y Green Yellow L W Blue White I I I I I Dg E ml p J y i m i ___ J B I I I I I I I I I I I I I I I I I WIG White Green Y R Yellow Red Y W Yellow White 1 _ I I G Y j Main switch Oil level indicator light Meter light High beam indicator light Right handlebar switch Light switch QI Re...

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Yamaha LB50IIAC, Service Manual

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