HYOSUNG RX 125 Service Manual
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HYOSUNG RX 125 Service Manual

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RX
125
HYOSUNG MOTORS & MACHINERY INC.
SERVICE MANUAL
99000-97100

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  • Page 1 HYOSUNG MOTORS & MACHINERY INC. SERVICE MANUAL 99000-97100...
  • Page 2 HYOSUNG vehicles. Without such knowledge and skills, you should not attempt servicing by relying on this manual only. Instead, please contact your nearby authorized HYOSUNG motorcycle dealer. HYOSUNG MOTORS & MACHINERY INC. � COPYRIGHT HYOSUNG MOTORS & MACHINERY INC. 1999...
  • Page 3 HOW TO USE THIS MANUAL TO LOCATE WHAT YOU ARE LOOKING FOR: 1. The text of this manual is divided into sections. 2. As the title of these sections are listed on the previous page as GROUP INDEX, select the section where what you are looking for belong.
  • Page 4 SYMBOL Listed in the table below are the symbols indicating instructions and other information necessary for servicing and meaning associated with them respectively. SYMBOL DEFINITION SYMBOL DEFINITION Torque control required. Data beside it indicates Apply THREAD LOCK “1324” . specified torque. Apply oil.

  • Page 6: Table Of Contents

    GENERAL INFORMATION CONTENTS INFORMATION LABELS GENERAL PRECAUTIONS SERIAL NUMBER LOCATION FUEL AND OIL RECOMMENDATIONS BREAK-IN PROCEDURES SPECIFICATIONS...

  • Page 7: General Precautions

    1-1 GENERAL INFORMATION WARNING / CAUTION / NOTE Please read this manual and follow its instructions carefully. To emphasize special information, the symbol and the words WARNING, CAUTION and NOTE have special meanings. Pay special attention to the messages highlighted by these signal words. WARNING Indicates a potential hazard that could result in death or injury.
  • Page 8 GENERAL INFORMATION 1-2 CAUTION ● If parts replacement is necessary, replace the parts with HYOSUNG Genuine Parts or their equivalent. ● When removing parts that are to be reused, keep them arranged in an orderly manner so that they may be reinstalled in the proper order and orientation.

  • Page 9: Serial Number Location

    1-3 GENERAL INFORMATION HYOSUNG RX125 RIGHT SIDE LEFT SIDE * Difference between photographs and actual motorcycles depends on the markets. SERIAL NUMBER LOCATION The frame serial number or V.I.N. (Vehicle Identification Number) is stamped on the right side of the steering head pipe.

  • Page 10: Break-In Procedures

    GENERAL INFORMATION 1-4 BRAKE FLUID Specification and classification: SAE J1703, DOT3 or DOT4 WARNING Since the brake system of this motorcycle is filled with a glycol-based brake fluid by the manufacturer, do not use or mix different types of fluid such as silicone-based and petroleum-based fluid for refilling the system, otherwise serious damage will result.

  • Page 11: Specifications

    1-5 GENERAL INFORMATION SPECIFICATIONS DIMENSIONS AND DRY MASS Overall length ………………………………………………………2,190 mm(86.2 in) Overall width …………………………………………………………800 mm(31.5 in) Overall height ………………………………………………………1,160 mm(45.7 in) Wheelbase ……………………………………………………………1,425 mm(56.1 in) Ground clearance …………………………………………………295 mm(11.6 in) Dry mass ……………………………………………………………125 kg(276 lbs) ENGINE Type ……………………………………………………………………Four-stroke, SOHC Number of cylinder …………………………………………………1 Bore ……………………………………………………………………57 mm(2.24 in) Stroke …………………………………………………………………48.8 mm(1.92 in)
  • Page 12 GENERAL INFORMATION 1-6 ELECTRICAL Ignition type …………………………………………………………Battery Ignition (CDI) Ignition timing ………………………………………………………15°B.T.D.C.at 2,250 rpm and 35°B.T.D.C.at 4,000 rpm Spark plug ……………………………………………………………C8EH-9 Battery…………………………………………………………………12V 6Ah Fuse ……………………………………………………………………15 A Headlight ……………………………………………………………12V 35/35 W×2 Turn signal light ……………………………………………………12V 1.7 W×2 Tail/Brake light ………………………………………………………12V 21/5 W×2 Speedometer light …………………………………………………14V 3.4 W High beam indicator light …………………………………………12V 1.7 W Turn signal indicator light …………………………………………12V 1.7 W...
  • Page 13 PERIODIC MAINTENANCE CONTENTS PERIODIC MAINTENANCE SCHEDULE 2- 1 MAINTENANCE PROCEDURES 2- 3 BATTERY 2- 3 CYLINDER HEAD NUTS, CYLINDER NUTS, EXHAUST PIPE BOLT AND NUTS 2- 3 AIR CLEANER ELEMENT 2- 4 VALVE CLEARANCE 2- 5 COMPRESSION PRESSURE 2- 6 SPARK PLUG 2- 6 FUEL LINE...

  • Page 14: Periodic Maintenance Schedule

    2-1 PERIODIC MAINTENANCE PERIODIC MAINTENANCE SCHEDULE The chart below lists the recommended intervals for all the required periodic service work necessary to keep the motorcycle operating at peak performance and economy. NOTE: More frequent servicing should be performed on motorcycles that are used under severe conditions. PERIODIC MAINTENANCE CHART ENGINE Interval...
  • Page 15 PERIODIC MAINTENANCE 2-2 LUBRICATION CHART The maintenance schedule, which follows, is based on this philosophy. It is timed by odometer indication, and is calculated to achieve the ultimate goal of motorcycle maintenance in the most economical manner. Interval Interval and Every 4,000 km Every 8,000 km Item Throttle cable...

  • Page 16: Engine

    2-3 PERIODIC MAINTENANCE MAINTENANCE PROCEDURE This section describes the service procedures for each section of the periodic maintenance. BATTERY NOTE: Inspect Initial 1,000 km and Every 4,000 km. ● Remove the seat for measure of battery voltage. ● Using pocket tester, measure the battery voltage. If the tester reading is less than 12.8V, recharge battery by a battery charger.

  • Page 17: Air Cleaner Element

    PERIODIC MAINTENANCE 2-4 Cylinder head nut (12mm) : 25~29 N∙m (2.5~2.9 kg∙m) Cylinder base nut (10mm) : 6~8 N∙m ② (0.6~0.8 kg∙m) ● When installing cylinder head cover, the rubber packing is reached the mating surface of cylin der head cover. ③...

  • Page 18: Valve Clearance

    : do not twist or wring the element or it will develop tears. ● Immerse the element in Hyosung genuine oil, and squeeze the oil out of the element leaving it slightly wet with oil.

  • Page 19: Compression Pressure

    PERIODIC MAINTENANCE 2-6 ● Remove spark plug, cylinder head cover ①, and valve timing inspection plug ②. ● Remove the magneto cover cap ③ and rotate the magneto rotor with the 14 mm box wrench to set the piston at (TDC) of the compression stroke.

  • Page 20: Fuel Line

    2-7 PERIODIC MAINTENANCE standard plug is apt to get wet, a hotter plug should be used. If the standard plug is apt to overheat (porcelain is whitish in appearance), replace with a colder one. TYPE SPARK PLUG SPECIFICATION Hot type N.G.K C7EH-9 Standard N.G.K C8EH-9...

  • Page 21: Engine Oil Filter

    PERIODIC MAINTENANCE 2-8 ENGINE OIL FILTER NOTE: Replace lnitial 1,000 km and Every 4,000 km. Replace the filter in the following manner. ● Drain engine oil by removing the drain plug. ● Remove the three screws securing the filter cap. ●...

  • Page 22: Carburetor

    2-9 PERIODIC MAINTENANCE CARBURETOR NOTE: Inspect lnitial 1,000 km and Every 4,000 km. IDLING ADJUSTMENT ① NOTE: Make this adjustment when the engine is hot. ● Start up the engine and set its speed at any- where between 1,400 and 1,500 rpm by turning throttle stop screw ①.

  • Page 23: Drive Chain

    PERIODIC MAINTENANCE 2-10 DRIVE CHAIN NOTE: Inspect and Clean Every 1,000 km. Visually inspect the drive chain for the below listed possible abnormality. (Lift the rear wheel by plac- ing the jack or block, and turn the rear wheel slowly by hand, with the transmission in NEUTRAL.) Inspect for : 1.

  • Page 24: Brakes

    Specification DOT3, DOT4 and Classification or SAE J1703 HYOSUNG Brake fluid : 99000-07100 WARNING The brake system of this motorcycle is filled with a glycol-based brake fluid. Do not use or mix different types of fluid such as silicone-...
  • Page 25 PERIODIC MAINTENANCE 2-12 AIR BLEEDING THE BRAKE FLUID CIRCUIT Air trapped in the fluid circuit acts like a cushion to absorb a large proportion of the pressure devel- oped by the master cylinder and thus interferes with the full braking performance of the caliper b r a k e .

  • Page 26: Tires

    2-13 PERIODIC MAINTENANCE REAR BRAKE This is effected by turning the brake pedal stopper. Be sure to tighten the lock nut securely after set- ting the bolt. After adjusting the rear brake height, adjust the brake pedal traval, First set the pedal at position ①...

  • Page 27: Steering

    PERIODIC MAINTENANCE 2-14 STEERING NOTE: Inspect lnitial 1,000 km and Every 4,000 km. ③ ② Steering stem bearings should be adjusted properly for smooth turning of the handlebars and safe running. steering which is too stiff prevents smooth move- ment of handlebars. ①...
  • Page 28 2-15 PERIODIC MAINTENANCE CHASSIS AND ENGINE MOUNTING BOLTS AND NUTS NOTE: Inspect lnitial 1,000 km and Every 4,000 km. The nuts and bolts listed are important parts, and they must be in good condition for safety. They must be retightened, as necessary, to the specified torque with a torque wrench. Front axle bolt(①) : 50~80 N∙m (5.0~8.0 kg∙m) Caliper mounting bolt (②) : 18~28 N∙m (1.8~2.8 kg∙m) Brake hose union bolt(③) : 20~25 N∙m (2.0~2.5 kg∙m)
  • Page 29 PERIODIC MAINTENANCE 2-16 ⑧ ⑦ ⑥ ⑩ ⑨...
  • Page 30 ENGINE CONTENTS COMPRESSION PRESSURE AND OIL PRESSURE 3- 1 ENGINE REMOVE AND REMOUNTING 3- 2 UPPER END COMPONENTS DISASSEMBLY 3- 6 UPPER END COMPONENTS INSPECTION AND SERVICING 3-10 UPPER END COMPONENTS REASSEMBLY 3-20 LEFT ENGINE DISASSEMBLY 3-26 RIGHT ENGINE DISASSEMBLY 3-28 LOWER END COMPONENTS DISASSEMBLY 3-30...

  • Page 31: Compression Pressure And Oil Pressure

    3-1 ENGINE COMPRESSION PRESSURE OIL PRESSURE Install the oil pressure gauge in the position shown AND OIL PRESSURE in the illustration. Warm up the engine as follows. COMEPRESSION PRESSURE ● Summer approx. 10 min. at 2,000 rpm. ● Winter approx. 20 min. at 2,000 rpm. CAUTION After the warming up operation, increase the engine speed to 3,000 rpm, and read the oil pres-...

  • Page 32: Engine Remove And Remounting

    ENGINE 3-2 ENGINE REMOVAL AND REMOUNTING ENGINE REMOVAL Before taking the engine out of the frame, thor- oughly clean the engine with a suitable cleaner. The procedure of engine removal is sequentially explained in the following steps. ● Take off the seat by loose two volts below seat. ●...
  • Page 33 3-3 ENGINE ● Take off the clutch cable by removing the clutch lever bolts and adjuster lock nut. ● Disconnect the lead wire of starter motor. ● Take off the magneto. ● Take off the spark plug cap.
  • Page 34 ENGINE 3-4 ● Take off the breather hose. ● Loosen the two clamp screws, bolt and take off the carburetor. ● Remove the engine sprocket cover. ● Take off the drive chain by removing the clip.
  • Page 35 3-5 ENGINE ● Disconnect the ground wire from the crankcase. ● Take off the gear shift lever by removing the bolt. ● Remove the exhaust pipe nuts and muffler mounting bolt, then take off the muffler. ● Take out only one third of shaft after remove the swing arm pivot nut.

  • Page 36: Upper End Components Disassembly

    ENGINE 3-6 ENGINE REMOUNTING ● After remounting the engine, following adjust- ments are necessary. The engine can be mounted in the reverse order of removal. � Throttle cable (Page : 2-9) ● Temporarily fasten the engine mounting bracket � Clutch cable (Page : 2-9) before inserting the engine mounting bolts.
  • Page 37 3-7 ENGINE ● Remove the cam chain tensioner. ● Loosen the cylinder head cover bolts and detach the head cover. ● Loosen the camshaft holder lock nuts diagonal- ly, then detach the camshaft holder. ● Remove the camshaft center bolt. CAUTION This is a left-hand thread nut.
  • Page 38 ENGINE 3-8 ● Remove the camshaft ①, cam sprocket ② and C-ring ③ CAUTION ① Do not drop the camshaft drive chain, key and sprocket into the crankcase. ③ ② CAMSHAFT HOLDER ● Take off the rocker arm spring ⑤ from the dowel pin ④.
  • Page 39 3-9 ENGINE CYLINDER HEAD ● Loosen the cylinder head nuts, then detach the cylinder head. CAUTION If it is difficult to remove the cylinder head, gently pry it off while tapping the finless portion of the cylinder head with a plastic hammer. Be careful not to break the fin.
  • Page 40 ENGINE 3-10 CYLINDER ● Remove the cylinder base nuts and cylinder. CAUTION If tapping with the plastic hammer is necessary, do not break the fins. PISTON ● Place a clean rag over the cylinder base to pre- vent the piston pin circlip from dropping into the crankcase and then, remove the piston pin cir- clip with the long-nose pliers.

  • Page 41: Upper End Components Inspection And Servicing

    3-11 ENGINE UPPER END COMPONENTS INSPECTION AND SERVICING CAMSHAFT HOLDER DISTORTION After removing the oil from the fitting surface of the camshaft holder, place the camshaft holder on a surface plate and check for distortion with a thick- ness gauge. Check points are shown in Fig. Camshaft holder distortion Service limit 0.05 mm ●...
  • Page 42 ENGINE 3-12 CAMSHAFT CAM WEAR Worn-down cams are often the cause of mistimed valve operation resulting in reduced output power. The limit of cam wear is specified for both intake and exhaust cams in terms of cam height �, which is to be measured with a micrometer.
  • Page 43 3-13 ENGINE VALVE HEAD RADIAL RUNOUT Place the dial gauge at right angles to the valve head, and measure the valve head radial runout. If it measures more than limit, replace the valve. Valve head radial runout Service limit 0.03 mm VALVE GUIDE-VALVE STEM CLEARANCE Measure the clearance in two directions, “X”and “Y”...
  • Page 44 ENGINE 3-14 VALVE GUIDE INSTALLATION ② ① ● Re-finish the vave guide holes in cylinder head with a 10.5 mm reamer ① and handle ②. 10.5 mm Reamer : 09916H34575 Handle : 09916-34541 ● Fit a ring to each valve guide. Be sure to use new rings and valve guides.
  • Page 45 3-15 ENGINE ● Lubricate each seal, and drive them into posi- tion with the valve stem seal installer ①. ① CAUTION Do not reuse the oil seals. Valve guide installer and stem seal installer : 09916-44910 VALVE SEAT WIDTH ● Coat the valve seat with prussian blue uniformly. Fit the valve and tap the coated seat with the valve face in a rotating manner, in order to obtain a clear impression of the seating...
  • Page 46 ENGINE 3-16 1. Insert with a slight rotation, the solid pilot that gives a snug fit. The shoulder on the pilot should be about 10㎜ from the valve guide. 2. Using the 45�cutter, descale and cleanup the seat with one or two turns. 3.
  • Page 47 If the limit indicated below is exceed- ed by the free length reading or if the measured force does not fall within the range specified, replace with a HYOSUNG spring as a set. Valve spring free length Service limit Valve spring free length IN.
  • Page 48 ENGINE 3-18 PISTON-CYLINDER CLEARANCE As a result of the above measurement, if the piston to cylinder clearance exceeds the limit shown in the table below, overhaul the cylinder and use an over- size piston, or replace both cylinder and piston. Service limit 0.120 mm Piston cylinder clearance PISTON RING-GROOVE CLEARANCE...
  • Page 49 3-19 ENGINE OVERSIZE RINGS ● Oversize piston rings The following two types of oversize piston rings are used. They bear the following identification numbers. Oversize piston ring 0.5 mm 1.0 mm ● Oversize oil rings The following two types of oversize oil ring are used.

  • Page 50: Upper End Components Reassembly

    ENGINE 3-20 UPPER END COMPONENTS REASSEMBLY OIL RING Install spacer ① into the bottom ring groove first. Oil ring Then install both side rails ②, one on each side of the spacer. The spacer and side rails do not have a specific top or bottom when they are new. When reassembling used parts, install them in their original place and direction.
  • Page 51 3-21 ENGINE PISTON The following are reminders for piston installation: ● Rub a small quantity of HYOSUNG MOLY PASTE onto the piston pin. ● Place a clean rag over the cylinder base to pre- vent piston pin circlip from dropping into crankcase, and then fit the piston pin circlip with long-nose pliers.
  • Page 52 ENGINE 3-22 VALVE AND SPRING ● Insert the valves, with their stems coated with (HYOSUNG MOLY PASTE) all around and along the full stem length without any break. Similarly oil the lip of the stem seal. HYOSUNG MOLY PASTE CAUTION When inserting each valve, take care not to damage the lip of the stem seal.
  • Page 53 3-23 ENGINE ● Fit the cylinder head. ● Tighten the cylinder base nuts ①, ②. Cylinder base nut : 6~8 N∙m (0.6~0.8 kg∙m) ② CAUTION ① When mounting the cylinder, after attaching camshaft drive chain, keep the camshaft drive chain taut. The camshaft drive chain must not be caught between cam drive chain sprocket and crankcase when crankshaft is rotated.
  • Page 54 ● Apply HYOSUNG MOLY PASTE properly to the camshaft bearing and camshaft face. CAMSHAFT HOLD ② ● Apply HYOSUNG MOLY PASTE to the rocker arm ④ shafts ⑤, then inserting the camshaft hold. ● Install the rocker arm spring ③, rocker arm ④...
  • Page 55 3-25 ENGINE ● Fit the two dowel pins and install the camshaft holder ①. ① ● Tighten the camshaft holder nuts diagonally to the specified. Camshaft holder nut : 25~35 N∙m (2.5~3.5 kg∙m) CHAIN TENSIONER ● Mount the tensioner body on the cylinder. ●...

  • Page 56: Left Engine Disassembly

    ENGINE 3-26 VALVE CLEARANCE ● After tightening the camshaft holder lock nuts, check and adjust the valve clearance. Valve clearance specifications IN and EX. valve clearance 0.08~0.13 mm CAUTION Valve clearance is to be checked when the engine is cold. Both the intake and exhaust valves must be checked and adjusted when the piston is at Top- Dead-Center(TDC) of the compression stroke.
  • Page 57 3-27 ENGINE ● Remove the starter clutch gear. ● Remove the starter screw by using the impact drive and detach the stator. ● Remove the roller①, spring ② and push piece ③ from the stater clutch. ③ ① ② ● Clamp the rotor with a vise taking care not to damage it and remove the three bolts using the 5 mm “T”type hexagon wrench.

  • Page 58: Right Engine Disassembly

    ENGINE 3-28 GEAR POSITION SWITCH ● Remove the gear position indicator switch by removing the screws. CAUTION When removing gear position switch, do not lose the O-ring, switch contact and its spring. RIGHT ENGINE DISASSEMBLY ENGINE SPROCKET ● Flatten the lock washer, then remove the sprocket nut by using the special tool.
  • Page 59 3-29 ENGINE ● Remove the clutch spring mounting bolts diago- nally while holding the primary driven gear, and remove the clutch pressure plate. ● After removal of clutch drive and driven plates, flatten the lock washer and remove the clutch sleeve hub by using the special tool.

  • Page 60: Gear Shifter

    ENGINE 3-30 OIL PUMP ● Remove the oil pump mounting screws and take off the oil pump body. GEAR SHIFTER ① ● To remove the cam driven gear, first remove the ② gear shifting shaft, and loosen the pawl lifter ③...
  • Page 61 3-31 ENGINE ● Remove the sump filter. ● Remove the crankcase securing bolts. ● Separate the crankcase into 2 part, right and left with the crankcase separater. Crankcase separater : 09920-13120 ● Fit the crankcase separater so that the tool plate is parallel with the end face of the crankcase.
  • Page 62 ENGINE 3-32 ● Draw out the gear shifting fork shafts and take off the forks. ● Remove the clusters of gears and the gear shifting cam. KICK STARTER SHAFT ● Remove the circlip, spring guide and return spring. ● Then, pull out the kick starter shaft from the other side.

  • Page 63: Lower End Components Disassembly

    3-33 ENGINE OIL SEAL AND BEARING ● Remove the retainer, oil seals and bearings. Oil seal remover : 09913-50121 LOWER END COMPONENTS INSPECTION AND SERVICING CONROD DEFLECTION AND CONROD BIG END SIDE CLEARANCE Wear on the big end of the conrod can be estimat- ed by checking the movement of the samll end of the rod.
  • Page 64 ENGINE 3-34 Push the big end of the conrod to one side and measure its side clearance with a thickness gauge. Clearance standard on Service limit on big end big end of conrod of conrod 0.10~0.45 mm 1.00 mm Thickness gauge : 09900-20803 When the limit is exceeded, replace crankshaft assem- bly or reduce the deflection and the side clearance to within the limit by replacing the worn parts-conrod, big...
  • Page 65 3-35 ENGINE CLUTCH DRIVEN PLATE Measure each of the driven plate for distortion with a thickness gauge. Replace the driven plates which. Thickness gauge : 09900-20803 Distortion of clutch Service limit driven plate 0.1 mm Checking distortion CLUTCH SPRING FREE LENGTH Measure the free length of each coil spring with a vernier calipers, and determine the elastic strength of each.

  • Page 66: Primary Driven Gear

    ENGINE 3-36 Shifting fork to groove Standard Serivice limit clearance 0.10~0.30 mm 0.50 mm Standard Shifting fork NO.1 & NO.2 5.0~5.1 mm groove width NO.3 5.5~5.6 mm Standard Shifting fork NO.1 & NO.2 4.8~4.9 mm thickness Checking groove width NO.3 5.3~5.4 mm Checking thickness PRIMARY DRIVEN GEAR...
  • Page 67 3-37 ENGINE CRANKCASE BEARING Play Inspect the play of crankcase bearing inner race by hand while fixing it in the case. Play Rotate the inner race by hand to inspect for an abnormal noise and a smooth rotation. Replace the bearing if there is something unusual.

  • Page 68: Lower End Components Reassembly

    ENGINE 3-38 LOWER END COMPONENTS REASSEMBLY CRANKSHAFT ● Inspect the between the webs referring to the ● When mounting the crankshaft in the crankcase, below figure when rebuilding the crankshaft. it is necessary to pull its left end into the crankcase.
  • Page 69 3-39 ENGINE CAUTION Never fit the crankshaft into the crankcase by striking it with a plastic hammer. A l w a y s u s e t h e s p e c i a l t o o l , o t h e r w i s e crankshaft alignment accuracy will be affected.
  • Page 70 ENGINE 3-40 Washers and circlips thickness. � 1.2 mm � 1.0 mm � 1.0 mm � 0.5 mm � 1.0 mm NOTE: When reassembling the bearing retainer, apply a small quantity of THREAD LOCK “1324”to the threaded parts of the bearing retainer screws. In reassembling the transmission, attention must be given to the locations and positions of washers and circlips.

  • Page 71: Gear Shifting Cam And Fork

    3-41 ENGINE GEAR SHIFTING CAM AND FORK ● Fit the gear shifting cam on the crankcase. Position the cam as shown in Fig. So that the gear shifting fork can be installed easily.

  • Page 72: Kick Starter

    ENGINE 3-42 CAUTION Two kinds of the gear shifting forks, ① and ②, are used. They resembles each other very closely in external appearance and configura- tion. Carefully examine the illustration for correct ② ① installing positions and directions. ● After the cam stopper and gear shifting forks have been fitted, hook the cam stopper spring into the crankcase.
  • Page 73 3-43 ENGINE ● When fitting the kick starter to the shaft, be sure to align the punched marks.. ● ● ● Fit the spring and washer on the shaft. Then, insert the kick starter shaft into the crankcase. Engage the pawl ② of kick starter guide ①. ①...

  • Page 74: Right Engine Reassembly

    ENGINE 3-44 ● After the crankcase bolts have been tightened, check if the driveshaft and countershaft rotate smoothly. ● If a large resistance is felt to rotation, try to free the shafts by tapping the driveshaft or counter- shaft with a plastic hammer as shown in Fig. RIGHT ENGINE REASSEMBLY CLUTCH KICK START DRIVE GEAR AND IDLE GEAR...
  • Page 75 3-45 ENGINE GAER SHIFTING SHAFT Install the gear shifting shaft. Match the center teeth of the gear on the shifting shaft with the cen- ter teeth on the shifting driven gear as shown. CAUTION After the cam driven gear, cam guide, gear shifting shaft and neutral cam stopper have been fitted, confirm that gear change is normal while turning, the countshaft and driveshaft.
  • Page 76 ENGINE 3-46 CAUTION After mounting the oil pump in the crankcase, rotate the pump gear by hand to see if it turns smoothy. Bend up ● After checking the oil pump, install the oil pump drive gear, lock washer and nut, tighten it with a torque wrench to the specified torque and bend up to the washer.
  • Page 77 3-47 ENGINE ● Install the clutch camshaft by positioning the face to right side. ● Install the oill seal by using the 17 mm socket. ● Tighten the oil seal retainer screw. Assemble the clutch, in the reverse order of disas- sembly.

  • Page 78: Left Engine Reassembly

    ENGINE 3-48 ● Tighten the clutch spring bolts diagonally. Clutch release screw adjustment ● Loosen the lock nut, and turn in the release screw to feel high resistance. ● From that position, turn out the release screw 1/4-1/2 turn, and tighten the lock nut. OIL SUMP FILTER ●...
  • Page 79 3-49 ENGINE STATOR Apply a small quantity of THREAD LOCK “1324”to the threaded parts of screws. Thread Lock “1324” STARTER CLUTCH Locate the shim ① to the proper position ① ● Apply THREAD LOCK “1324”to the bolts and tighten with the specified torque. Thread Lock “1324”...
  • Page 80 ENGINE 3-50 ● Tighten the magneto rotor nut to the specified torque. Thread Lock “1324” Rotor holder : 09930-40113 Rotor holder : 09930-44511 Magneto rotor nut : 56~60 N∙m (5.6~6.0 kg∙m) STARTER IDLE GEAR AND MOTOR ● Install the starter idle gear. ●...
  • Page 81 3-51 ENGINE ● Tighten the engine sprocket nut to the specified torque and bend up the washer. Rotor holder : 09930-40113 Engine sprocket nut : 80~100 N∙m (8.0~10.0 kg∙m) GEAR POSITION SWITCH ● Install the gear position switch.

  • Page 82: Fuel System

    FUEL SYSTEM CONTENTS FUEL COCK 4- 1 CARBURETOR 4- 2 THROTTLE VALVE 4- 3 CARBURETOR 4- 4 ACCELERATOR PUMP ADJUSTMENT 4- 8 PILOT SCREW ADJUSTMENT 4- 9 OIL COOLER 4-10 LUBRICATION SYSTEM 4-11...

  • Page 83: Fuel Cock

    4-1 FUEL SYSTEM FUEL COCK CLEANING Rust from the fuel tank tends to build up the filter, which, when the filter has been neglected for a long period, inhibits the flow of fuel. Remove the rust from the filter using compressed air.

  • Page 84: Carburetor

    FUEL SYSTEM 4-2 CARBURETOR � � � � � ITEM SPECIFICATION ITEM SPECIFICATION Carburetor type PD 18 F Needle jet(N.J) � AIFC-2nd Bore size ф 24 Pilot jet(P.J) � # 38 I.D. NO. HG58 By pass(B.P.) 2.9, ф 1.0, ф 0.9 Idel rpm 1,450±100 rpm Pilot air jet(P.A.J)

  • Page 85: Throttle Valve

    4-3 FUEL SYSTEM THROTTLE VALVE DISASSEMBLY ● Disconnect the seat and fuel tank. (See page 3-2) ● Looen the carburetor top ① and disconnect the throttle valve. ① ● Remove the throttle cable from the throttle valve ② and disconnect the throttle cable. ②...

  • Page 86: Carburetor

    FUEL SYSTEM 4-4 ● Install the jet needle and retainer clip into the throttle valve. Leaner ※ Needle clip standard position : 3rd groove ↑ ● Install the carburetor top and spring into the (Standard) throttle cable. ↓ ● Install the throttle cable into the throttle valve. Richer REASSEMBLY Following adjustments and inspection are necessary...
  • Page 87 4-5 FUEL SYSTEM ● Loosen the carburetor nut and clamp screw. ● Remove the carburetor. DISASSEMBLY ● Disconnect the fuel tube and drain tube. ACCELERATOR PUMP ● Loosen the screws and disconnect the pump cover. ● Disconnect the spring. ● Inspect the accelerator pump load damage of the diaphragm.
  • Page 88 FUEL SYSTEM 4-6 ● Set up the diaphragm and the float chamber. ● Install the spring in the diaphragm and install the cover in the float chamber. ● Adjust the accelerator pump. FLOAT AND NEEDLE VALVE ● Loosen the screws and remove the float chamber. ●...
  • Page 89 4-7 FUEL SYSTEM JETS ● Disconnect the main jet ①, needle jet holder ② ① and needle jet. ② ● Disconnect the slow jet ③. ③ ● Disconnect the pilot screw after record the revolutions until tighten completely. CAUTION Do not tighten the pilot screw by force, otherwise can be damaged of the seat.

  • Page 90: Accelerator Pump Adjustment

    FUEL SYSTEM 4-8 ● Install the needle valve ①, float ② float arm pin ③. ② ① ③ FLOAT ADJUSTMENT ● To check the float height, invert the carburetor body, holding the float arm pin so that the pin will not slip off.

  • Page 91: Pilot Screw Adjustment

    4-9 FUEL SYSTEM REASSEMBLY ● Install the fuel tube and drain tube. ● Replace a new O-ring at the carburetor outlet side. Install the carburetor between the intake pipe and air cleaner outlet tube, tighten the carburetor lock nut and clamp screw. ●...

  • Page 92: Oil Cooler

    FUEL SYSTEM 4-10 OIL COOLER DISASSEMBLY ● Remove the oil cooler cover. NOTE: Draw out and push for face of the spring seat. ● Remove the screws. ● Remove the union bolts and detach the oil cooler. NOTE: When reassemble after remove the union bolt, do not remove except special case that fold of the hose, the others, are affected according to assemble angle.

  • Page 93: Lubrication System

    4-11 FUEL SYSTEM LUBRICATION SYSTEM CAMSHAFT JOURNAL CONROD SMALL END AND CAM FACE OIL HOSE CAM CHAIN CYLINDER WALL ROCKER ARM SHAFT ▶ OIL COOLER CONROD BIG OIL HOSE END BEARING CLUTCH RELEASE CAM COUNTERSHAFT BEARING DRIVESHAFT OIL FILTER BEARING COUNTERSHAFT BY-PASS AND GEARS...
  • Page 94 FUEL SYSTEM 4-12 Oil cooler Piston Cylinder Start motor Cylinder head Crankcase Transmission...
  • Page 95 ELECTRICAL SYSTEM 5-1 ELECTRICAL SYSTEM CONTENTS IGNITION SYSTEM 5- 1 CHARGING SYSTEM 5- 5 STARTER SYSTEM 5- 9 LAMP 5-12 SWITCHES 5-13 BATTERY 5-14...

  • Page 96: 5-1 Electrical System

    5-1 ELECTRICAL SYSTEM IGNITION SYSTEM RX 125 is started as the battery discharged ignition system without a contact point. The battery ignition system is composed a rotor tip, the D.C CDI, the igniton coil and battery. Ignite after permit signal at ignition timing of pick-up as electric energy of this battery, occur the 1st electric current.
  • Page 97 ELECTRICAL SYSTEM 5-2 INSPECTION MAGNETO Using the pocket tester, measure the resistance between the lead wires in the following table. Pick-up coil G-L Approx 90~110 Ϊ Charging coil Y-Y Approx 0.6~0.9 Ϊ Pocket Tester : 09900-25002 CAUTION When mounting the stator on the magneto cover, apply a small quantity of THREAD LOCK “1324”...
  • Page 98 5-3 ELECTRICAL SYSTEM � Probe of tester ⑤ ⑥ ④ － ∞ ∞ 5~500 10~1,000 ∞ 5~500 － ∞ 1~50 1~100 ∞ ∞ ∞ － ∞ ∞ ∞ 5~500 ∞ ∞ － 1~100 ∞ ① ∞ ∞ ∞ ∞ － ∞...
  • Page 99 ELECTRICAL SYSTEM 5-4 IGNITION COIL (Checking with Pocket Tester) ● A pocket tester or an ohm meter may be used, instead of the electro tester. In either case, the ignition coil is to be checked for continuity in both primary and secondary windings. Exact ohmic readings are not necessary, but, if the windings are in sound condition, their continuity will be noted with these approximate ohmic values.

  • Page 100: Charging System

    5-5 ELECTRICAL SYSTEM CHARGING SYSTEM The circuit of the charging system is indicated in figure, which is composed of and the AC generator, regulator / rectifier unit and battery. The AC current generated from the AC generator is converted by the rectifier and is turned into the DC current, then it charges the battery.
  • Page 101 ELECTRICAL SYSTEM 5-6 When the engine rpm become higher, the generated voltage of the AC generator also becomes higher and the voltage between points � and � of the regulator according becomes high, and when it reaches the adjusted volt- age of the control unit, consequently the control unit becomes “ON”condition.
  • Page 102 5-7 ELECTRICAL SYSTEM INSPECTION CHARGING OUTPUT CHECK Start the engine and keep it running at 5,000 rpm. Using the pocket tester, measure the DC voltage between the battery terminal � and �. If the tester reads under 13.5 V or over 16.0 V, check the AC generator no-load performance and regulator / rectifier.
  • Page 103 ELECTRICAL SYSTEM 5-8 REGULATOR / RECTIFIER Using the pocket tester (× 1 Ϊ range), measure the resistance between the lead wires in the following table. If the resistance checked is incorrect, replace the regulator / rectifier. Pocket tester : 09900-25002 Unit : Ϊ...

  • Page 104: Starter System

    5-9 ELECTRICAL SYSTEM STARTER SYSTEM The starter system is shown in the diagram below : namely, the starter motor, relay, IG switch, starter button and battery. Depressing the starter button (on the right handlebar switch box) energizes the relay, causing the contact points to close which connects the starter motor to the battery.
  • Page 105 ELECTRICAL SYSTEM 5-10 STARTER MOTOR INSPECTION CARBON BRUSHES When the brushes are worn, the motor will be unable to produce sufficient torque, and the engine will be difficult to turn over. To prevent this, peri- odically, inspect the length of the brushes, replac- ing them when they are too short or chipping.
  • Page 106 5-11 ELECTRICAL SYSTEM STATER MOTOR REASSEMBLY BRUSH HOLDER AND HOUSING END When fixing brush holder to starter motor case, align the protrusion ① of the starter motor case ① ② with the notch ② of the brush holder. SECURING SCREWS Apply thread lock “1324”to starter motor securing screws.

  • Page 107: Lamp

    ELECTRICAL SYSTEM 5-12 LAMP Lamp switch low beam High beam Tail lamp Head lamp Battery Head lamp : 12V 35/35W Tail lamp : 12V 21/5W LAMP BULB REPLACEMENT AND INSPECTION ● After installing a new bulb, check for continuity. If the bulb does not light, inspect the wiring for open or short circuit.

  • Page 108: Switches

    5-13 ELECTRICAL SYSTEM SWITCHES Inspect each switch for continuity with the pocket tester referring to the chart. Pocket tester : 09900-25002 ENGINE KILL SWITCH COLOR Frame Earth POSITION LAMP SWITCH COLOR POSITION WIRE COLOR Gray B / Y Black with yellow tracer Orange.

  • Page 109: Battery

    ELECTRICAL SYSTEM 5-14 BATTERY CAUTION OF BATTERY TREATMENT The battery is needed attention generally as occur flammability gas. If does not, it should be explosion and severe accident. Pay attention to the following points. ∙ Prohibit positively that come in contact with short, spark or firearms. ∙...
  • Page 110 5-15 ELECTRICAL SYSTEM Seal ③ Pouring in battery electrolyte When insert the nozzles of the electrolyte container into the battery’ s electrolyte filler holes, holding the container firmly so that it cloes not fall. Take precaution not to allow any of the fluid to spill. CAUTION In no case pouring into if put in slopely the electrolyte container.
  • Page 111 ELECTRICAL SYSTEM 5-16 ⑤ Separation of electrolyte container. After confirming that the electrolyte has entered the battery completely, remove the electrolyte contain- ers from the battery. CAUTION Draw out slowly otherwise in case of remain electrolyte vaporize. ⑥ Insert of the caps Insert the cap into the filler holes, pressing in firmly so that the top of the caps do not protrude above the upper surface of the battery’...

  • Page 112: Chassis

    CHASSIS CONTENTS FRONT WHEEL 6- 1 FRONT BRAKE 6- 6 FRONT FORK 6-14 STEERING STEM 6-20 REAR WHEEL AND REAR BRAKE 6-25 SUSPENSION 6-31 REAR SWING ARM 6-36...

  • Page 113: Front Wheel

    6-1 CHASSIS FRONT WHEEL REMOVAL ● Support the machine by jack, block or service stand. Service stand : 99000-99094...
  • Page 114 CHASSIS 6-2 ● Disconnect the speedo meter cable. ● Disconnect the left side of the protector. ● Disconnect the clamp. ● Remove the brake hose. ● Pull out the fixing bolt ① and remove the axle ②. ② ① ● Draw out the front axle and take off the front wheel.
  • Page 115 6-3 CHASSIS DISASSEMBLY FRONT WHEEL ● Remove the front brake disk. ● Using the special tool, drive out the wheel bear- ings. Wheel bearing remover : 09941-50110 INSPECTION Play WHEEL BEARING ● Inspect the play of the wheel bearings inner race by hand while fixing it in the wheel hub.
  • Page 116 CHASSIS 6-4 AXLE SHAFT Using the special tools, check the axle shaft for runout and replace it if the runout exceeds the limit. Dial gauge : 09900-20606 Runout of axle shaft Service limit 0.25 mm WHEEL RIM Make sure that the wheel rim runout does not exceed the service limit when checked as shown.
  • Page 117 6-5 CHASSIS ● Install the disk with four bolts as shown in photo. Disk bolt : 18~28 N∙m (1.8~2.8 kg∙m)

  • Page 118: Front Brake

    CHASSIS 6-6 FRONT BRAKE...

  • Page 119: Brake Pad Replacement

    6-7 CHASSIS BRAKE PAD REPLACEMENT ● Remove the caliper mounting bolts and take off the caliper. CAUTION Do not operate the brake lever while dismount- ing the caliper. ● Push the piston and caliper holder all the way to the caliper when removing the pad. ●...
  • Page 120 CHASSIS 6-8 CALIPER REMOVAL AND DISASSEMBLY ● Disconnect the brake hose from the caliper and catch the brake fluid in a suitable receptacle. CAUTION Never re-use the brake fluid left over from the last ser- vicing and stored for long periods. ●...
  • Page 121 6-9 CHASSIS ● Place a rag over piston to prevent popping up. Force out the piston by using air gun. CAUTION Do not use high pressure air to prevent piston damage. ● Remove the piston, piston boot and piston seal. INSPECTION CALIPER CYLINDER Inspect the cylinder bore wall for nick, scratches or...
  • Page 122 CHASSIS 6-10 RUBBER PARTS Inspect the each rubber part for damage and wear. DISC ● M e a s u r e t h e d i s c t h i c k n e s s b y u s i n g t h e micrometer.
  • Page 123 6-11 CHASSIS CALIPER REASSEMBLY Reassemble and remount the caliper in the reverse orders of disassembly and removal, and also carry out the following steps. CAUTION Wash the caliper components with fresh brake fluid before reassembly. Never use cleaning sol- vent or gasoline to wash them. Apply brake fluid to the caliper bore and all internal parts before inserting into the bore.
  • Page 124 CHASSIS 6-12 ● Remove the two clamp bolts and take off the master cylinder. ● Remove the two fitting screws and separate the cap and diaphragm. ● Drain brake fluid. ● Remove the dust seal boot. ● Remove the circlip by using the special tool. Snap ring pliers : 09900-06108 ●...
  • Page 125 6-13 CHASSIS ● Inspect the piston and cup surface for any scratches or other damage. ● Inspect the dust seal boot for wear for damage. REASSEMBLY Reassemble and remount the master cylinder in the reverse orders of disassembly and removal, and also carry out the following steps : CAUTION Wash the master cylinder components with fresh...

  • Page 126: Front Fork

    CHASSIS 6-14 FRONT FORK...
  • Page 127 6-15 CHASSIS REMOVAL AND DISASSEMBLY ● Take off the front wheel. (See page 6-1) ● Loosen the front fork upper and lower clamp bolts. ● Remove the front brake hose clamp. ● Pull down right and left front forks. ● Remove the front fork cap, O-ring ①, and seat lever.
  • Page 128 CHASSIS 6-16 ● Straighten the fork and stroke it several times to remove the oil. ● Hold the fork inverted for a few minutes. ● Remove the damper rod bolt by using the 19 mm socket. ● Separate the inner tube from outer tube. ●...
  • Page 129 6-17 CHASSIS INSPECTION DAMPER ROD RING Inspect the damper rod ring for wear and damage. INNER TUBE AND OUTER TUBE Inspect the inner tube and outer tube sliding sur- faces for any scuffing or flaws. FORK SPRING Measure the fork spring free length. If it is shorter than the service limit, replace it.
  • Page 130 CHASSIS 6-18 OIL SEAL Install the oil seal to the outer tube by using the special tool as shown. Fork oil seal installer : 09940-50112 FORK OIL ● For the fork oil, be sure to use a front fork oil whose viscosity rating meets specifications below.
  • Page 131 6-19 CHASSIS REMOUNTING ● Maintain equally right and level height. (Standard for upside surface of the upper bracket : 7 mm±1 mm) ● Tighten the upper and lower clamp bolts. Upper clamp bolts : 22~35 N∙m (2.2~3.5 kg∙m) Lower clamp bolts : 20~30 N∙m (2.0~3.0 kg∙m)

  • Page 132: Steering Stem

    CHASSIS 6-20 STEERING STEM...
  • Page 133 6-21 CHASSIS REMOVAL AND DISASSEMBLY ● Take off the front wheel. (See page 6-1) ● Take off the front fork. (See page 6-15) ● Remove the screws ② and the two headlight housing rubber packing ①. ① ① ② ● Disconnect the lead wires. ●...
  • Page 134 CHASSIS 6-22 ● Remove the handlebars clamp bolts. ● Remove the steering stem head bolt and take off the steering stem upper nut. ● Remove the steering stem nut and draw out the steering stem. CAUTION Hold the steering stem lower bracket by hand to prevent from falling.
  • Page 135 6-23 CHASSIS ● Remove the outer race fitted on the steering stem. This can be done with a chisel. ● Draw out the two inner races fitted to the top and bottem ends of the head pipe. INSPECTION Inspect and check the removed parts for the fol- lowing abnormalities.
  • Page 136 CHASSIS 6-24 BEARING ● When press the bearing, use the special tool. STEERING STEM NUT ● Tighten the steering stem nut with the special tool. Clamp wrench : 09940-10122 steering stem nut : 40~50 N∙m (4.0~5.0kg∙m) ● Turn the steering stem right and left, lock-to- lock, five or six times.

  • Page 137: Rear Wheel And Rear Brake

    6-25 CHASSIS REAR WHEEL AND REAR BRAKE REMOVAL ● Support the machine by jack or block or service stand. Service stand : 99000-99094...
  • Page 138 CHASSIS 6-26 ● Pull out the cotter pin and remove the torque link nut and bolt. ● Remove the rear brake adjuster nut. ● Remove the rear axle nut. ● Draw out the axle shaft and take off the rear wheel.
  • Page 139 6-27 CHASSIS ● Remove the right and left side wheel bearings. CAUTION Removing the left side bearing first makes the job easier. REAR BRAKE ● Take off the brake shoes. ● Loosen the cam lever nut. ● Pull off the brake cam, washer, O-ring and cam lever.
  • Page 140 CHASSIS 6-28 AXLE SHAFT Using a dial gauge, check the axle shaft for runout and replace it if the runout exceeds the limit. Dial gauge(1/100) : 09900-26006 Magnetic stand : 09900-20701 “V”Block : 09900-21304 Axle shaft runout Service limit 0.25 mm WHEEL RIM Make sure that the wheel rim runout does not exceed the service limit when checked as shown.
  • Page 141 6-29 CHASSIS REAR BRAKE DRUM Measure the brake drum I. D. to determine the extent of wear and, if the limit is exceeded by the wear noted, replace the drum. The value of this limit is indicated inside the drum. Rear brake drum I.
  • Page 142 CHASSIS 6-30 BRAKE CAM Apply grease to the brake cam. Super grease “A” CAUTION Be careful not to apply too much grease to the brake cam shaft. If grease gets on the lining, brake slippage will result. BRAKE CAM LEVER Tighten the cam lever bolt with specified torque.

  • Page 143: Suspension

    6-31 CHASSIS SUSPENSION � (Service limit 10.20 mm) � (Service limit 10.20 mm) � (Service limit 14.20 mm)
  • Page 144 CHASSIS 6-32 REMOVAL AND DISASSEMBLY ● Remove the seat and frame covers. ● Remove the rear wheel. (See page 6-26) ● Loosen the four screws and remove the mud flap. ● Remove the rear cushion rod fitting nuts and bolts. ●...
  • Page 145 6-33 CHASSIS ● Remove the rear cushion rod nut and bolt. ● Remove the spacers from the rear cushion rod. ● After drawing out the spacer, remove the two bearings from the rear cushion lever by using the special tools. Bearing remover (17 mm) : 09923-73210 Rotor remover sliding shaft : 09930-30102 INSPECTION...
  • Page 146 CHASSIS 6-34 SPACER Measure the inside diameter of the spacer with dial calipers. � Service limit 14.20 mm Spacer � Service limit 10.20 mm (�, �：See page 6-31, 6-36) If the inside diameter of the spacer exceeds the service limit or flaws are discovered, replace the spacer and O-rings.
  • Page 147 6-35 CHASSIS � � � Rear shock absorber nut(Upper) : 40~60 N∙m (4.0~6.0 kg∙m) � Rear cushion lever center nut : 70~100 N∙m (7.0~10.0 kg∙m) � Rear cushion rod nut and bolt(Lower) : 84~120 N∙m (8.4~12.0 kg∙m) � Rear cushion rod nut and bolt(Upper) : 84~120 N∙m (8.4~12.0 kg∙m) �...

  • Page 148: Rear Swing Arm

    CHASSIS 6-36 REAR SWING ARM � (Service limit 14.20 mm) � (Service limit 14.20 mm) REMOVAL AND DISASSEMBLY ● Remove the rear wheel. (See page 6-26) ● Loosen the four screws and remove the mud flap. (See page 6-32) ● Remove the rear cushion rod fitting nuts and bolts. (See page 6-32) ●...
  • Page 149 6-37 CHASSIS ● Remove the swing arm pivot nut. ● Draw out the pivot shaft and take off the swing arm. ● Remove the chain case. ● Remove the two spacers. ● Remove the spacer by using the special tools. Bearing remover (17 mm) : 09923-73210 Rotor remover sliding shaft : 09930-30102 INSPECTION...
  • Page 150 CHASSIS 6-38 SPACER Apply grease to the spacer when installing. Super grease “A”...

  • Page 151: Servicing Information

    SERVICING INFORMATION CONTENTS TROUBLESHOOTING 7- 1 SPECIAL TOOLS 7- 8 TIGHTENING TORQUE 7-12 SERVICE DATA 7-14 WIRE AND CABLE ROUTING 7-21 WIRING DIAGRAM 7-23...

  • Page 152: Troubleshooting

    7-1 SERVICING INFORMATION TROUBLESHOOTING ENGINE Complaint Symptom and possible causes Remedy Engine will not Compression too low start, or is hard 1. Valve clearance out of adjustment. Adjust. to start. 2. Worn valve guides or poor seating of valves. Repair or replace. 3.
  • Page 153 SERVICING INFORMATION 7-2 Complaint Symptom and possible causes Remedy Noisy engine. Noise seems to come from transmission 1. Gears worn or rubbing. Replace. 2. Badly worn splines. Replace. 3. Primary gears worn or rubbing. Replace. 3. Badly worn bearings. Replace. Slipping clutch.
  • Page 154 7-3 SERVICING INFORMATION Complaint Symptom and possible causes Remedy Engine lacks power. 1. Loosen of valve clearance. Adjust. 2. Weakened valve springs. Replace. 3. Valve timing out of adjustment. Adjust. 4. Worn piston ring or cylinder. Replace. 5. Poor seating of valves. Repair or replace.
  • Page 155 SERVICING INFORMATION 7-4 ELECTRICAL Complaint Symptom and possible causes Remedy No sparking or poor 1. Defective ignition coil. Replace. sparking. 2. Defective spark plug. Replace. 3. Defective CDI unit. Replace. Spark plug soon 1. Mixture too rich. Adjust carburetor. become fouled with 2.
  • Page 156 7-5 SERVICING INFORMATION BATTERY Complaint Symptom and possible causes Remedy “Sulfation”acidic 1. Not enough electrolyte. Add distilled water, if the battery white powdery has not been damaged and substance or spots “sulfation” has not advanced on surfaces of too far, and recharge. cell plates.
  • Page 157 SERVICING INFORMATION 7-6 CHASSIS Complaint Symptom and possible causes Remedy Steering feels too 1. Steering stem nut overtightened. Adjust. heavy or stiff. 2. Worn bearing or race in steering stem. Replace. 3. Distorted steering stem. Replace. 4. Not enough pressure in tires. Adjust.
  • Page 158 7-7 SERVICING INFORMATION BRAKES Complaint Symptom and possible causes Remedy Poor braking 1. Not enough brake fluid in the reservoir. Refill to level mark. (FRONT and REAR) 2. Air trapped in brake fluid circuit. Bleed air out. 3. Pads worn down. Replace.

  • Page 159: Special Tools

    SERVICING INFORMATION 7-8 SPECIAL TOOLS Special tools Part Number∙Part Name∙Description Special tools Part Number∙Part Name∙Description 09900-20205 09900-00401 Micrometer “L”type hexagon wrench set (1/100mm, 0-25mm) Tighten hexagon bolt Measure outside diameter of piston pin 09900-20508 09900-00410 Cylinder gauge set Hexagon wrench set (1/100mm, 40-80mm) Tighten hexagon bolt Measure inside diameter of cylinder...
  • Page 160 7-9 SERVICING INFORMATION Special tools Part Number∙Part Name∙Description Special tools Part Number∙Part Name∙Description 09900-22401 09913-60710 Small bore gauge Bearing remover (10-18mm) Measure inside diameter of conrod small-end Remove bearing with the rotor remove sliding shaft 09900-25002 09913-75520 Pocket tester Bearing installer Measure voltage, electric current, resistance Used to drive bearing in 09900-26006...
  • Page 161 SERVICING INFORMATION 7-10 Special tools Part Number∙Part Name∙Description Special tools Part Number∙Part Name∙Description 09916-14510 09923-74510 Valve spring compressor Bearing remover (20~35mm) Remove and remounting valve stem Remove bearing with the rotor remove sliding shaft 09916-14910 09924-84521 Valve spring compressor attachment Bearing installer Used with valve spring compressor Used to drive small bearing in...
  • Page 162 7-11 SERVICING INFORMATION Special tools Part Number∙Part Name∙Description 09940-34561 Front fork assembling tool attachment “D” Used with T-handle 09940-50113 Front fork oil seal installer Install front fork oil seal 09941-34513 Bearing installer Install steering outer race 09941-50110 Wheel bearing remover Remove wheel bearing 09943-74111 Front fork oil level gauge...

  • Page 163: Tightening Torque

    SERVICING INFORMATION 7-12 TIGHTENING TORQUE ENGINE ITEM N∙m kg∙m Cylinder head cover bolt 12-16 1.2-1.6 Camshaft sprocket bolt 25-30 2.5-3.0 Cylinder head nut 25-29 2.5-2.9 Cylinder base nut 0.6-0.8 Magneto rotor nut 56-60 5.6-6.0 primary drive gear/oil pump drive gear nut 40-60 4.0-6.0 Clutch sleeve hub nut...
  • Page 164 7-13 SERVICING INFORMATION CHASSIS ITEM N∙m kg∙m Front axle bolt 50-80 5.0-8.0 Front axle pinch bolt 15-25 1.5-2.5 Front fork damper rod bolt 30-40 3.0-4.0 Front fork lower clamp bolt 20-30 2.0-3.0 Front fork upper clamp bolt 22-35 2.2-3.5 Steering stem head bolt 80-100 8.0-10.0 Handlebars clamp bolt...

  • Page 165: Service Data

    SERVICING INFORMATION 7-14 TIGHTENING TORQUE CHART For other bolts and nuts who’ s torque is not listed, refer to this chart : Conventional or “4”marked bolt “7”marked bolt Bolt Diameter (mm) kg∙m kg∙m N∙m N∙m 1.0-2.0 0.1-0.2 1.5-3.0 0.15-0.3 2.0-4.0 0.2-0.4 3.0-6.0 0.3-0.6...
  • Page 166 7-15 SERVICING INFORMATION CAMSHAFT + CYLINDER HEAD Unit : mm ITEM STANDARD LIMIT 34.44-34.48 34.18 Cam height 33.81-33.85 33.55 Camshaft runout 0.10 Cam chain 20-pitch length 129.9 Rocker arm I.D. IN. & EX. 12.000-12.018 Rocker arm shaft O.D. IN. & EX. 11.977-11.995 Cylinder head distortion 0.05...
  • Page 167 SERVICING INFORMATION 7-16 CONROD + CRANKSHAFT Unit : mm ITEM STANDARD LIMIT Conrod small end I.D. 15.006-15.014 15.040 Conrod deflection Conrod big end side clearance 0.10-0.45 1.00 Conrod big end width 15.95-16.00 Crank web to wed width 53.0±0.1 Crankshaft runout 0.05 OIL PUMP Unit : mm...
  • Page 168 7-17 SERVICING INFORMATION TRANSMISSION+DRIVE CHAIN Unit : mm except ratio ITEM STANDARD LIMIT Primary reduction ratio 3.500 (70/20) Final reduction ratio 3.357 (47/14) 2.750 (33/12) 1.785 (25/14) Gear ratios 1.368 (26/19) 1.045 (23/22) 0.913 (21/23) 0.50 Shift fork to groove clearance 0.10-0.30 No.
  • Page 169 SERVICING INFORMATION 7-18 CARBURETOR ITEM SPECIFICATION Carburetor type PD 18F Bore size ф 24 I.D. No. HG 58 Idle rpm 1,450±100 rpm Float height 12.5 (M.J.) # 98 Main jet Main air jet (M.A.J.) # 90 Jet needle (J.N.) J 29 B Needle jet (N.J.) AIFC-2nd...

  • Page 170: Tire Pressure

    7-19 SERVICING INFORMATION BRAKE+WHEEL Unit : mm ITEM STANDARD LIMIT 20-30 Front brake lever distance Rear brake pedal free travel 10-20 Rear brake pedal height Front wheel Brake disc thickness Front wheel 0.30 Brake disc runout Master cylinder bore Front wheel 12.700-12.743 Front wheel 12.657-12.684...
  • Page 171 SERVICING INFORMATION 7-20 SUSPENSION Unit: mm ITEM STANDARD LIMIT Front fork stroke Front fork spring free length Front fork oil level Rear wheel travel Swing arm pivot shaft runout ELECTRICAL Unit : mm ITEM SPECIFICATION 15� /2,250 and 35� /4,000 Ignition timing (BTDC/rpm) Type C8EH-9...

  • Page 172: Wire And Cable Routing

    7-21 SERVICING INFORMATION WIRE AND CABLE ROUTING WIRING HARNESS Clutch cable Tail stop lamp 09407-254A1 Air vent hose License plate C.D.I Unit lamp 09404-06401 Starter cable Magneto Neutral switch Breather hose Handle switch R/H Front brake hose Neutral switch 09407-14403 Magneto Starter relay 09407-14403...
  • Page 173 SERVICING INFORMATION 7-22 CABLE Front brake hose Handle switch L/H Handle switch R/H 09407-14403 09407-14403 Clutch cable Throttle cable Starter cable 09407-14403 View P Throttle cable Speedometer cable 09407-254A1 Oil cooler Oil cooler 09407-14401 Clutch cable 09403H9304 Rear brake switch Fuse assembly Clamp Battery �...

  • Page 174: Wiring Diagram

    7-23 SERVICING INFORMATION WIRING DIAGRAM...
  • Page 175 Prepared by HYOSUNG MOTORS & MACHINERY INC. Overseas Technical Department 1st Ed. Feb. 1999 Manual No. 99000-97100 Printed in Korea...

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