Honda MBX50 Workshop Manual
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Honda MBX50 Workshop Manual

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�HONDA
� MBX50· MBX80

WORKSHOP MANUAL

HOW TO USE THIS MANUAL
This shop manual describes the service procedures
for the HONDA MBX50 and MBXBO based on
the M BX50 Standard model.
Section 1 throughs 3 apply to the whole motor­
cycle, while section 4 through 17 describe parts
of the motorcycle, grouped according to loca­
tion.
Find the section you want on this page, then
turn to the table of contents on page 1 of that
section.
Most sections start with an assembly or system
illustration, service information and trouble­
shooting for the section. The subsequent pages
give detailed procedures.
If you don't know the source of the trouble, go
to section, 18, TROUBLESHOOTING.
ALL INFORMATION, ILLUSTRATIONS, DIREC­
TIONS AND SPECIFICATIONS INCLUDED IN
THIS PUBLICATION ARE BASED ON THE LATEST
PRODUCT INFORMATION AVAILABLE AT THE
TIME OF APPROVAL FOR PRINTING HONDA
MOTOR CO., LTD. RESERVES THE RIGHT TO
MAKE CHANGES AT ANY TIME WITHOUT
NOTICE AND WITHOUT INCURRING ANY
OBLIGATION WHATEVER.
NO PART OF THIS PUBLICATION MAY
BE REPRODUCED WITHOUT WRITTEN
PERMISSION.
HONDA MOTOR CO., LTD.
SERVICE PUBLICATIONS OFFICE
MB
BO
B
INSPECTION AND AJUSTMENT
ENGINE REMOVAL/INSTALLATION
LU
z
Clutch/KICKSTARTER/
i============================-�
(!)
z
LU
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Cf)
Cf)
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Summary of Contents for Honda MBX50

  • Page 1: Workshop Manual

    WORKSHOP MANUAL HOW TO USE THIS MANUAL This shop manual describes the service procedures GENERAL INFORMATION for the HONDA MBX50 and MBXBO based on the M BX50 Standard model. LUBRICATION Section 1 throughs 3 apply to the whole motor­ INSPECTION AND AJUSTMENT cycle, while section 4 through 17 describe parts of the motorcycle, grouped according to loca­...
  • Page 2 �HONDA � MBX50·MBX80 MODEL IDENTIFICATION (1) BEGINNING WITH F No. AC03-5000001. (3) The engine serial number is stamped on the (2) The frame serial number is stamped on the left crankcase. steering head right side. (4) The carburetor identification number is on...
  • Page 4 HONDA � MBX50·MBX80 GENERAL INFORMATION · S PECIFICATIONS AREA MSX80 ITEM MBX50 (Type) DIMENSIONS Overall length 1,970 mm (77.5 in) Overall width 675 mm (26.6 in) Overali height Standard 1,005 mm (39.6 in) Deluxe 1,110 mm (43.7 in) 1,250 mm (49.2 in)
  • Page 5 �HONDA � MBXSO, MBX80 GENERAL INFORMATION AREA MBXSO ITEM MBX50 (Type) ENGINE 5.8 kw/7,000 min- 1 7.0 kw/5,750 min- 1 Maximum horsepower (7.9 ps/7,000 rpm) (9.6 ps/5,750 rpm) ·8".3 N.m (0.85 kg-m , 6.1 ft-lb )/ 11.7 N.m (1.2 kg-m, 8.7 ft-lb)
  • Page 6 HONDA � MBXSO· MBX80 GENERAL INFORMATION TORQUE VALUES e ENGINE Torque Remarks O'ty Thread Dia (mm) Item N.m (kg-m, ft-lb) 18-22 (1.8-2.2, 13-16) Cylinder head 50-60 (5.0-6.0, 36-43) Alternator rotor 45-55 (4.5-5.5, 33-40) Primary drive gear 20-25 (2.0-2.5, 14-18)
  • Page 7 �HONDA � MBX50· MBXIO GENERAL INFORMATION TOOLS SPECIAL Tool Name Tool No. O'ty Remarks Crankshaft assembly tool 07965-1660100 Crankshaft installation Balancer weight driver 07945-1660000 Balancer installation Bearing remover set 12mm 07936-1660000 Removal of small balancer bearing, water pump bearing and mainshaft bearing...
  • Page 8 �HONDA � MIX50· MBXIO MEMO...
  • Page 9 HONDA MBX50·MBX80 GENERAL INFORMATION CABLE & HARNESS ROUTING (1) RADIATOR OVERFLOW TUBE (2) HIGH TENSION CORD (4) TACHOMETER CABLE (3) CLUTCH CABLE (' · / ( f ! J. I (6) WIRE HARNESS ' ; . · · . �/ ;.
  • Page 10 �HONDA � MBX50· MBX80 GENERAL INFORMATION (5) Al TERNATOR/NEUTRAL SWITCH WIRES (4) WIRE HARNESS...
  • Page 11 �HONDA � MBX5. 0 ·MBX80 GENERAL INFORMATION (1) CLUTCH CABLE (2) TURN SIGNAL SWITCH COUPLER (3) THROTTLE CABLE (5) BRAKE HOSE (8) IGNITION COIL ( 6) OIL LEV EL ( 7 ) ( 9) CDI UNIT SENSOR (10) HIGH TENSION CORD...
  • Page 12 MUFFLER DECARBONIZATION Page 3- 1 3 * SHOULD BE SERVICED BY AN AUTHORIZED HONDA DEALER' UNLESS THE OWNER HAS THE PROPER TOOI-S AND SERVICE DATA AND IS MECHANICALLY QUALIFIED. REFER TO THE OFF I CAL HONDA SHOP MANUAL. *ii IN THE INTEREST OF SA!=ETY, WE RECOMMEND THESE ITEMS BE SERVICED ONLY BY AN AUTHORIZED HONDA DEALER.

  • Page 13: Oil Flow

    LUBRICATIO �HONDA � MBX50· MBXSO (1) ENGINE OIL FLOW (4) OIL PUMP OIL TANK CAPACITY: 1.2 lit. (1.3 US qt, 1.1 Imp qt) (7) OIL PUMP Do not attempt to disassemble the oil pump. (8) OIL PUMP BLEEDER BOLT -- - ----- - - r-...
  • Page 14 �HONDA � MBXSO· MBXSO LUBRICATION OIL FLOW SERVICE INFORMATION TROUBLESHOOTING TRANSMISSION 01 L 01 L STRAINER CLEANING 2- 5 OIL PUMP REMOVAL OIL PUMP INSPECTION OIL PUMP INSTALLATION 2 -7 01 L PUMP BLEEDING OIL TANK CHASSIS LUBRICATION POINTS...

  • Page 15: Service Information

    INJECTOR OIL Oil capacity 1.2 lit. (1.3 US qt, 1.1 Imp qt) Oil recommendation Honda 2 Stroke Injector Oil or its equivalent TRANSMISSION OIL 0.9 lit. (1.0 US qt, 0.8 Imp qt) at disassembly Oil capacity 0.8 lit. (0.8 US qt, 0.7 Imp qt) at change...

  • Page 16: Transmission Oil

    �HONDA � MBX50· MBX.80 LUBRICATION TRANSMISSION Oil OIL LEVEL CHECK Before checking the oil level run the engine and ·allow to idle for a few minutes. Support the motorcylce upright on level ground. Stop the engine and remove the oil level check bolt from the right crankcase cover.

  • Page 17: Oil Tank

    HONDA � MBX50· MBXSO LUBRICATION Oil STRAINER CLEANING (1) OIL PUMP Disconnect the oil tube at the oil pump and allow the oil to drain into a clean container. (2) OIL TUBE Remove the right side cover. Loosen the tube clip and disconnect the oil tube (1) OIL STRAINER-ml joint under the oil tank.
  • Page 18 LUBRICATION {1) OIL PUMP MOUNTING BOLT {2) SCREW NOTE Before removing the oil pump, clean the oil pump and crankcase. Remove the carburetor (Page 4-3). Disconnect the oil pump control cable. Remove the left crankcase cover. (Page 8-3). Remove the bolt and screw attaching the oil pump. (3) OIL PASS TUBE (4) OIL TUBE Disconnect the oil tube from the oil pump, and...
  • Page 19 �HONDA � MBX50· MBXSO LUBRICATION (2) CONTROL LEVER (1) MAT ING FACE Remove the oil pump and inspect the following items: Damaded or weakened 0-rings. Damage to crankcase mating face. Damage to pump body. Improper oil control lever. CAUTION Do not disassemble the oil pump.
  • Page 21 HONDA MBX50°MBXSO LUBRICATION OIL TANK (1) OIL TANK MOUNTING BOLT REMOVAL/INSTALLATION Remove the seat, right and left side covers. Remove the fuel tank and air cleaner case (Page 4-10). Remove the rear suspension linkage mudguard (Page 13-13). Disconnecto the oil tube at the oil pump and drain the oil.
  • Page 22 �HONDA � MBX50· MBX80 LUBRICATION (5) FRON T FORK (4) CLUT C H AND BRA KE (A.T. LEVER PIVOTS � / / (6) or CABLE LUBRICANT (1) WHEEL BEARINGS (3) THROTTLE SPEEDOMETER AND GRIP TACHOMETER CABLES � STEER I NG HEAD BEARINGS I�...
  • Page 23 @ · See page 2-4. m Oil pump See page 6-4. a Cylinder head and piston decarbonizing See page 6-6. e Cylinder exhaust port decarbonizing MBX50 MBX80 SPECIFICARIONS <Engine> +-­ NGI< BR9ES, ND W2J.ESR-U Spark plug: Standard NGI< BR8ES, ND W24ESR-U +-­...
  • Page 24 HONDA MBX50·MBX80 INSPECTION AND ADJUSTMENT FUEL UNE AND FUEL STRAINER (1) FUEL VALVE (2) FUEL LINE Turn the fuel valve OFF and remove the strainer cup, 0-ring and filter screen from the fuel valve body. (3) FUEL STRIANER CUP Wash the strainer cup and filter screen in high flash point solvent.
  • Page 26 HONDA MBX50,MBX80 INSPECTION AND ADJUSTMENT Wash the element in non-flammable or high flash point solvent and allow to dry. NOTE D o not wash the element in gasoline or vege­ table oil. Soak the element in clean engine oil or gear oil (SAE 80-90) and squeeze out any excess.
  • Page 27 (1) THROTTLE SOP SCREW Screw in the air screw until it lightly seats, then turn it out specified turns. MBX50: 1% turns (E type: 1% turns) MBX80: 1 turn Reset idle speed with the throttle stop screw. Turn the air screw to find the highest idle speed.
  • Page 30 �HONDA � MBX50· MBXSO INSPECTION AND ADJUSTMENT RADIATOR COOLANT (1) RESERVE TANK Check the coolant level of the reserve tank with the engine running at normal operating tempera­ ture. The level should be between the "F" (FULL) and "L" ( LOW) level lines.
  • Page 32 �HONDA � MBXSO· MBX80 INSPECTION AND ADJUSTMENT REAR BRAKE (1) ADJUSTING NUT REAR BRAKE PEDAL PLAY Measure the brake pedal free play. FREE PLAY: 20-30 mm (3/4-1-1/4 in) If adjustment is necessary, turn the rear brake adjusting nut. (1) ARROW MARK...
  • Page 33 �HONDA � MBX50· MBXSO INSPECTION AND ADJUSTMENT DRIVE CHAIN INSPECTION Shift the transmission into neutral. Measure the drive chain slack between the sprock­ ets. CHAIN SLACK: 10-20 mm (3/8-3/4 in) (1 )ADJUSTING NUT (2) GRADUATED SCALE (3 ) INDEX MARK...

  • Page 35: Inspection And Adjustment

    RECOMMENDED TIRE PRESSURE AND TIRE SIZE: Cold tire pressure kPa(kg/cm ,psi) Up to 90kg Up to capacity Tire size ( 1981b) load MBX50 Front 2.50-18-4PR 175(1.75,25) 175(1.75,25) Rear 2.75-18-6PR 175( 1.75,25) 280( 2.8,40) MBXBO Front 2. 75-18-4PR 200(2.0,28) 200(2.0,28)
  • Page 36 �HONDA � MBXSO, MBXSO ( 1) Align with frame pipe. 4 -0...
  • Page 37 �HONDA �. M BX50, MBXSO FUEL SYSTEM 4 -7 SERVICE INFORMATION FLOAT LEVEL ADJUSTMENT TROUBLESHOOTING THROTTLE VALVE/CABLE INSTALLATION CARBURETOR REMOVAL 4 - 9 CARBURETOR INSTALLATION THROTTLE VALVE DISASSEMBLY 4 - 9 FUEL TANK 4 -5 FLOAT/FLOAT VALVE/JET 4 -1 0...
  • Page 39 HONDA MBX50 Ml!UU&O ° FUEL SYSTEM (1) FUEL VALVE Clean the carburetor and its surrounding area thoroughly. Turn the fuel valve to OFF and drain fuel from the tank through the drain tube. Disconnect the fuel line. Disconnect the drain tube.
  • Page 40 HONDA MBX50,MBX80 FUEL SYSTEM THROTTLE VALVE DISASSEMBLY (1) CARBURETOR TOP Remove the carburetor top and pull out the throttle valve. (1) THROTTLE VALVE Disconnect the throttle cable from the throttle valve. (1) SEALING CAP Remove the return spring, carburetor top and sealing cap.
  • Page 41 �HONDA � MBXSO· MBX80 FUEL SYSTEM Pry off the cable clip and remove the jet needle. Check the jet needle and throttle valve for wear to damage. �(1) C ABLECLIP NEEDLE CLIP Standard position: 2nd groove (3) JET NEEDLE (4) , THROTTLE...
  • Page 42 �HONDA � MBXSO· M!SX80 FUEL SYSTEM Remove the main jet, needle jet holder and needle � (2) MAIN JET (1) STOP SCREW jet. r��4frr.. Remove the stop screw and air screw. l- ( 3) NEEDLE JET HOLDER NOTE '� ��...
  • Page 43 �HONDA � MBX50· MBX80 FUEL SYSTEM JETS/FLOAT VAlV[/flOAT ASSEMBLY (2) MAIN JET (1) SLOW JET Install the needle jet, needle jet holder and main jet. Install the air and stop screws by turning them into their original positions. (3) STOP SCREW...
  • Page 44 �HONDA � MBXSO· MBXSO FUEL SYSTEM THROTTLE VALVE/CABLE (5) SEALING CAP INSTALLATION (1) CABLE Install the jet needle on the throttle valve and secure CLIP with the cable clip. Install the sealing cap, carburetor top and return (4) NEEDL ( 2) JET spring.
  • Page 46 �HONDA � MBX50·MBXS0 FUEL SYSTEM AIR CLEANER AIR CLEANER CASE REMOVAL Remove the seat and fuel tank. Loosen the air cleaner tube band. Remove the bolts tightening the battery holder and radiator reserve tank. (1) BOLTS (1) BOLTS Remove the bolts attaching the air cleaner case and case.
  • Page 47 :g:�t:o ENGINE REMOVAL/INSTALLATION (1) DRIVE CHAIN MASTER LINI< (2) RETAII\IING CLIP Note the installation...
  • Page 49 , Kickstarter • Coo}ing system SPECIFICATIONS Engine dry weight MBX50: Approximately 17.5 kg (38.6 lb) MBX80: Approximately 18.9 kg (41.7 lb) Transmission oil capacity 0.9 lit. (1.0 US qt, 0.8 Imp qt) at engine assembly 0.8 lit. (0.8 US qt, 0.7 Imp qt) at change...
  • Page 50 �HONDA � MBXSO, MBXSO ENGINE REMOVAL/INSTALLATION ENGINE REMOVAL (1) EXHAUST PIPE FLANGE NUTS On the Deluxe model, remove the under cowl (Page 14 -3 ) Drain the transmission oil (Page 2-3). Remove the two exhaus� pipe flange nuts. (1) MUFFLER Remove the muffler mounting nut and remove the muffler.
  • Page 51 �HONDA � MBX50· MBX80 ENGINE REMOVAL/INSTALLATION Remove the radiator cap. it21i/&i;i;j�ji(fij�������� � � � -----, Engine must be cool before removing the radiator cap, or severe scalding may result. Remove the drain bolt and drain the coolant. (2) DRAIN BOLT...
  • Page 52 �HONDA � MBXSO, MBX80 ENGINE REMOVAL/INSTALLATION (1) ALTERNATOR/NEUTRAL SWITCH WI RE CONNECTORS Disconnect the alternator and neutral switch wire connectors. (1) AIR CLEANER TUBE BAND Loosen the air" cleaner tube band. Remove the two carburetor mounting nuts, carbure­ tor and insulator.
  • Page 55 CYLINDER HEAD/CYLINDER/ HONDA PISTON MBX50·MBX80 8-12 N.m (0.8-1.2 kg-m, 6-9 ft-lb)
  • Page 56 �HONDA � MBX50· MBXSO CYLINDER HEAD/CYLINDER/PISTON SERVICE INFORMATION TROUBLESHOOTING 6- 3 CYLINDER HEAD 6- 5 CYLI N DE A/PISTON 6-10 REED VALVE...
  • Page 57 8-12 N.m (0.8-1.2 kg-m, 6-9 ft-lb) SPECIFICATIONS ITEM STANDARD mm (in) SERVICE LIMIT mm (in) Cylinder head warpage 0.10 (0.004) Cylinder bore MBX50 38.998-39.013 mm (1.5354-1.5359 in) 39.062 mm ( 1.5379 in) MBX80 49.407-49.523 mm (1.9452-1.9497 in) 49.572 mm (1.9516 in) Piston 0.0.
  • Page 58 �HONDA � Ml!lXSO, MBXSO CYLINDER HEAD/CYLINDER/PISTON (1) RADIATOR CAP REMOVAL On the Deluxe model, remove the under cowl (Page 5-3). Remove the seat, both side covers and fuef. tank. Remove the radiator cap. Engine must be cool before removing the radiator cap, or severe scalding may result.
  • Page 60 �HONDA � MBXSO· MBXSO CYLINDER HEAD/CYLINDER/PISTON CYLINDER/PISTON CYLINDER REMOVAL Remove the exhaust pipe (Page 5 - 3 ) . Remove the cylinder head (Page 6-3). MUFFLER (1) INTAl<E PIPE (2) OIL PUMP Remove the carburetor (Page 4-3). Remove the four flange bolts attaching the intake pipe to the cylinder and remove the intake pipe.
  • Page 62 {:;;ijj\ HONDA � MBX50· MBXSO CYLINDER HEAD/CYLINDER/PISTON Inspect the cylinder bores for wear at three levels in X and Y directions. Take the minimum figure measured to determine the cylinder wear. Avoid the port area. SERVICE LIMIT: MBX50 39.062 mm (1.5379 in) MBX80 49.572 mm (1.9516 in)
  • Page 64 �HONDA � MBX50· MBX80 CYLINDER HEAD/CYLINDER/PISTON PISTON/CYLINDER INSTALLATION Install the expander and piston rings. NOTE Install the rings with the marking facing "' The top and second rings are interchange­ able with each other. • Do not mix different brands of rings in an engine.
  • Page 66 �HONDA � MBX50· MBX80 . CYLINDER HEAD/CYLINDER/PISTON (1) REED VALVE Remove the reed valve. (1) REED STOPPERS (2) REEDS INSPECTION Check the reeds for damage of fatigue and replace if necessary. Replace the valve with a new one if the seat rubber is cracked or damaged, or if there is clearance between the reed and seat.

  • Page 67: Gearshift Linkage

    CLUTCH/KICKSTARTER/ �HONDA GEARSHIFT LINKAGE � MBX50· MBX80 (3) Align the balancer timing when installing the clutch outer. (2) Thickness.: 0.5 mm) (0.02 in) ( 1) Thickness: 1.0 mm (0.04 in) Three p lates and four discs (4) WATER PUMP SHAFT...
  • Page 68 �HONDA � MBX50, MBX80 CLUTCH/KICKSTARTER/GEARSHI FT LINKAGE 7- 2 S ERVICE INFORMATION CLUTCH INSTALLATION/ 7-10 BALANCER TIMING TROUBLJ;SHOOTING KICKSTARTER 7-11 RIGHT CRANKCASE COVER SHIFT LINKAGE 7-14 CLUTCH/IDLER GEAR...

  • Page 69: Specifications

    HONDA MBX50·MBX80 CLUTCH/KICKSTARTER/GEARSHIFT LINKAGE SERVICE INFORMATION GENERAL INSTRUCTIONS a All clutch and kickstarter maintenance and inspections can be accomplished with the engine installed. e Make balancer timing adjustment when the clutch outer and primary drive gear are removed. e Use the UNIVERSAL HOLDER to remove and install the primary drive gear.
  • Page 70 �HONDA � MBX50·MBX80 CLUTCH/KICKSTARTER/GEARSHIFT LINKAGE RIGHT CRANKCASE COVER (1) CLUTCH CABLE (2) TACHOMETER CABLE REMOVAL On the Deluxe model, remove the under cowl (Page 14-3). Drain the coolant (Page 10-3). Drain oil from the transmission. Remove the kickstarter pedal. Disconnect the clutch cable from the clutch arm.
  • Page 71 �HONDA. � MBXSO· MBXSO CLUTCH/KICKSTARTER/Gl;8RSHI FT LINKAGE Remove the tachometer gear. � ( 1) OIL SEA L NOTE j Do not forget to install the washer. (2) WASHERS ( 3 ) TACHOMETER GEAR INSTALLATION (1) CLUTCH ARM Install the clutch arm and clutch lifter rod.
  • Page 72 �HONDA � MBX50· MBXSO CLUTCH/KICKSTARTER/GEARSHIFT LINKA GE Install the right crankcase cover on the crankcase. Install the clutch cable bracket and tighten with the flange bolt. NOTE Tighten the bolts in a crisscross pattern and in two or three steps.
  • Page 73 �HONDA � MBX50· MBX80 CLUTCH/KICKSTARTER/GEARSHI FT LINKAGE Remove the circlip. (1) CLUTCH DISCS (2 ) PRESSURE (3) CLUTCH Remove the clutch center, clutch discs, clutch (MBX80: 4 discs) PLATE OUTER plates, and clutch pressure plate. Remove the spline washer and remove the clutch outer.
  • Page 74 �HONDA � MBXSO· MBX80 CLUTCH/KIC KSTARTER/G EARSHIFT LINKAGE CLUTCH PLATE INSPECTION Check for plate warpage on a surface plate, using a feeler gauge. SERVICE LIMIT: 0.20 mm (0.008 in) CLUTCH OUTER INSPECTION Check the slots in the outer drum for nicks, cuts or indentations made by the friction discs.
  • Page 75 �HONDA � MBXSO· MBX80 CLUTCH/KICKSTARTER/GEARSHIFT LINKAGE (1) PRIMARY DRIVE GEAR PRIMARY DRIVE GEAR REMOVAL Remove the left crankcase cover. Hold the flyweel with the UNIVERSAL HOLDER and remove the 12 mm nut, drive gear, and collar. NOTE Use the UNIVERSAL HOLDER to prevent the crankshaft from being turned during oper­...
  • Page 77 �HONDA � MBX50· MBX80 CLUTCH/KICKSTARTER/GEARSHIFT LINKAGE BALANCER TIMING/ ( 1) (2) INDEX MARK CLUTCH INSTALLATION BALANCER IDLER GEAR ( 1) Align the punch mark on the primary drive gear with the index mark on the crankcase. (4) INDEX MARK (2) Align the line on the balancer gear with the index mark on the crankcase.
  • Page 80 �HONDA � MBXSO· MBX80 CLUTCH/Kl CKSTARTE R/G EARSH I FT LINKAGE Measure the kick idler gear I.D. SERVICE LIMIT: 15 . 1 00 mm (0.5945 in) Measure the countershaft 0.D. SERVICE LIMIT: 14.940 mm (0.5882 in) Calculate the clearance between the gear and shaft.
  • Page 81 �HONDA � MBX50· MBX80 CLUTCH/KICKSTARTER/GEARSHIFT LINKAGE (1) RATCHET GUIDE PLATE Install the kickstarter in the crankcase with the drive ratchet resting against the guide plate stopper as shown. (2) DRIVE RATCHET (1) RATCHET GUIDE PLATE Install the kick return spring.
  • Page 82 CLUTCH/KlCKSTARTER/GEARSHIFT LINKAGE DRUM CAIVl PLATE Remove the bolt attaching the drum cam plate and remove the plate and roller pins. (2) BOLT Remove the change pedal and withdraw the shift spindle INSPECTION (3) SHIFT RETURN (1) SHIFT ARM SPRING Perform the following operations: SPRING /·...
  • Page 83 CLUTCH/KICKSTARTER/GEARSHI FT LINKAGE INSTALLATION Installation of the shift linkage is the reverse order of removal. Install the shift spindle and change pedal. Tighten the change pedal bolt to the specified torque. TORQUE: 8-12 N.m (0.8-1.2 k g -m , 6-9 ft-lb) (1) SHIFT SPINDLE (2) CHANGE PEDAL (1) ROLLER PIN...
  • Page 85 �HONDA � MBX50·MBX80 ALTERNATOR SERVICE INFORMATION ALTERNATOR REMOVAL ALTERNATOR INSTALLATION...
  • Page 86 �HONDA � MBX50· MBXSO ALTERNATOR SERVICE INFORMATION GENERAL INSTRUCTIONS ., The alternator can be serviced without removing it from the motorcycle. Do not remove the pulse generator from the stator base ., For alternator inspection, refer to Section 15. TOOLS...
  • Page 87 ALTERNATOR AUER R REMOVAL ('I) LEFT CRANKCASE COVER On the Deluxe model, remove the under cowl (Page 14-3). Remove the flange bolts and remove the left c rank­ case cover. (1) UNIVERSAL HOLDER Remove the 12 mm nut attaching the flywheel. ROTOR (2) ALTERNATIOR ROTOR (FLYWHEEL) PULLER...
  • Page 88 �HONDA. � MBXSO· MBX80 ALTERNATOR (1) CONNECTORS Disconnect the alternator wire connectors anc;l neutral switch wire. (1) NEUTRAL SWITCH WIRE Disconnect the netural switch wire from the switch. NOTE Do not remove the netural switch. Oil will flow out when the switch is removed.
  • Page 89 HONDA � MBX50· MBXSO ALTERNATOR ALTERNATOR INSTALLATION (1) INDEX MAR K Install the stator. NOTE Install the stator with the line aligned with the index mark on the crankcase. ( 2) STATOR (3) ALIGNMENT LINE (1) CONNECTORS Connect the alternator and neutral switch wires.
  • Page 90 �HONDA. � MBXSO· MBX:80 ALTERNATOR After installing the flywheel, start the engine and inspect the ignition timing (Page 3-6). (1) LEFT CRANKCASE COVER Install the left crankcase cover. NOTE Make sure that the alternator and neutral <1> switch wires are not interfering with the flywheel.
  • Page 91 CRANKSHAFT/ �HONDA TRANSMISSION � MBX50•MBX80 � '.@�...
  • Page 92 W\HON'DA � MBX50· MBX80 CRANKSHAFT/TRANSMISSION 9- 2 SERVICE INFORMATION TROUBLESHOOTING CRANKCASE SEPARATION TRANSMISSION DISASSEMBLY 9 -8 CRANKSHAFT REMOVAL 9-11 CRANKSHAFT INSTALLATION 9-12 GRANSMISSION ASSEMBLY 9-13 CRANKCASE ASSEMBLY...

  • Page 93: Cylinder Head

    HON'D.A MBX50·MBX80 CRAN KS HAFT /TRANSMISSION SERVICE INFORMATION GENERAL INSTRUCTIONS • This section includes transmission and crankshaft repairs which require crankcase separation. • The following parts must be removed before disassembling the crankcase. • Oil pump See section 2 • Cylinder head/cylinder/piston See section 6 •...
  • Page 96 W\HONDA. � MBXSO· MBX80 CRANKSHAFT/TRANSMISSION SHIFT FORK/SHIFT FORK SHAFT/ SHIFT DRUM INSPECTION Check each shift fork for wear, bending or any other faults. Measure the and shift claw thick­ 1.0. ness. SERVICE LIMITS: Claw thickness: 4.50 mm (0.177 in) I.D.: 10.50 mm (0.396 in)
  • Page 97 W\HONDA. � MBX50· MBXSO CRANKSHAFT/TRANSMISSION (1) MAINSHAFT (2) COUNTERSHAFT TRANSMISSION REMOVAL Remove the mainshaft and countershaft. TRANSMISSION INSPECTION Check gear dogs, dog holes and teeth for excessive or abnormal wear, or evidence of insufficient lubri­ cation. (1) COUNTERSHAFT (2) MAINSHAFT @��...
  • Page 98 �HONDA � MBX50· MBX80 CRANKSH AFT/TRA NSMISSIO N (1) COUNTERSHAFT Measure the O.D. of the mainshaft and counter­ shaft. SERVICE LIMITS: A: 16.93 mm (0.667 in) B: 16.44 mm (0.647 in) C: 18.93 mm (0. 745 in) D: 19.43 mm (0.765 in)
  • Page 99 �HONDA � MBXSO· MBXSO CRANKSHAFT /TRANSMISSION Drive in the bearings with the following common and special tools. Balancer weight left bearing: e Driver A e Attachment 32 x 35 mm e Pilot 12 mm Mainshaft right and countershaft left bearings: •...
  • Page 101 �HONDA � MBXSO· MBX80 CRAN KS HAFT /TRAN SM ISSI ON CRANKSHAFT BEARING INSPECTION ,-- - -• ! Spin the crankshaft bearing by hand and check for PLAY play. The bearing must be replaced if it is noisy or has excessive play.
  • Page 102 �HONDA � MBXSO· MBX80 CRANKSHAFT/TRANSMISSION (1) DRIVER A Drive new right crankshaft bearing and oil seal with the following common tools. Right crankshaft bearing: • Drive A • Attachment 52 x 55 mm • Pilot 25 mm Right crankshaft oil seal •...
  • Page 103 �HONDA � MBX50· MBXSO CRAN l<SHAFT /TRANSMISSION (1) CRANKSHAFT Install the crankshaft in the right crankcase. Use a special tool "CRANKSHAFT ASSEMBLY TOOL (07965-1660100)" if it is hard to install the crankshaft to the right crankcase. NOTE Apply clean 2-cycle engine oil to the journal and crankpin bearings.
  • Page 104 HONDA � MBX50· MBX80 CRANKSHAFT/TRANSMISSION (1) MAINSHAFT (2) COUNTERSHAFT Install the mainshaft and countershaft in the right crankcase. (1) SHIFT FORK SHAFT Install the shift drum, shift froks and shift fork shaft. Position the shift drum in neutral as shown.
  • Page 105 �HONDA � MBXSO· MBX80 CRAN KS HAFT/TRANSMISSION (1) LEFT CRANKCASE Place the left crankcase onto the right crankcase . (2) RIGHT CRANKCASE Tighten the crankcase bolts in a crisscross pattern. Install the drive sprocket. (3) DRIVE SPROCKET 9-14...
  • Page 106 �HONDA � MBXSO· MBX80 8-12 N.m ft-lb) (0.8-1.2 kg-m, (1) WATER P UMP SHAFT BUSHING 10-0...
  • Page 107 �HONDA � MBX50·MBX80 COOLING SYSTEM SERVICE INFORMATION 10-2 TROUBLESHOOTING 10-2 RADIATOR COOLANT 10-3 RADIATOR 10 -4 WATER PUMP 10-6 THERMOSTAT/TEMPERATURE SENSOR 10-9 10-1...
  • Page 108 ( ;;;;J}\ HONDA � MBX50· MBXSO COOLING SYSTEM SERVICE INFORMATION GENERAL INSTRUCTIONS e To service the master pump mechanical seal, remove the left crankcase cover. All cooling system services can be done with the engine in the frame. Do not remove the radiator cap when the engine is hot. The coolant is under pressure and it could result in scaling. The engine must be cool before sevicing the cooling sytem.
  • Page 109 �HONDA � MBXSO· MBX80 COOLING SYSTEM RADIATOR COOLANT (1) RADIATOR CAP COOLANT CHANGE Engi,ne must be cool before servzczng the cooling system, or severe scalding may result. On the Deluxe model, remove the under cowl (Page 14-3). Remove the seat, side covers and fuel tank.
  • Page 110 �HONDA. � MBXSO· MBX80 COOLING SYSTEM RADIATOR (1) FUEL TANK REMOVAL Remove the seat, side covers and fuel tank. On the Deluxe model, remove the under cowl (Page 14-3). Remove the radiator cap. Remove the coolant drain bolt and rain the coolant.
  • Page 111 HONDA MBX50•MBX80 COOLING SYSTEM INSPECTION Inspect the radiator soldered joints and seams for leaks. Blow diret out from between core fins with com­ pressed air. If insects, etc., are clogged the radiator, wash them off with low pressure water. (1) RADIATOR CAP Pressure test the radiator cap.
  • Page 112 �HONDA. � MBX50· MBX80 COOLING SYSTEM WATER PUMP 1 (1) WATER PUMP COVER REMOVAL Drain the radiator coolant (Page 10-3). Remove the water pump cover bolts and cover. (2) RADIATOR HOSES (1) IMPELLER Remove the cap nut, copper washer, impeller and plain washer from the water pump shaft.
  • Page 113 �HONDA. � MBX50·MBX80 COOLING SYSTEM (1) IMPELLER (2) SEALING PLATE INSPECTION Check the mechanical seal for damage or deteriora­ tion. Check the water pump shaft bearing in the right crankcase cover for excessive play or damage. (3) MECHANICAL SEAL Check the water pump shaft for bent or other damage.
  • Page 114 HONDA MBX50,MBX80 COOLING SYSTEM ( 1) DRIVER A Drive a new mechanical seal with the following special and common tools. e Driver A e Mechanical seal driver 07945-4150400 I nstal I a new oi I seal. Drive a new bearing into the right crankcase cover with the following special and common tools.
  • Page 116 �HONDA � MBXSO,MBX80 COOLING SYSTEM THERMOSTAT INSPECTION (1) THERMOSTAT Inspect the thermostat visually for damage. Suspend the thermostat in heated water to chech: its operation. ( 2) THERMOMETER Do not let the thermostat or thermometer touch the pan or false readings will result.
  • Page 117 HONDA FRONT WHEEL/SUSPENSION MIX50•MBX80 24-30 N.m (2.4-3.0 kg·m, 17-22 ft·lb) 24-30 N.m (2.4-3.0 kg-m, 17-22 ft-lb) 11-0...
  • Page 118 HONDA � MBX50· MBX80 FRONT WHEEL/SUSPENSION SERVICE INFORMAT ION 11-2 GROUBLESHOOTING 11-3 HEADLIGHT 11-4 INSTRUMENT S 11-5 HEAD LE BAR 11-7 FRONT WHEEL 11-9 FRONT FORK 11-13 STEERING STE M 11-19 11-1...
  • Page 119 �HONDA � MBXSO· MBX80 FRONT WHEEL/SUSPENSION SERVICE INFORMATION e A jack or other support is required to support the motorcycle. e Never ride on the rim or try to bend the wheel. TOOLS Special 07917-3230000 HEX Wrench 6 mm 07944-1150001...
  • Page 120 �HONDA. � MBX50· MBX80 FRONT WHEEL/SUSPENSION TROUBLESHOOTING Hard steering Hard suspension 1. Insufficient tire pressure 1. Incorrect fluid weight in front forks 2. Steering adjustment nut too tight Front suspension noise 3. Damaged steering stem bearings 1. Slider binding 4. Damaged steering ball races or cone races 2.
  • Page 121 �HONDA. � MBX50·MBX80 FRONT WHEEL/SUSPENSION HEADLIGHT REMOVAL On the Deluxe model, remove the fairing (Page 14-2). On the Standard model, remove the four headlight case mounting bolts and headlight case. Remove the headlight mounting bolts and headlight . Disconnect the headlight coupler and position I ight connectors.
  • Page 122 �HONDA � MBX50· MBX80 FRONT WHEEL/SUSPENSION INSTALLATION Align the alignment marks on the headlight with the index marks on the bracket. (1) Align (1) BULB HOLDERS INSTRUMENTS INDICATOR AND METER BULB RE­ PLACEMENT Remove the headlight. REMOVAL/INSTALLATION Remove the headlight (Page 11-4).
  • Page 123 �HONDA � MBXSO· MBX80 FRONT WHEEL/SUSPENSION DISASSEMBLY Remove the two instrument cover screws. Remove the four instrument lower cover scrws and separate the instruments. (3) TEMPERATURE (1) TACHOMETER (2) SPEEDOMETER GAUGE Remove the screws attaching each instrument and remove the tachometer, speedometer and tempera­...
  • Page 125 HONDA MBXSO,MBX80 FRONT WHEEL/SUSPENSION INSTALLATION (1) PUNCH MARK Place the handlebar onto the lower holder by aligning the punch mark with the upper face of the lower holder. Place the upper holders on the hndlebar with the punch marks facing the front.
  • Page 126 �HONDA � MBXSO· MBXSO FRONT WHEEL/SUSPENSION FRONT WHEEL REMOVAL Remove the axle nut. Raise the front wheel off the ground by placing a block or safety stand under the engine. (1) AXLE NUT Disconnect the speedometer cable. Remove the axle shaft and front wheel.
  • Page 127 HONDA � MBXSO· MBXSO FRONT WHEEL/SUSPENSION WHEEL BEARING INSPECTION (1) RADIAL Check the wheel bearing by placing the wheel on a truing stand and spinning the wheel by hand. - - -11--- ----"- - P LAY Replace the bearing with a new one if it is noisy or shows excessive play.
  • Page 129 �HONDA � MBXSO· MBX80 FRONT WHEEL/SUSPENSION FRONT WHEEL INSTALLATION Position the front wheel between the fork legs and insert the axle from the right side. Position the speedometer gearbox as shown. Connect the speedometer cable to the speedo­ meter gearbox.
  • Page 130 �HONDA. � MBXSO· MBXSO FRONT WHEEL/SUSPENSION FRONT FORK REMOVAL Remove the front wheel (Page 11-9). Remove the brake caliper. Remove the fron fender. NOTE Do not loosen the brake hose unless it is absolutely necessary. If the hose is loosened or disconnected, the brake system must be bled.
  • Page 131 �HONDA. � MBX50· MBX80 FRONT WHEEL/SUSPENSION DISASSEMBLY (1) FORK INNER BOLT Remove the inner bolt. NOTE • Hold the fork tube in a vise with rag or soft jaws avoiding the sliding surface as shown. CAUTION The inner bolt is under spring pressure. Cover...
  • Page 132 �HONDA � MBX50· MBXSO FRONT WHEEL/SUSPENSION Remove the socket bolt. Remove the fork tube, piston, rebound spring and oi I lock piece. CAUTION Do not distort the slider in a vise. (1) 6 mm HEX WRENCH 07917-3230000 FORK TUBE RUNOUT Place the fork tube in V blocks and read the runout.
  • Page 133 �HONDA � MBX50· MBX80 FRONT WHEEL/SUSPENSION SLIDER/PISTON INSPECTION Check the slider for score marks, scratches or abnormal wear. (2) PISTON ASSEMBLY NOTE Wash all removed parts in solvent and wipe them off thoroughly before assembly. FORK BOLT (9) DUST (10) SEAL �...
  • Page 134 �HONDA � MBX50· MBX80 FRONT WHEEL/SUSPENSION Install the piston ring on the piston. Install the frok tube rebound spring and piston. Install the oil lock piece. Apply locking agent to the socket bolt threads and underside on the bolt. NOTE "' To tighten the socket bolt, it may be neces­...
  • Page 135 {:;jj\ HONDA � MBX50· MBXSO FRONT WHEEL/SUSPENSION (1) FORK INNER BOLT Install and torque the fork inner bolt. TORQUE: 15-30 N.m (1.5-3.0 kg-m, 11-22 ft-lb) NOTE Hold the fork tube in a vise, avoiding the sliding surface. INSTALLATION Install the front forks.
  • Page 136 �HONDA � MBX50· MBXSO FRONT WHEEL/SUSPENSION (1) HEADLIGHT BRACKET STEERING STEM REMOVAL Remove the headlight (Page 11-4). Remove the instruments (Page 11-5). Remove the front wheel (Page 11-9). Remove the headlight case bracket. Remove the handlebar (Page 11 · 7).
  • Page 138 �HONDA � MBXSO· MBX80 FRONT WHEEL/SUSPENSION Install the top bridge. Install the fron forks (Page 11-18). Tighten the stem nut. TORQUE: 60-90 N.m (6.0-9.0 kg-m, 43-65 ft-lb) Install the removed parts in the reverse order of removal. (1) STEM NUT...
  • Page 139 HYDRAULIC BRAKE 12. �HONDA. � MBX50•MBX80 10-14 N.m (1.0-1.4 kg-m, 7-10 ft-lb) 25-35 N.m (2.5-3.5kg-m, 18-25 ft-lb) 15-20 N.m ( 1.5-2.0 kg-m, 24-30 N.m (2.4-3.0 kg-m, 17-22 ft-lb) 11-14 ft-lb) 12-0...
  • Page 140 �HONDA � MBXSO· MBX80 HYDRAU UC BRAKE 12-2 SERVICE INFORMATION 12-2 GROUBLESHOOTING BRAKE FLUID/AIR BLEEDING 12-3 12-4 BRAKE PAD/DISC BRAKE CALIPER 12-6 BRAKE MASTER CYLINDER 12-9 12-1...
  • Page 141 �HONDA � MBXSO· MBXSO HYDRAULIC BRAKE SERVICE INFORMATION GENERAL INSTRUCTIONS • The front brake pads can be replaced without disconnecting the brake hose .. Once the hydraulic system has been opened, or if the brake feels sraongy, the system must be bled.
  • Page 143 �HONDA �MBX50·MBX80 HYDRAULIC BRAKE BRAKE PAD/DISC (1) GROOVE BRAKE PAD INSPECTION The front brake pads require replacement if the groove in the sides of the pads reaches the edges of the brake disc. (2) GROOVE (3) BRAKE PADS BRAKE PAD REPLACEMENT NOTE Do not disconnect the brake hose when re­...
  • Page 145 �HONDA � MBX50· MBX80 HYDRAULIC BRAKE BRAKE CALIPER REMOVAL Remove the pin bolt cap and loosen the pin bolts. Remove the two bolts attaching the caliper and remove the caliper from the fork leg. Remove the bracket from the cliper.
  • Page 146 �HONDA � MBX50· MBX80 HYDRAULIC BRAKE (1) PISTON SEALS Remove the p in boots. Lift out the p iston and dust seals b y first p ushin g them into the c y linder. Clean the cali p er g rooves with brake fluid.
  • Page 147 �HONDA � MBX50· MBXSO HYDRAULIC BRAKE ASSEMBLY Wash all the removed parts. Coat the piston and dust seals with silicone grease. Lubricate the inside diameter of the caliper cylinders with brake fluid and install the pistons with the concave end on the brake pad side.
  • Page 148 �HONDA � MBXSO· MBXSO HYDRAULIC BRAKE INSTALLATION Install the brake hose and seal washer. TORQUE: 25-35 N.m (2.5-3.5 kg-m, 18-25 ft-lb) Install the bracket to the caliper. Install and tighten the caliper bracket to the front fork to the specified torque.
  • Page 149 {:;;jjj\ HONDA � MBX50· MBXSO HYDRAU-LIC BR_ A KE (1) S PRING (2) DIAPHRAGM Remove the reservoir from the master cylinder. Clean the master cylinder and reservoir in brake fluid. (3) SNAP RING (4) MASTER PISTON INSPECTION Check the master cylinder for score marks, scratches or other defects.
  • Page 151 REAR WHEEL/BRAKE/ �HONDA SUSPENSION � MBX50· MBX80 27-33 N.m (2.7-3.3 kg-m 20-24 ft-lb) 70-85 N.m (7.0-8.5 kg-m 51-62 ft-lb) 27-33 N.m (2.7-3.3 kg-m, 40-50 N.m 20-24 ft-lb) (4.0-5.0 kg-m, 18-25 N.m 9-36 ft-lb) ( 1.8-2.5 kg-m , 13-18 ft-lb) 13-0...
  • Page 152 �HONDA � MBX50· MBX80 REAR WHEEL/BRAKE/SUSPENSION SERVICE INFOR M ATION 13-2 TROUBLESHOOTING 13-2 REAR WHEEL 13-3 REAR BRAKE 13-6 REAR SHOCK ABSORBER 13-9 REAR SHOCK ABSORBER LINKAGE 13-11 L _ _ _ _ M _ ______________ sw __ _ __ _...
  • Page 153 (:;;jf\ HONDA � MBXSO, MBX80 REAR WHEEL/BRAKE/SUSPENSION SERVICE INFORMATION GENERAL INSTRUCTIONS • Do not remove rivets, nuts and pins from the rim, spoke plate and hub. • Never ridte on the rim or try to bend wheel. TOOLS Special 07967-G E20000...
  • Page 154 �HONDA � MBX50· MBXSO REAR WHEEL/BRAKE/SUSPENSION REAR WHEEL (1), CHAIN ADJUSTING NUT (2) AXLE NUT REMOVAL Remove the brake rod. Remove the cotter pin and disconnect the torque link. Remove the axle nut. Loosen the lock nut and chain adjusting nut.
  • Page 155 � MBX50· MBX80 REAR WHEE LIBRA KE/SUSPENSION REAR WHEEL RIM RUNOUT INSPEC­ TION Check the rim for runout by placing the wheel in a truing stand. Spin the wheel by hand and read the runout using a dial indicator gauge.
  • Page 157 W'\HONDA � MBX50, MBX80 REAR WHEEL/BRAKE/SUSPENSION (1) CHAIN (2) GRADUATED (3) INDEX ADJUSTER SCALE MARK Install the brake rod and brake torque link. TORQUE: 18-25 N.m (1.8-2.5 kg-m, 40-51 ft-lb) Adjust the drive chain tension (Page 3-11 ). CHAIN SLACK: 10-20 mm (3/8-3/4 in)
  • Page 158 2HONDA. � MBXSO· MBX80 REAR WHEEL/BRAKE/SUSPENSION REAR BRAKE SHOE REPLACEMENT Remove the brake shoes. Replace the brake shoes with new ones. BRAKE CAM DISASSEMBLY Remove the brake arm. Remove the indicator plate. Remove the brake cam. Remove the felt ring. Clean the shoe contacting faces of the brake cam.
  • Page 159 HONDA MBX50·MBX80 REAR WHEEL/BRAKE/SUSPENSION BRAKE PEDAL (1) BRAKE ARM (2) BRAKE ROD Remove the exhaust pipe. Remove the brake rod. (3) ADJU . S TING NUT (1) RETURN SPRING Remove the brakelight switch spring. Remove the return spring. Remove the c otter pin, plain washer, then remove the brake pedal.
  • Page 160 �HONDA � MBXSO· MBXSO REAR WHEEL/BRAKE/SUSPENSION REAR SHOCK ABSORBER (1) UPPER MOUNTING BOLT REMOVAL Remove the seat, side covers and fuel tank. Raise the wheel off the ground by placing a block under the engine. Remove the shock absorber upper and lower mount­...
  • Page 161 HONDA. MBX50·MBX80 REAR WHEEL/BRAKE/SUSPENSION REAR DAMPER INSPECTION Check the rear damper for damage or fluid leaks. (1) REAR DAMPER SPRING FREE LENGTH Measure the spring free lenght. SERVICE LIMIT: 135 mm (5.3 in) .._ __ (1) FREE LENGTH ---i (1) SPRING SEAT...
  • Page 162 �HONDA � MBXSO· MBXSO REAR WHEEL/BRAKE/SUSPENSION (1) UPPER MOUNTING INSTALLATION BOLT Install the shock absorber I ower mount on the shock absorber linkage. Align the shock absorber upper mount with the frame while moving the rear wheel up and down and install the upper monting bolt.
  • Page 163 {:;;jjj\ HONDA. � MBXSO, MBX80 REAR WHEEL/BRAKE/SUSPENSION Raise the rear wheel off the ground by placing a block under the engine. Remove the rear shock absorber lingage pivot bolts and nuts and remove the linkage. Check the linkage bushings and collar for wear or damge.
  • Page 164 �HONDA � MBX50· MBX80 REAR WHEEL/BRAKE/SUSPENSION SWINGARM (1) SHOCK LINKAGE MUD GUARD REMOVAL Remove the rear wheel (Page 13-3). Remove the drive chain cover. Remove the shock linkage mud guard from the linkage. Remove the swingarm-to-shock absorber linkage bolt. Remove the swingarm pivot bolt and the swingarm.
  • Page 165 14-0...
  • Page 166 �HONDA. � MBX50· MBX80 FAIRING/UNDER COWL 14-2 FAIRING 14-3 UNDER COWL 14-1...
  • Page 167 2HON'DA � MBXSO· MBX80 FAIRING/UNDER COWL FAIRING (1) FAIRING Remove the three fairing mounting screws and the fairing. (2) SCREWS Remove the four bolts attaching the fairing bracket and bracket. (1) FAIRING BRACKET Install the fairing in the reverse order of removal. 14-2...
  • Page 168 �HONDA � MBXSO· MBX80 FAIRING/UNDER COWL UNDER COWL (1) SCREWS Remove the four screws mounting the under cowl and the under cowl. (2) UNDER COWL Remove the bolts attaching the under cowl brackets. and brackets. (1) UNDER COWL BRACKETS Install the under cowl in the reverse order of re­...
  • Page 170 �HONDA. � MBX50· MBXSO BATTERY/CHARGING SYSTEM SERVICE INFORMATION 15-2 15-2 TROUBLESHOOTING 15-3 BATTERY CHARGING SYSTEM 15-5 15-1...
  • Page 171 Specific gravity 1.280/20 C (68 Charging rate 0.3 amperes maximum 2,000 min- 1 (rpm) maximum Alternator Charging speed MBX50: 4,000 min - 1 (rpm) 8,000 min - 1 (rpm) Capacity O.BA min. (17.7V) Lighting switch OFF 2.5A max. (18.2V) Lighting switch ON 0.5A min.
  • Page 172 �HONDA � MBXSO· MBXSO BATTERY/CHARGING SYSTEM (1) NEGATIVE BATTERY WIRE (2) POSTIVE WIRE REMOVAL Remove the right side cover. Open the battery holder. Disconnect the negative and positive wires at the connectors. Remove the battery. (3) BATTERY HOLDER TESTING SPECIFIC GRAVITY Test each cell with a hydrometer.
  • Page 173 HONDA MBX50,MBX80 BATTERY/CHARGING SYSTEM CHARGING Connect the charger positive (+) cable to the battery positive (+) terminal. Connect the carger negative (-) cable to the bat­ tery nagative (-) terminal. Charging current: 1.4 amperes max. Charging: Charge the battery until specific gravity is 1.270- °...
  • Page 174 HONDA � MBXSO· MBX80 BATTERY/CHARGING SYSTEM (1) REG ULATOR/ RECTIFIE R (2) IGNITIO N CHARGING SYSTEM SWITCH ( 4) DIMMER SWITCH (5) LIGHT ING SWITCH 4.0 Ohm (13) LICENCE LIGHT 12V 5W (8) ALTERNATOR 12V 35/35W INDICATOR (12) METER LIGHT 12V 3.4W x 2 12V 1.7W...
  • Page 175 �HONDA � MBXSO· MBXSO BATTERY / CHARGING SYSTEM ALTERNATOR INSEPCTION Warm up the engine. Stop the engine. Disconnect the alternator connectors. Check the resistances betweeen the connectors. Yellow - Green: 0.1-1.0 Ohms White - Green: 0.3-1.5 Ohms Replace the stator and flywheel as a set if not within the specifications.
  • Page 176 �HONDA � MBX50· MBX80 BATTERY/CHARGING SYSTEM RESISTOR INSPECTION (1) RESISTOR Remove the fuel tank. Disconnect the resistor connectors. Measure the resistance between the connectors. Pink - Green: 4 ohms Green/White - Green: 6.7 ohms 15-7...
  • Page 177 SYSTE 1 6 . HONDA MBXSO·MBX80 (2) IGNITION (3) CDI COIL UNIT ( 1) SPAR KP LUG ·\ /� ,1.-: --- ( 4) ALTERNATOR (7) IGNITION SWITCH -- - -- -- -1 ( 4) ALTER NATOR (2) IGNI TION COIL (8) DIODE /�...
  • Page 178 �HONDA � MBX50· MBX80 IGNITION SYSTEM SERVICE INFORMATION 16-2 TROUBLESHOOTING 16-2 16 -3 IGNITION COi L CID UNIT 16-4 ALTERNATOR EXCITOR COIL/PULSE GENERATOR 16-4 16-1...
  • Page 179 � MBX50· MBXSO IGNITION SYSTEM SERVICE INFORMATION GENERAL • A CDI IGNITIO N SYSTEM is used and no adjustments are to be made. If the timing is incorrect, inspect the CDI unit and alternator and replace any defective parts.

  • Page 180: Ignition Coil

    �HONDA. � MBX.50· MBX.80 IGNITION SYSTEM (2) IGNITON IGNITION COil (1) PRIMARY COIL REMOVAL Remove the seat and fuel tank. Disconnect the wire leads. Remove the coil by removing the attaching bolts. Remove the spark plug cap by rotating it by hand.

  • Page 181: Ignition System

    HONDA MBX50,MBX80 IGNITION SYSTEM CDI UNIT I GN REMOVAL Remove the fuel tank. Remove the COi unit from the coupler. INSPECTION Measure the resistances between the terminals. Replace the COi unit with a new one if the read­ ings do not fall within the limits shown in the table.
  • Page 182 17. SWITCHES �HONDA � MBXSO· MBX80 SERVICE INFORMATION 17-2 IGNITION SWITCH 17-3 HANDLEBAR SWITCHES 17-3 BRAKE LIGHT SWITCHES 17-4 NEUTRAL SWITCH 17-4 01 L LEVEL SENSOR 17-5 17-1...
  • Page 183 (:;i!J\ HONDA � MBX50· MBX80 SWITCHES SERVICE INFORMATION GENERAL • Some wires nave different colored bands around them near the connector. These are connected to other wires which respond with the band color. • All plastic plugs have locking tabs that must be released before disconnecting, and must be aligned when reconnecting.

  • Page 184: Handlebar Switches

    HONDA MBX50·MBX80 SWITCHE S IGNITION SWITCH (1) IGNITION SWITCH Remove the headlight. Disconnect the ignition switch connectors. Check continuity of_ terminals on the coupler in each switch position. SWITCH POSTION OFF: B/W RtoB Terminal Postions Color code Bk/W HANDLEBAR SWITCHES...
  • Page 185 �HONDA � MBXSO· MBX80 SWITCHES BRAKE SWITCHES FRONT BRAKE Remove the headlight. Disconnect the front brakelight switchf wires at the connectors. Check the brakelight switch for continuity with the fron brake applied. Replace the seitch if necessary. (1) REAR BRAKELIGHT SWITCH...
  • Page 186 HONDA MBX50,MBX80 SWITCHES Oil LEVEL SENSOR INSPECTION Remove the fuel tank. Disconnect the oil level sensor coupler and remove the sensor from the oil tank. Measure the oil level sensor resistance with empty float position. RESISTANCE: G/R to Bk: 5-15 ohm G to Bk: Measure the resistance·...
  • Page 187 1 8 . TROUBLESHOOTI C2f\ HONDA � MBXSO· MBX80 ENGINE DOES NOT START OR IS HARD TO START 14-1 ENGINE LACKS POWER 14-2 POOR PERFORMANCE AT LOW AND IDLE SPEEDS 14-3 POOR PERFORMANCE AT HIGH SPEED 14-4 POOR HANDLING 14-4...
  • Page 190 �HONDA � MBX50· MBX80 TROUBLESHOOTING CHECK PROBABLE CAUSE 9. Ch}ck oil level. Also check LEVEL IS TOO LOW OR T00-----(1) Transmissio oil level too high, oil for contamination HIGH resulting in lack of power (2) Transmission oil level too low...
  • Page 191 �HONDA � MBX50, MBX80 TROUBLESHOOTING POOR PERFORMANCE AT HIGH SPEED CHECK PROBABLE CAUSE IMPROPER-------------(1) Faulty alternator 1. Check ignition timing {2) Faulty CDI PROPER 2. oJonriect fuel tube at carburetor FUEL FLOW IS RESTRICTED-----(1) Lack of fuel in tank (2) Clogged fuel tank cap breather...
  • Page 192 �HONDA � MBX50•MBX80, MEMO...
  • Page 194 �HONDA � MBXSO· MBX80 MBXSO SPARK PLUG Bougie ZUNDKERZE FRONT STOPUGHT SWITCH Contacteur de stop du frein annt VOA DERER BREMSUCHT SC HALTER R FRONT TURN SIGNAL 12VIOW � � IGNITION SWITCH OIL PRESSURE SWITCH '. · ' __ 1;����...

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