Z50R HOW TO USE THIS MANUAL CONTENTS Sections 1 through 3 apply to the whole motorcycle, while sections 4 through 14 describe parts of the motorcycle, grouped according to location. 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 troubleshooting for the section. "he subsequent pages give detailed procedures for the section. If you don't know what the trouble is, go to section 15, TROUBLESHOOTING. This shop manual is based on the 1979 Z50R. Subsequent year models service procedures and data are given with addendums, beginning with section 16. ALL INFORMATION AND ILLUSTRATIONS 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. m Z z UJ < I O HONDA MOTOR CO., LTD. SERVICE PUBLICATIONS OFFICE GENERAL INFORMATION LUBRICATION INSPECTION AND ADJUSTMENT FUEL SYSTEM ENGINE REMOVAL & INSTALLATION CYLINDER HEAD/VALVE CYLINDER/PISTON CLUTCH/GEARSHIFT SPINDLE AC GENERATOR TRANSMISSION/CRANKSHAFT FRONT WHEEL/BRAKE/SUSPENSION REAR WHEEL/BRAKE/SUSPENSION SEAT & FUEL TANK IGNITION SYSTEM TROUBLESHOOTING '80-'81 ADDENDUM '82 ADDENDUM Date of Issue September, 1981 © Honda Motor Co., Ltd. HONDA Z50R MEMO Z50R 1 GENERAL INFORMATION - I GENERAL SAFETY 1-1 TOOLS 1-5 r. SERVICE RULES 1-1 WIRING DIAGRAM 1-6 i, SPECIFICATIONS 1-2 CABLE AND HARNESS i 7 n ROUTING TORQUE VALUES 1-4 MAINTENANCE SCHEDULE 1-8 n n n 6 l I f fi n n GENERAL SAFETY pZEEZSa___________ • If the engine must be running to do some work, make sure the area is well-ventilated. Never run the engine in a closed area. The exhaust contains poisonous carbon monoxide gas. • Gasoline is extremely flammable and is explosive under certain conditions. Do not smoke or allow flames or sparks in your work area. SERVICE RULES 1. Use genuine HONDA or HONDA recommended parts and lubricants or their equivalent. Parts that do not meet HONDA's design specifications may damage the motorcycle. 2. Use the special tools designed for this product. 3. Install new gaskets, O-rings, cotter pins, lock plates, etc. when reassembling. 4. When torquing bolts or nuts, begin with the larger diameter or inner bolt first, and tighten to the specified torque diagonally in 2—3 steps, unless a particular sequence is specified. 5. Clean parts in non-flammable or high flash point solvent upon disassembly. Lubricate any sliding surfaces before reassembly. 6. After reassembly, check all parts for proper installation and operation. 7. Use only metric tools when servicing this motorcycle. Metric bolts, nuts, and screws are not interchangeable with English fasteners. The use of incorrect tools and fasteners may damage the motorcycle. r r- Date of Issue : Sep. 1978 GENERAL INFORMATION Z50R SPECIFICATIONS Item Metric i English i Dimensions \ Overall length 1,300 mm 51.2 in Overall width 623 mm 24.6 in ' Overall height 860 mm 33.9 in Wheel base 895 mm 35.2 in ; Seat height 590 mm 23.2 in Foot peg height 220 mm 8.7 in Ground clearance 140 mm 5.5 in Dry weight 52 kg 1151b ; Frame t f L L I ] Type Backbone Front suspension Telescopic fork J Rear suspension Swing arm I Front tire size 3.50-8-2PR ! Rear tire size 3.50-8-2PR Cold tire pressures Front 1.0 kg/cm2 14 psi ; Rear 1.0 kg/cm2 14 psi Front brake Internal expanding shoe Rear brake Internal expanding shoe \ Fuel capacity 4.5 lit 1.19 US gal Fuel reserve capacity 1.0 lit 0.26 US gal Caster (Degrees from horizon tal) 25° Trail 42 mm 1.7 in i Front fork oil Grease i Engine Type Air-cooled, 4 stroke OHC Cylinder arrangement Single 80° inclined from vortical Bore and stroke 39.0x41.4 mm 1.535 x 1.630 in • Displacement 49 cm2 3.0 cu in | Compression ratio 8.8 x 1 Valve train Chain driven overhead camshaft Oil capacity 0.8 lit 0.21 US gal Lubrication system Forced and wet sump ¦ Cylinder head compression p ressure 12.0 kg/cm2 - -1,000 rpm | 168 psi Intake valve Opens 7° BTDC(at 1mm lift) Closes 12° ABDCIat 1mm lift) Exhaust valve Opens 22° BBDC(at 1mm lift) Closes 2° ATDC(at 1mm lift) Valve clearance (cold) IN 0.05 mm 0.002 in EX 0.05 mm 0.002 in Idle speed 1500± 100 rpm ' Engine dry weight 17 kg 37.5 lb ¦4 f% Date of Issue : Sep. 1978 HONDA. Z50R GENERAL INFORMATION 1 Item Metric English Carburetion Carburetor type Piston valve 1 Venturi diameter 11 mm 0.43 in Setting number PA03B [A] I 1 Air screw opening 1-1/2 i Float level 12.7 mm 0.50 in , Drive train Clutch Wet multi-plate automatic (centrifugal) ! Transmission 3-speed constant mesh ; j Primary reduction ratio 3,722 Gear ratio 1 3,181 Gear ratio II 1,823 , Gear ratio III 1,190 ' Gear ratio IV - 1 Gear ratio V - Final reduction ratio 3.083,37/12 Gear shift pattern Left foot operated return system N—1—2—3 Electrical Ignition Flywheel magneto Alternator Flywheel Starting system Kick start Spark plug U.S.A. type NGKC6H DENSO U20FS Canada type NGKCR6HS DENSOU20FSR-L i Spark plug gap 0.6-0.7 mm 0.024-0.028 in Date of Issue : Sep. 1978 GENERAL INFORMATION Z50R TORQUE VALUES ENGINE Item Q'ty Thread dia (mm) Torque kg-m (ft-lb) Valve adjusting hole cap 2 30 1.0~ 1.4 (7~ 10) Valve adjusting lock nut 2 5 0.7-1.1 (5~8) Cylinder head cover nut 4 8 0.9 ~ 1.2 (7~9) Cam sprocket bolt 3 5 0.8-1.2 (6-9) Cylinder bolt 1 6 0.8-1.2 (6-9) Left crankcase cover screw 3 6 0.7-1.1 (5-8) Flywheel nut 1 10 3.0-3.8 (22-27) Right crankcase cover screw 8 6 0.7-1.1 (5-8) Clutch outer nut 1 14 3.5-4.5 (25-33) Shift drum stopper bolt 1 6 0.9-1.4 (7-10) Dram plug 1 12 2.0-3.0 (15-22) Drive sprocket bolt 2 6 0.8-1.2 (6-9) FRAME Item Q'ty Thread dia (mm) Torque kg-m (ft-lb) Steering stem nut 1 24 6.0-8.0 (43-58) Fork top bridge bolt 2 10 1.8-2.5 (13-18) Front axle nut 1 12 3.5-5.0 (25-36) Rear axle nut 1 12 3.5-5.0 (25-36) Shock absorber nut 4 10 2.5-3.5 (18-25) Swing arm pivot ' .it 1 10 2.5-3.5 (18-25) Engine hanger bolt 2 8 2.0-2.5 (15-18) Driven sprocket bolt 3 8 1.8-2.3 (13-17) Torque specifications listed above are for the most important items. If a torque specification is not listed, follow the standards given below. STANDARD TORQUES Item Torque kg-m (ft-lb) Item Torque kg-m (ft-lb) 5 mm bolt, nut 0.45-0.6 (3.3-4.3) 5 mm screw 0.35-0.5 (2.5-3.6) 6 mm bolt, nut 0.8-1.2 (6-9) 6 mm screw 0.7-1.1 (5-8) 8 mm bolt, nut 1.8-2.5 (13-18) 6 mm flange bolt, nut 1.0-1.4 (7-10) 10 mm bolt, nut 3.0-4.0 (22-29) 8 mm flange bolt, nut 2.4-3.0 (17-22) 12 mm bolt, nut 5.0 - 6.0 (36 - 43) 10 mm flange bolt, nut 3.0-4.0 (22-29) -« M Date of Issue : Sep. 1978 Z50R GENERAL INFORMATION TOOLS SPECIAL TOOLS COMMON TOOLS Tool name Tool No. Tool name Tool No. Float level gauge 72401-0010000 Pin spanner, 36 mm 07902-0010000 Pin spanner 07702-0010000 Valve adjusting socket wrench 07908-0010000 Tappet adjusting (B) Tappet adjusting wrench 8x9 07708-0030400 07708-0030100 Lock nut wrench, 14 mm 07716-0010100 Flywheel holder 07925-0010001 Universal holder 07725-0010101 Flywheel puller 07933-0010000 Flywheel & Rotor puller 07733-0010000 Valve guide remover 07942-3290100 Valve guide remover (5.5 mm) 07742-0010100 Valve guide driver 07942-3290200 Valve guide driver (B) 07742-0020200 Bearing driver 07947-0450000 Bearing driver outer 32 x 35 Bearing driver pilot (12 mm) 07746-0010100 07746-0040200 Driver handle 07949-2860000 Bearing driver handle (A) 07749-0010000 Valve spring compressor 07757-0010000 Valve guide reamer 5.48 mm 07984-0980000 Clutch outer holder 07923-0400000 Universal holder 07725-0010101 Shock absorber compressor 07959-3290001 Ball race driver/remover 07944-1150001 Date of Issue : Sep. 1978 © HONDA MOTOR CO.. LTD. 1-5 GENERAL INFORMATION Z50R WIRING DIAGRAM CONTir UJ 0 0 3 reen I (J OPSWIT (D 0 0 ;k / White 1- Bla< UJ NGIN OFF RUN OFF Color LU 1-« Data of Issue : Sep. 1978 © HONDA MOTOR CO., LTD. Z50R GENERAL INFORMATION n CABLE AND HARNESS ROUTING r~ r", r .-»-*, r~ I * WIRE BAND THROTTLE CABLE WIRE HARNESS HIGH TENTION WIRE GNITTION COIL PRIMARRY LEAD Date of Issue : Sep. 1978 "1-7 GENERAL INFORMATION Z50R MAINTENANCE SCHEDULE The maintenance intervales shown in the following schedule are based upon average riding conditions. Machines subjected to severe use, or ridden in unusually dusty areas, require more frequent servicing. Items marked *should be serviced by an authorized Honda dealer, unless the owner has proper tools and is mechanically qualified. Other maintenance items may be serviced by the owner. CA UTION To maintain the safety and reliability of your HONDA motorcycle, do not modify the motorcycle and use genuine HONDA parts or their equivalent when servicing or repairing. The use of other replacement parts which are not of equivalent quality may impair the operation of your motorcycle. WARNING To prevent personal injury, always make certain the engine is stopped and the motorcycle is supported securely on a level surface prior to performing any maintenance. ^"\ FREQUENCY ITEM ^"~~\^ "INITIAL / , MONnA MOTOR CO \ TO r \r r~- i ¦ r~ c i i r f* Z50R MEMO Date of Issue • Sep 1978 *&***«--+*, :.<.;*;.v,;:.''• LUBRICATION HONDA. Z50R OIL PUMP — RIGHT CRANKCASE CYLINDER CYLINDER HEAD RIGHT CRANKCASE COVER CLUTCH ADJUSTING BOLT RIGHT CYLINDER HEAD SIDE COVER CENTRIFUGAL OIL FILTER CAMSHAFT — CRANKCASE CRANKSHAFT CRANKCASE 1 r\ Date of Issue ¦ Sep. 1978 r Z50R 2. LUBRICATION SERVICE INFORMATION TROUBLESHOOTING ENGINE OIL LEVEL ENGINE OIL CHANGE ENGINE OIL ROTOR FILTER/ SCREEN 2-1 OIL PUMP REMOVAL/ DISASSEMBLY 2-3 2-1 OIL PUMP INSPECTION 2-4 2-2 OIL PUMP ASSEMBLY/ 2-5 2-2 INSTALLATION 2-2 DRIVE CHAIN 2-5 LUBRICATION POINTS 2-7 SERVICE INFORMATIN GENERAL INFORMATION The oil pump can be disassembled with the engine in the frame. O r SPECIFICATIONS Forced and wet sump 0.8 lit (0.21 USqt) HONDA 4-STROKE OIL or an equivalent API service classification — SE Viscosity: General, all temperatures SAE 10W-40 Alternate Above 15°C (60°F) SAE 30 -10° -+15°C (15°-60°F) SAE 20 or 20W Above -10°C (15°F) SAE 20W-50 Below 0°C (32°F) SAE 10W STANDARD SERVICE LIMIT Outer rotor-to-body clearance Tip clearance 0.10-0.15 mm (0.004-0.006 in) 0.15 mm (0.006 in) 0.20 mm (0.008 in) 0.20 mm (0.008 in) Rotor-to-cover clearance 0.02-0.07 mm (0.001 -0.003 in) 0.12 mm (0.005 in) I r TROUBLESHOOTING Oil level tool low 1 Normal oil consumption 2 External oil leaks 3 Worn piston rings Low oil pressure 1 Plugged oil screen 2 Main oil pump worn High oil pressure 1 Plugged oil screen, gallery, or oil control orifice 2 Incorrect oil being used No oil pressure 1 Oil level too low 2 Oil pump shaft pin sheared or missing r Date of Issue . Sep. 1978 © HONDA MOTOR CO.. LTD. 2-1 LUBRICATION Z50R ENGINE OIL LEVEL Stop the engine and hold the motorcycle upright. Check the oil level with the filler cap/dipstick after 2—3 minutes. If the level is below the lower level mark on the dipstick, fill to the upper level mark. NOTE Do not screw in the cap when making this check ENGINE OIL CHANGE UPPER LEVEL MARK LOWER LEVEL MARK FILLER CAP DIPSTICK -jzzmxmzzzzzzzzzzizzzL DRAIN PLUG 2.0-3.0 kg-m (15-22 ft-lb) SPECIFIED LEVELi NOTE Drain the oil with the engine warm. Remove the oil filler cap dipstick and drain \ w plug, and drain the oil. Install the drain plug. Fill the crankcase with the recommended oil. Check the oil level with the filler cap/dipstick after 2—3 minutes. Install the oil filler cap. ENGINE OIL FILTER AND SCREEN Dram the engine oil. Remove the foot pegs and kick starter arm. Remove the right crankcase cover. Remove the clutch outer cover. CENTRIFUGAL FILTER CLEANING Clean the clutch outer cover and the inside of the clutch outer using a clean, lint-free cloth. NOTE Do not allow dust and dirt to 'enter the crankshaft oil passage. Do not use compressed air. OIL FILTER SCREEN CLEANING Remove the oil filter screen from the crankcase. Clean the filter screen. OIL FILTER SCREEN 2-2 Date of Issue : Sep. 1978 © HONDA MOTOR CO., LTD. HOINIDA Z50R LUBRICATION r OIL PUMP REMOVAL /DISASSEMBLY Drain the engine oil. Remove the kick starter pedal and foot pegs. Remove the right crankcase cover. Pull out the clutch lever, lifter, ball retainer and clutch cam. Remove the clutch outer cover and clutch assembly Remove the three oil pump mounting screws and oil pump. Remove the three cover screws and remove the oil pump cover. r r Pull out the pump shaft and remove the inner and outer rotors from the pump body. Date of Issue : Sep. 1978 o o LUBRICATION HONDA. Z50R OIL PUMP INSPECTION Check the inner and outer rotors. Replace as a set if damaged or scratched. Measure the pump tip clearance Measure the pump body clearance. Measure the pump side clearance. SERVICE LIMIT 0.2mm (0.008 in) SERVICE LIMIT 0.2mm (0.008 in) SERVICE LIMIT 0.12mm (0.005 O A Date of Issue : Sep. 1978 r Z50R LUBRICATION p r~> r n r OIL PUMP /ASSEMBLY INSTALLATION Install the outer and inner rotors into the pump body. Install the pump shaft. Install a new cover gasket. Secure the gasket and cover with the three screws. NOTE Make sure that the pump rotates freely. OIL PUMP INSTALLATION Install the oil pump with the gasket under it by aligning the rotor shaft with the groove of the cam chain guide spindle. DRIVE CHAIN NOTE Commercial aerosol type drive chain lubricants are recommended. Normally, drive chain lubrication is performed at the time of chain adjustment. Saturate each chain link joints so that the lubricant penetrates between the link plates, pins, bushings and rollers. 'm^mmm*****™* m Mb Date of Issue : Sep. 1978 -** unMnfl motor rn ! TD LUBRICATION HONDA. Z50R When the drive chain becomes extremely dirty, it should be removed and cleaned prior to lubrication. Carefully remove the master link retaining clip with a plier. Do not bend or twist the clip. Remove the master link. Remove the drive chain from the motorcycle. Clean the drive chain in non-flammable or high flash point solvent and brush, and allow to dry. Inspect the drive chain for possible wear or damage. Replace any chain that is excessively worn or damaged. Inspect the sprocket teeth for possible wear or damage. Replace if necessary. ~CA UTION~\ Never install a new drive chain on badly worn sprockets or a badly worn chain on new sprockets. Both chain and sprockets must be in good condition, or the new replacement chain or sprockets will wear rapidly. Lubricate the drive chain. Install the drive chain. For ease of assembly, hold the chain ends against adjacent rear sprocket teeth while inserting the master link. Install the master link retaining clip so that the closed end of the clip will face the direction of forward wheel rotation. Adjust the drive chain free play (Page 3-8). FREE PLAY: 15-25 mm (5/8-1 in) Check brake pedal free play and adjust, if necessary. 2-6 Date of Issue : Sep. 1978 © HONDA MOTOR CO., LTD ^,r"*u Z50R LUBRICATION LUBRICATION POINTS f l f r f i - Date of Issue : Sep. 1978 0_7 Z50R MEMO n«»« nf Iwie • Sep 1978 r^ Z50R 3 INSPECTION & ADJUSTMENT SERVICE INFORMATIONSPARKPLUG CONTACT BREAKER POINT/ IGNITION TIMING VALVE CLEARANCE CAM CHAIN TENSION THROTTLE OPERATION CARBURETOR IDLE MIXTURE 3-1 CABURETOR IDLE SPEED 3-5 ; CLUTCH 3-5 3-2 ! 3-2 AIR CLEANER 3-6 FRONT BRAKE 3-6 3-3 ! REAR BRAKE 3-7 3-4 DRIVE CHAIN 3-8 ' 3-4 ! 3-5 SPARK ARRESTER 3-8 h r SERVICE INFORMATION SPECIFICATIONS Spark plug gap 0.6-0.7 mm (0.024-0.028 in) Spark plug type USA type NGK: C6H ND: U20FS Canada type NGK: CR6HS ND: U20FSR- Valve clearance IN 0.05 mm (0.002 in) EX 0.05 mm (0.002 in) Contact breaker point gap 0.3-0.4 mm (0.012-0.016 in) Throttle free play 2-6 mm (1/8-1/4 in) Idle speed 1,500 ± 100 rpm Drive chain free play 15-25 mm (5/8-1 in) Front brake free play 10-20 mm (3/8-3/4 in) Rear brake free play 10-20 mm (3/8- -3/4 in) ! Tire pressure: Cold tire pressure Front 1.0 (14) kg/cm2 (psi) Rear 1.0 (14) Tire size ___Front Rear 3.50-8-2PR 3.50-8-2PR TORQUE VALUES Valve adjusting hole cap Valve adjusting screw lock nut Oil drain plug Rear axle nut 1.0-1.4 kg-m (7-10ft-lb) 0.7-1.1 kg-m (5-8 fMb) 2.0-2.5 kg-m (15-18 ft-lb) 3.5-5.0 kg-m (25-36 ft-lb) Date of Issue Sep 1978 ^¦ii^v Q-1 INSPECTION & ADJUSTMENT Z50R SPARK PLUG Disconnect the spark plug cap and remove the spark plug Visually inspect the spark plug electrodes for wear The center electrode should have square edges and the side electrode should not be eroded. Discard the spark plug if there is apparent wear or if the insulator is cracked or chipped. Measure the gap with a wire-type feeler gauge. Adjust the spark plug gap by carefully bending the side electrode. RECOMMENDED SPARK PLUG: U.S.A Type Canada Type NGK C6H CR6HS ND U20FS U20FSR-L Install the spark plug, tighten it by hand, then with a spark plug wrench. Connect the spark plug cap. CONTACT BREAKER POINT IGNITION TIMING IGNITION TIMING Remove the left crankcase cover. Inspect the contact point surfaces. If they are level but grayish in color or are slightly pitted, file or sand them lightly. If they have a noticable transfer of metal from one surface to the other, have evidence of heavy arcing, or are worn at an angle, the point set should be replaced. Adjust as follows: Disconnect the A. C. generator wires. Connect a continuity light to the black lead and to a battery positive terminal. Connect the battery negative terminal to a convenient frame ground. Rotate the flywheel counterclockwise and align the "F" mark with the crankcase index mark The timing is correct if the light becomes dim when both marks align. 0.6-0.7mm (0.024-0.028 in) CHECK : gap : deposit : dirt : wear CHECK : sealing : damage CHECK : damage : crack INDEX MARK BASE PLATE LOCKING SCREW "F"MARK BASE PLATE SCREWDRIVER o o Date of Issue : Sep. 1978 Z50R INSPECTION & ADJUSTMENT If the ignition timing is incorrect, loosen the contact breakter locking screw and adjust the breaker point gap. Increasing point gap will advance ignition timing. Decreasing the gap will retard ignition timing Tighten the locking screw and recheck the timing NOTE Replace the contact breaker points if the timing cannot be correctly adjusted while maintaining a minimum point gap of 0 3-0 4 mm (0 12-0.16 in). Connect the A C generator wires and install the left crankcase cover Use a stroboscopic timing light to determine accurate ignition timing. NOTE The "F" mark should align with the index mark at idle speed (1,500 rpm). VALVE CLEARANCE NOTE Inspect and adjust the valve clearance while the engine is cold (Below 35°C, 95° F) Remove the left crankcase cover and valve adjusting caps Rotate the flywheel counterclockwise and align the rotor "J" mark and crankcase index mark Before checking, make sure that the piston is at TDC (Top Dead Center) on the compression stroke (The rockers should be loose). Check the intake and exhaust valve clearances by inserting a feeler gauge between the adjusting screw and the valve stem. Adjust by loosening the lock nut and turning the screw until there is a slight drag on the feeler gauge. Tighten the clearance. lock nut and recheck the SERVICE LIMIT: 0.05 mm (0.002 in) (IN/EX) ADJUSTING SCREW LOCK NUT FEELER GAUGE VALVE ADJUSTING WRENCH 07908-0010000 Date of Issue • Sep. 1978 « MnND4 MOTOR CO I TD 3-3 INSPECTION & ADJUSTMENT HOIMDA Z50R CAM CHAIN TENSION Start the engine and allow it to idle. Loosen the 8 mm lock nut and adjusting bolt A one half turn. If the cam chain is still noise, remove the cap bolt. With adjusting bolt A still loosened, carefully screw in adjusting bolt B until the noise stops THROTTLE OPERATION Make sure that there is no deterioration, damage or kinks in the throttle cable, and that the throttle grip free play is 2-6 mm (1/8-1/4 in) at the outer edge of the throttle grip flange. Check for smooth throttle grip rotation from fully open to automatic full closing in all steering positions. Adjust or replace, if necessary. To adjust, turn the adjuster in either direction. ADJUSTING BOLT"B" 8mm LOCK NUT ADJUSTING BOLT "A" — CAP BOLT 2-6mm (1/8-1/4 in 3-4 Date of Issue : Sep. 1978 © HONDA MOTOR CO.. LTD Z50R INSPECTION & ADJUSTMENT CARBURETOR IDLE MIXTURE H NOTE The carburetor idle mixture adjustment should be made after the engine has obtained operating temperature, and with the transmission in neutral. Turn the throttle stop screw to obtain the lowest stable idle rpm. Turn the air screw clockwise until you hear the engine miss or decrease in speed, then counterclockwise until the engine misses or decreases in speed. Center the air screw exactly between these two extremes, at the point which produces the highest idle rpm. (Usually 1-1/2 turns out from the fully closed position). NOTE Turning the air screw in produces a rich fuel mixture. Turning the air screw out produces a lean fuel mixture. If the idle speed increases during mixture adjustment, readjust the throttle stop screw to reduce rpm. Adjust the idle speed to the specified rpm. CARBURETOR IDLE SPEED Turn the throttle stop screw to obtain the specified idle speed. IDLE SPEED: 1,500 ± 100 rpm CLUTCH Loosen the lock nut and turn the adjusting screw one full turn clockwise. Turn the screw counterclockwise until resistance is felt. Then turn the adjusting screw 1/8 to 1/4 turns clockwise. Tighten the lock nut. NOTE Hold the adjusting screw while tightening the lock nut. After adjusting the clutch, check its operation. CLUTCH DISENGAGEMENT The clutch should be disengaged when the gearshift pedal is depressed 14—18 mm (1/2-3/4 in) measured at the pedal end. 14-18mm (1 /2-3/4 in) ! | /// ^-— rp // /^^~~— ^$9-------~~ ^^^^ ] |i j i i i t I Date of Issue : Sep 1978 Q-* INSPECTION & ADJUSTMENT Z50R AIR CLEANER Remove the two screws and the air cleaner cover. Remove the air cleaner element. Wash the element in non-flammable or high flash point solvent and allow it to dry thor- ouly. Soak the element in clean gear oil (SAE 80-90). Squeeze out the excess oil. Reinstall the element and the cover. FRONT BRAKE Measure the front brake lever free play. FREE PLAY: 10-20 mm (3/8-3/4 in) • J J 10-20mm sAs (3/8-3/4 in) ^^^^ —-~"cc ^7 o.« Date of Issue : Sep, 1978 Z50R INSPECTION & ADJUSTMENT Adjust by turning the front brake adjusting r r r nut. REAR BRAKE Measure the rear brake pedal free play. FREETLAY: 10-20 mm (3/8-3/4 in) ^msm^m Adjust by turning the rear brake adjusting **>%|JfS|i*^ nut- , . . M I* steal, ¦V' " Date of Issue : Sep 1978 -^ uoMnfl Mrs-mo rn i xn 3-7 INSPECTION & ADJUSTMENT Z50R DRIVE CHAIN Place the motorcycle on a support block and shift the transmission into neutral. Check the drive chain free play. FREE PLAY: 15-25 mm (5/8-1 in) To adjust, loosen the axle nut. Turn both adjusting nuts an equal number of turns until the correct free play is obtained. NOTE | Be sure that the index mark aligns with the same scale graduation on both sides. Tighten the axle nut. TORQUE: 3.5-5.0 kg-m (25-36 ft-lb) Tighten the adjusting nuts after the axle nut has been tightened. SPARK ARRESTER Remove the diffuser pipe by removing the securing bolt. Remove the clean-out port lid by removing the three securing bolts. Start the engine and rev several times while momentarily creating exhaust system back pressure by blocking the end of the exhaust pipe with a rag. After cleaning the carbon from the exhaust pipe, reinstall the clean-out port lid. Remove the carbon from the diffuser pipe and reinstall. (1) DIFFUSERPIPE (2) SECURING BOLT (3) CLEAN-OUT PORT LID O""*! Date of Issue : Sep. 1978 (W HONDA MOTOR m 1 TO n n Z50R r r r r I' r r MEMO Date of Issue : Sep. 1978 FUEL SYSTEM Z50R Turn the fuel valve OFF. Drain fuel from the carburetor by loosening the drain screw. RUBBER CAP NOTE Before installation, check for 1 deterioration. AIR CLEANER Fuel Line Check for deterioration, cracking or other faults. Replace if necessary. THROTTLE STOP SCREW DRAIN SCREW Clean carburetor jets and body with non-flammable or high flash point solvent before installation. d-0 Date of Issue • Sep. 1978 rrs HONn/i motor rn t m f\i«jy# SP^TOOV- 7240A ^oooo r^ r Enal«e >*•*.,-correct 6 M .La'"'8*,, 6, ?St*-"- ,'H(W,e Rich mi 2 F^tftoo stuck <*<**> 3 4 Carburetor c\099ed FUEL SYSTEM HONDA. Z50R CARBURETOR ASSEMBLY/ DISASSEMBLY REMOVAL Turn the fuel valve OFF and disconnect the fuel line from the carburetor. Unscrew the two carburetor mounting bolts to remove the carburetor. Loosen the air cleaner tube connecting clamp and separate the carburetor from the air cleaner assembly. Remove the cap and disconnect the throttle cable from the carburetor. FLOAL LEVEL CARBURETOR MOUNTING BOLT THROTTLE VALVE LAMP Remove the float chamber by loosening the two screws. NOTE | Drain fuel by loosening the drain cock j before performing this maintenance. FLOAT CHAMBER Measure the float level with the float level gauge FLOAT LEVEL: 12.7 mm(0.50 in) Replace the float if the service limit is exceeded FLOAT LEVEL GAUGE: 72401-0010000 A-O Date of Issue : Sep. 1978 /», UriMHfl MOTOR <~^ HONDA. Z50R 5 ENGINE REMOVAL & . INSTALLATION i--------:------------------------------------------------- | SERVICE INFORMATION 5-1 ENGINE REMOVAL 5-2 ENGINE INSTALLATION 5-3 SERVICE INFORMATION GENERAL INFORMATION The engine must be removed to service the following parts: Crankshaft Crankweights Kick starter Connecting rod Transmission SPECIFICATION Engine weight 17 kg (37.5 lb), dry TORQUE VALUES Engine hanger 8 mm flange bolt 2.0-2.5 kg-m (15-18 ft-lb) Date of Issue : Sep. 1978 C ^ ENGINE REMOVAL & INSTALLATION ENGINE REMOVAL Dram the engine oil. Remove the exhaust pipe nuts and hanger bolts Loosen the muffler assembly. Remove the intake manifold bolts and manifold. Disconnect the spark plug cap and A. C. generator wires. Remove the gearshift pedal. Remove the left crankcase cover mounting screws and remove the cover. Unfasten the drive chain master link and remove the chain. Remove the two engine hanger bolts and remove the engine from the frame. mm 5-9 Oats of Issue : Sep. 1978 © HONDA MOTOR CO . LTD Z50R ENGINE REMOVAL & INSTALLATION ENGINE INSTALLATION The installation sequence is essentially the reverse of removal. NOTE When installing the drive chain master link, make sure that the open end of the clip faces opposite the direction of normal chain rotation. Direction of Rotation Date of Issue : Sep. 1978 :M^feMMM^ 5-3 CYLINDER HEAD/CAMSHAFT Z50R 6mm BOLT Loosen this bolt slightly and lightly tap on its head to facilitate removal of the left side cover. COPPER WASHER VALVE COVER NOTE Before installing, apply grease to the theads. COPPER WASHER LEFTSIDE COVER 6-0 Date of Issue : Sep. 1978 (P) HONDA MOTOR CO , LTD n Z50R 6 CYUNDER HEAD, CAMSHAFT r SERVICE INFORMATION TROUBLESHOOTING ROCKER ARM & ROCKER ARM SHAFT REMOVAL CAMSHAFT REMOVAL VALVE DISASSEMBLY TENSIONER PUSH ROD 6-1 6-1 6-2 6-2 6-3 6-4 r r. L SERVICE INFORMATION SPECIAL TOOLS Valve Guide Remover/Installer Valve Guide Reamer (IN/EX) Valve Spring Compressor Valve Guide Driver 07942-3290100 07984-0980000 07757-0010000 07942-3290200 r t n SPECIFICATIONS r r r r STANDARD SERVICE LIMIT Camshaft lobe height 26.07 mm (1.026 in) 25.59 mm (1.011 in) : Cylinder head warpage 0.05 mm (0.002 in) Valve seat width 1.0-1.3 mm (0.04-0.05 in) 2.0 mm (0.08 in) Valve stem 0. D. IN 5.455-5.465 mm (0.2148-0.2152 in) 5.40 mm (0.213 in) EX 5.430-5.445 mm (0.2138-0.2144 in) 5.40 mm (0.213 m) Valve guide I. D. IN/EX 5.475-5.485 mm (0.2165-0.2159 in) 5.50 mm (0.217 in) Valve spring Free length Inner 22.7 mm (0.89 in) 23.9 mm (0.94 in) Outer 24.9 mm (0.98 in) 26.9 mm (1.06 in) Valve clearance IN/EX 0.05 mm (0.002 in) TROUBLESHOOTING Engine top-end problems can usually be diagnosed by a compression test. Noise problems can usually be traced to the top-end of an engine with a sounding rod or stethoscope. Low compression or uneven compression 1 Valves — Incorrect valve adjustment — Burned or bent valve — Incorrect valve timing — Broken valve spring 2 Cylinder head — Leaking or damaged head gasket — Warped or cracked cylinder head 3 Cylinder and piston (Refer to Section 7) Compression too high 1 Excessive carbon build-up on piston or combustion chamber Excessive noise 1 Incorrect valve adjustment 2 Sticking valve or broken valve spring 3 Damaged or worn rocker arm or cam 4 Loose or worn cam chain 5 Worn or damaged cam chain tensioner 6 Loose balancer chain 7 Worn cam sprocket teeth Cam chain noise 1 Excessive free play 2 Guide roller worn Date of Issue : Sep. 1978 R-1 CYLINDER HEAD/CAMSHAFT Z50R ROCKER ARM AND ROCKER" ARM SHAFT REMOVAL Remove the rocker arm shaft by screwing in an 8 mm bolt and pulling out. CAMSHAFT REMOVAL Remove the camshaft by aligning the cam lobes with the cutouts in the cylinder head. ROCKER ARM SHAFT Install the rocker arm shaft with its threaded end facing the right side. 8 mm BOLT -CUTOUTS IN HEAD LOBES CAMSHAFT VALVE TIMING Align the "J" mark on the flywheel with the index mark. Align the camshaft sprocket index mark with the cutout in the cylinder head. INDEX MARH «_o Date of Issue : Sep. 1978 f r r Z50R CYLINDER HEAD/CAMSHAFT r r~ r n r r r VALVE DISASSEMBLY TOOL VALVE SPRING COMPRESSOR 07757-0010000 CA UTION To prevent loss of tension, do not compress the valve spring more than neces-I sary to remove or to install the valve cotters. Remove the valve and inspect the face. If the seat is too wide, too narrow, or has low spots, the seat must be ground. NOTE After installing, check that these cotters are seated pro- perly. NOTE____________________ I Valve stem seal and cap are i used only on the exhaust side NOTE Follow the valve refacer manufacturer's operating instructions. PILOT BAR"A" 07783-0010100 -safe ,VALVE SRPING SEAT fj - VALVE STEM SEAL CAP A® 'VALVE STEM SEAL INTAKE VALVE VALVE SPRINGS VALVE GUIDE O-RING EXHAUST VALVE GRIDING STONE I N : 07783-0050100 EX : 07783-0050100 I N : 07783-0030200 EX : 07783-0030100 I N : 07783-0040200 EX : 07783-0040100 A 63 5° \ / \ /A 37.5 \ / /w \ / Date of Issue : Sep. 1978 a HONDA MOTOR CO LTD o-o CYLINDER HEAD/CAMSHAFT Z50R TENSIONER PUSH ROD Install the push rod with .the taper facing bolt "A". TENSIONER ADJUSTING BOLT B The end of adjusting bolt "B" must not contact this surface. ADJUSTING BOLT "B" CRANKCASE CAP BOLT 6-4 Data of Issue : Sep. 1978 (?) HONDA MOTOR CO LTD r r Z50R MEMO r r r r r t t r r Date of Issue • Sep 1978 •c^fe«4*^:; CYLINDER/PISTON Z50R 8x 14 mm DOWEL PIN CYLINDER PISTON PIN CIRCLIP CHAIN GUIDE ROLLER 6mm BOLT TORQUE: 0.9-1.2 kg-m (7-9 ft-lb) NOTE Tighten this screw loosenly during cylinder assembly. Tighten to the specified torque after tightening the cylinder head. 16mmO-RING 7-0 Date of Issue : Sep. 1978 RHONDA MOTOR CO ITO r r. P r~ I: r~ r r Z50R 7 CYLINDER PISTON SERVICE INFORMATION TROUBLESHOOTING PISTON REMOVAL 7-1 PISTON RING REMOVAL 7-2 7-1 PISTON RING INSTALLATION 7-2 7-2 CYLINDER INSTALLATION 7-3 CAM CHAIN GUIDE ASSEMBLY 7-3 r. r i. r r. SERVICE INFORMATION SPECIFICATIONS STANDARD SERVICE LIMIT Cylinder |_ d. 39.005-39.015 mm (1.5356-1.5360 in) 39.05 mm (1.537 in) Piston O.D. at skirt 39.980-39.000 mm (1.5346-1.5354 in) 38.90 mm (1.532 in) Piston pin bore 13.002-13.008 mm (0.5119-0.5121 in) 13.10 mm (0.516 in) Piston ring Width Top 1.70-1.90 mm (0.067-0.075 in) 1.60 mm (0.063 in) Second 1.70-1.90 mm (0.067-0.075 in) 1.60 mm (0.063 in) Piston ring End gap Top 0.10-0.30 mm (0.004-0.012 in) 0.50 mm (0.020 in) , Second 0.10-0.30 mm (0.004-0.012 in) 0.50 mm (0.020 in) Piston ring-to-groove clearance Top 0.010-0.045 mm (0.0004-0.0018 in) 0.12 mm (0.005 in) Second 0.010-0.045 mm (0.0004-0.0018 in) 0.12 mm (0.005 in) Piston pin 0. D. 12.994-13.000 mm (0.5116-0.5118 in) 12.98 mm (0.511 in) ! TROUBLESHOOTING Compression too low or unstable 1 Worn cylinder or piston Excessive smoke 1 Worn cylinder or piston 2 Improper installatio of piston rings 3 Scored or-scratched piston or cylinder wal Overheating 1 Excessive carbon build-up on piston or combustion chamber wall Knocking or abnormal noise 1 Worn piston and cylinder 2 Excessive carbon build-up r Date of Issue : Sep. 1978 7-1 CYLINDER/PISTON Z50R PISTON REMOVAL NOTE Install the circlip so that its end gap and the cutout are not aligned. Install the piston with the marking "V" facing the exhaust side. PISTON RING REMOVAL PISTON RING INSTALLATION Clean the ring grooves and oil holes throughly. NOTE After installation, the rings should be free to rotate in the ring grooves. NOTE j Do not interchange rings. Space the ring end gaps 120° apart, avoiding the piston pin and thrust sides. PISTON PIN CIRCLIP Remove the piston rings by lifting in the direction shown. <\ -id)TOP RING ~p) SECOND RING -p) OIL RING nstall the rings with the markings facing up. T-O Date of Issue : Sep. 1978 [": HONDA. Z50R CYLINDER/PISTON r n r r r I; r r r CYLINDER INSTALLATION Apply a thin coating of oil to the piston rings and cylinder wall, and compress the piston rings so they will enter the cylinder. NOTE When the cylinder is halway over the piston, route the cam chain through the hole in the cylinder. NOTE Do not allow the 16 mm O-ring to become mispositioned. CAM CHAIN GUIDE ASSEMBLY Tighten the guide roller pin after installing the guide. 8x 12mm_DOWELPINS ,6nm0-UNG' gpa CYLINDER GASKET 8 x 14 mm DOWEL PIN 7.5 mm RUBBER PACKING CAM CHAIN GUIDE 16mmO-LING GUIDE ROLLER PIN r r r r~ Date of Issue : Sep. 1978 7-3 CLUTCH/GEARSHIFT SPINDLE Z50R PIVOT BOLT DRUM STOPPER PLATE DRUM STOPPER RIGHT CRANKCASE 17mm SNAP RING RIGHT CRANKCASE COVER CLUTCH OUTER COVER CLUTCH CAM CLUTCH BALL RETAINER CLUTCH LIFTER CLUTCH ADJUSTING BOLT ft-0 Date of Issue : Sep. 1978 Z50R 8 CLUTCH/ GEARSHIFT SPINDLE r~ L SERVICE INFORMATION TROUBLESHOOTING CLUTCH REMOVAL CLUTCH DISASSEMBLY CLUTCH INSPECTION GEARSHIFT SPINDLE ASSEMBLY 8-1 8-1 8-2 8-2 8-3 8-3 SERVICE INFORMATION GENERAL INFORMATION This section covers clutch removal and installation. Service can be accomplished with the engine in the frame. r f SPECIAL TOOLS 14mm Lock Nut Wrench Clutch Outer Holder SPECIFICATIONS 07716-0010100 07923-0400000 f- STANDARD SERVICE LIMIT i Clutch spring free length Clutch disc thickness 21.1 mm (0.83 in) 3.45 mm (0.136 in) 19.4 mm (0.76 in) j 3 15 mm (0.124 in) TROUBLESHOOTING Faulty clutch operation can usually be corrected by proper adjustment. Clutch slips when accelerating 1 No free play 2 Discs worn 3 Springs weak Clutch will not disengage 1 Plate warped Clutch drags when disengaged 1 Lifter mechanism damaged Date of Issue : Sep. 1978 /=- HOMO ft MOTOR CO I TO 8-1 CLUTCH/GEARSHIFT SPINDLE HONDA Z50R CLUTCH REMOVAL TOOLS: CLUTCH OUTER HOLDER 07923-0400000 14mm LOCK NUT WRENCH 07716-0010100 Straighten the lock washer tab holding the nut. NOTE i Do not re-use the lock washer when assembling. Remove the lock nut. CLUTCH DISASSEMBLY CLUTCH FRICTION DISC DISASSEMBLY/ASSEMBLY Replace the clutch discs if they show signs of scoring or discoloration. Measure the disc thickness. SERVICE LIMITS: Disc : 3.15 mm (0.124 in) CLUTCH OUTER DISASSEMBLY/ ASSEMBLY NOTE I Tighten the screws in a criss-cross I pattern in 2-3 steps. CLUTCH PLATE "A" DAMPER SPRING CLUTCH OUTER FRICTION DISCS "A" SET SPRING CLUTCH PLATE "B' CLUTCH SPRING CLUTCH CENTER DRIVE GEAR OUTER CLUTCHOUTER CLUTCH DAMPER SPRING 5mm SCREW Date of Issue : Sep. 1978 © HONDA MOTOR CO . LTD. r {-> Z50R CLUTCH/GEARSHIFT SPINDLE r~ CLUTCH INSPECTION Check the clutch spring free length. SERVICE LIMIT : 19.4 mm {0.76 in) CLUTCH PLATE A, DRIVE PLATE AND 8 x 10 mm ROLLER INSPECTION Check the rollers and plates for excessive wear. Replace if necessary. GEARSIFT SPINDLE ASSEMBLY DRUM STOPPER PLATE INSTALLATION NOTE Install the stopper plate aligning the hole with the stepped dowel. DAMPER SPRING O"»(o, CLUTCH SPRING DRIVE PLATE CLUTCH PLATE "A" DRIVE PLATE 8x10 mm ROLLER Date of Issue ¦ Seo 1978 o o CLUTCH/GEARSHIFT SPINDLE HONDA. Z50R GEARSHIFT SPINDLE INSTTALATION NOTE Do not rotate the spindle as the lip of the oil seal may be scored or scratched. DRUM STOPPER INSTALLATION Install the drum stopper loosely. Position the stopper onto the drum as shown. Tighten the stopper pivot bolt securely. DRUM STOPPER PIVOT BOLT 8-4 Date of Issue : Sep. 1978 f* Hoiuna motor ro i r-' HONDA Z50R t MEMO r r~ r Date of l I___________________________J PROBABLE CAUSE -(1 -(2 -<3 -(4 -(1 -(2 (3 _(4 (5 -(6 h<7 -(8 -(9 (1 -(2 -(3 -(4 -(5 -(1 -(2 -(3 No fuel in fuel tan!. Clogged fuel line or fuel filter Clogged carburetor jets Clogged fuel tank cap breather hole Faulty spark plug Fouled spark plug Fouled contact breaker points Improper breaker point gap Faulty condenser Broken or shorted high tension cord Broken or shorted ignition coil Faulty main switch Improper ignition timing Valve clearance too small Bent valve : open Worn cylinder and piston rings Leaking cylinder head gasket Improper valve timing Misuse of choke Carburetor pilot screw excessively closed Manifold air leak A -(1) Carburetor overflooded -(2) Carburetor choke excessively closed '—(3) Throttle valve excessively open ENGINE LACKS POWER SYMPTOM 1 Tire pressure normal Tire pressure is too low Engine speed lowered when gear changed Engine speed not changed when gear changed CHECK L' Try rapid acceleration from low to second .J -I Lightly accelerate engine ( PROBABLE CAUSE ¦—(1) Punctured tire I—(2) Faulty tire valve -(1) Clutch slipping -(2) Worn clutch disc -(3) Clutch disc warped 15-2 Date of fssue : Sep. 1978 n r Z50R TROUBLESHOOTING r r r r r f; r r r Engine speed increased Engine speed not increased sufficiently JI I Check ignition timing using test lamp Ignition timing is correct 1 Improper ignition timing (1 (3 (4 (5 (1 -l Check valve clearance I I____________________________l Valve clearance is normal Valve clearance is not correct Compression is normal Compression is low Test cylinder compression by operating kick starter and using compression gauge "I (1 h(2 (3 (4 "| Check carburetor for clogg- | L(5 Carburetor is not clogged 1 mg .J Carburetor is clogged Spark plug is not fouled or or discolored 1 | Remove spark plugs -(1 ._l Spark plug is fouled or discolored ~~~\ Remove oil level gauge and | I check oil level and fouling _l Oil pressure normal T Oil level is not correct Normal oil pressure Low oil pressure .J------------------------------- | Check oil pressure I___________________ "1 I I .J L(2 -<1 L(2 (1 (2 M3 -t J_ • H Check if engine overheats .J Engine is not overheated Engine overheats L_ Accelerate or run at high speed —i Engine does not knock Engine knocks (1 (2 -(3 M4 Carburetor choke closed Dirty air cleaner Restricted fuel flow Clogged fuel tank breather cap hole Clogged muffler improper contact breaker point gap Improper valve clearance Worn valve seat Bent valve Worn cylinder and piston rings Leaking cylinder head gasket Flaws in cylinder head Improper valve timing Fuel filter not serviced frequently enough Use of low quality fuel Plugs not serviced frequently enough Use of plug with improper heat range plug Oil level too high Oil level too low Contaminated oil Clogged oil passage Poor oil pump delivery Excessive carbon build-up on combustion chamber wall Use of low quality fuel Clutch slipping Fuel-air mixture too lean Worn piston and cylinder Fuel air mixture too lean Use of low quality fuel Excessive carbon build-up in combustion chamber Ignition timing advanced r Date of Issue : Sep. 1978 15-3 TROUBLESHOOTING HONDA. Z50R • POOR PERFORMANCE AT LOW AND IDLE SPEEDS Normal Normal Not leaking Good spark SYMPTOM Q Incorrect Incorrect Leaking CHECK I Check ignition timing and i valve clearance PROBABLE CAUSE (1) Improper valve clearance (2) Improper ignition timing __} Check carburetor pilot i I screw adjustment I _ ! Air is leaking past carburet-[ or packing --| Try spark test Weak or intermittent spark ._l — (1) Fuel air mixture too lean L(2) Fuel air mixture too rich |—(1) Deteriorated insulator (2) Loose carburetor r (1) Defective, carbon or wet fouled spark plug (2) Fouled breaker points — (3) Condenser shorted (4) Low battery 15-4 Date of Issue : Sep. 1978 Z50R TROUBLESHOOTING ENGINE LACKS HIGH SPEED PERFORMANCE SYMPTOM Q CHECK Check ignition timing and valve clearance PROBABLE CAUSE 1 !____ Timing and clearance normal Timing and clearance improper (1) Improper adjustment j Check for clogging by dis- | 1 connecting fuel line at ' i carburetor . L_. .J Not clogged Clogged (1) Fuel line clogged el tank (2) Fuel tank cap breather hole clogged i---------------------------------------------------------------------1 - I Remove carburetor and | l-(4) Fuel filter dirty I inspect jets I I__________________________J Fuel flows out freely Fuel flow restricted (1) Clean r- —I Replace carburetor jets I Condition aggravated Condition improved I (1) Main jet size too small "(2) If improved with smaller size -| Jet: --] Check valve timing | a\ Air cleaner clo99ed . i b) Choke valve not opening ------------------------------------------- fully Timing normal Engine out of time I----------------------------------------- I -J Test valve spring tension (1) Cam sprocket aligning marks not aligned Tension normal Weak or broken spring (1) Faulty valve spring A Date of Issue : Sep. 1978 15-5 TROUBLESHOOTING Z50R SMOKY EXHAUST SYMPTOM O Smoke disappeared Smoky exhaust CHECK --I Try high speed running i j--------------------------------, i i —\ Close throttle grip quickly I I I I_________________________________________________I PROBABLE CAUSE (1) Worn cylinder and piston rings (2) Crankcase oil level too high (3) Piston rings installed upside down — (4) Scored or scuffed piston or cylinder wall '— (5) Flaws in cylinder head : No white exhaust White smoke emitted immediately after closing grip ____ L_ Try low speed running j— (1) Worn intake valve guide or stem t— (2) Valve guide O-ring not seated properly No smoke 1 White smoke (1) Worn exhaust valve stem and guide — (2) Exhaust valve guide improperly pressed in '—(3) Worn exhaust valve stem seal • FAULTY CLUTCH OPERATION SYMPTOM O n Adjust clutch properly j I__________________________J Clutch slipping PROBABLE CAUSE ~ (1) Weak clutch spring —(2) Worn or warped clutch plate — (3) Worn or warped clutch disc Clutch drags j— (1) Plates or discs warped "*— (2) Uneven clutch spring tension Date of Issue : Sep. 1978 n r Z50R TROUBLESHOOTING • FAULTY TRANSMISSION OPERATION o SYMPTOM -(Clutch operates properly) PROBABLE CAUSE r Hard to shift into gear - (1) Gearshift arm spring broken — (2) Shift forks bent -(3) Shift drum and shift fork binding ~<4) Gear dogs broken or worn excessively — (5) Shift arm pawl out of engagement with shift drum pin — (6) Drum stopper plate and drum stopper improperly set n r n A Gearshift pedal does not return Transmission jumps out of gear I— (1) Gearshift return spring broken -(2) Gearshift spindle interfering with crankcase or left cover -(1) Shift guide fork pin worn (2) Shift forks bent or worn -(3) Shift drum stopper spring broken or weak r l: r r •ENGINE NOISE Q SYMPTOM Valve noise Piston slap Cam chain noise -> Clutch noise A Drive and driven gear noise ¦c PROBABLE CAUSE (1) Excessive valve clearance (2) Worn valve (1) Cylinder or piston worn ¦ (2) Carbon deposits in combustion chamber • ¦ (3) Worn piston pin or connecting rod small end I— (1) Worn camshaft (2) Worn camshaft sprocket teeth (3) Excessive chain slack C(1) Excessive clearance between clutch plate and clutch outer teeth (2) Weak clutch damper spring -c (1) Worn or deteriorated driven gear damper (2) Worn drive and .driven gears Date of Issus .Sep. 1978 15-7 TROUBLESHOOTING Z50R STEERS TO ONE SIDE OR DOES NOT TRACK STRAIGHT o SYMPTOM PROBABLE CAUSE -(Both tire pressures normal) Steering heavy -r— (1) Steering cone races excessively tightened '— (2) Damaged steering race Front or rear wheel wobbles excessively - (1) Excessive wheel bearing play (2) Distorted rim — (3) Improperly installed wheel hub -(4) Swing arm pivot bushing excessively worn -(5) Bent frame -(6) Improper drive chain tension or adjustment Pulls to one side — (1) Shock absorbers unevenly adjusted — (2) Front and rear wheels not aligned — (3) Bent front fork — (4) Bent swing arm • IMPROPER FRONT/REAR SUSPENSION o SYMPTOM PROBABLE CAUSE -----(Tire pressure normal) Soft suspension -(1) Weak spring -(2) Excessive load -(3) Incorrect weight oil in front forks Hard suspension -r— (1) Faulty shock absorber damper valve '—(2) Front forks assembled incorrectly Excessive or abnormal noise j— (1) Damaged damper "I—(2) Front fork assembled incorrectly 15-8 Date of issue : Sep. 1978 © HONDA MOTOR CO LTD Z50R 16.W81 ADDENDUM SPECIFICATIONS SPARK ARRSTER CABLE AND WIRE HARNESS ROUTING MAINTENANCE SCHEDULE FUEL SYSTEM A.C. GENERATOR WHEEL AND BRAKE HANDLEBAR WIRING DIAGRAM 16-2 16-4 16-5 16-6 16-7 16-8 16-9 16-11 16-12 INTRODUCTION This Honda Shop Manual Addendum contains information for the '80 and '81 Z50R. Refer to the base Shop Manual for service procedures and data not included in this addendum. ALL INFORMATION AND ILLUSTRATIONS 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 Date of Issue Sep , 1980 1«-1 '80-'81 ADDENDUM HONDA Z50R SPECIFICATIONS I I Item Metric English Dimensions Overall length 1,300 mm 51.2 in Overall width 605 mm 23.8 in Overall height 810mm 31.9 in i Wheel base 895 mm 35.2 in ! Seat height 575 mm 22.6 in i Foot peg height 220 mm 8.7 in Ground clearance 140 mm 5.5 in j Dry weight 49.5 kg 109.1 lb ; Frame Type Backbone • Front suspension Telescopic fork I Rear suspension Swing arm Front tire size 3.50-8-2PR I Rear tire size 3.50-8-2PR I Cold tire pressures Front 1.0 kg/cm2 14 psi Rear 1.0 kg/cm2 14 psi Front brake Internal expanding shoe Rear brake Internal expanding shoe Fuel capacity 5.0 lit 1.3 US gal Fuel reserve capacity 0.7 lit 0.18 US gal. Caster (Degrees from horizon tal) 25° Trail 42 mm 1.7 in Front fork oil Grease Engine Type Air-cooled, 4 stroke OHC ' Cylinder arrangement Single 80* inclined from vertical Bore and stroke 39.0x41.4 mm 1.535 x 1.630 in 1 Displacement 49 cm2 3.0 cu in Compression ratio 8.8 Valve train Chain driven overhead camshaft Oil capacity 0.8 lit 0.85 US qt Lubrication system Forced and wet sump Cylinder head compression p ressure 12.0 kg/cm2 - -1,000 rpm 168 psi ! Intake valve Opens 7° BTDCfat 1mm lift) Closes 12° ABDC(at 1mm lift) Exhaust valve Opens 22° BBDCfat 1mm lift) Closes 2° ATDCfat 1mm lift) Valve clearance (cold) IN 0.05 mm 0.002 in EX 0.05 mm 0.002 in Idle speed 1500+ 100 rpm Engine dry weight 17 kg 37.5 lb ilS-O Date of Issue- Sep., 1980 /0\ HONDA ^KL) Z50R ;t'80-'81 ADDENDUM I Item Metric English Carburetion Carburetor type Piston valve Venturi diameter , 11 mm 0.43 in 1 Identification number PA03C , Air screw opening 1-1/2 , Float level 12.7±1 mm I 0.50±0.04 m i Drive train Clutch Wet multi-plate automatic (centrifugal) I Transmission 3-speed constant mesh i ! Primary reduction ratio 3.722 | 1 Gear ratio 1 3.181 Gearratio II 1.823 \ Gear ratio III 1.190 ! 1 Final reduction ratio 3.083(37/12) | 1 Gear shift pattern Left foot operated return system N—1-2—3 ! Electrical Ignition A.C. magneto \ Generator Flywheel : ; Starting system i Kick start I ., - Spark plug U.S.A. type NGKC6H ND U20FS J ; Canada type NGKCR6HS NDU20FSR-L ! Spark plug gap 0.6-0.7 mm 0.024-0.028 in s D»tp nf kwii' Son 1PB0 4G -O '80-'81 ADDENDUM Z50R SPARK ARRESTER Remove the right number plate. Remove the tj'xC''IM spark arrester from the exhaust pipe. Ifatil Remove the clean out cap. Start the engine and rev it about ten times while blocking the exhaust pipe with a shop towel. Reinstall the clean out cap. Clean the spark arrester and reinstall it and the number plate. WARNING Do not perform this operation immediately after the engine has been run because the exhaust system becomes very hot. Because of the increased fire hazard ensure that there are no combustible materials in the area when purging the spark arrester. Wear eye protection Never run the engine in a closed area. The exhaust contains poisonous carbon monoxide gas. 1^ - A. Date of Issue: Sep., 1980 Z50R 80—'81 ADDENDUM CABLE AND WIRE HARNESS ROUTING ENGINE STOP SWITCH WIRE THROTTLE CABLE IGNITION COIL PRIMARY LEAD Date of Issue Sep , 1980 1R-5 '80-'81 ADDENDUM Z50R MAINTENANCE SCHEDULE The maintenance intervals shown in the following schedule are based upon average riding conditions. Machines subjected to severe use, or ridden in unusually dusty areas, require more frequent servicing. Items marked *should be serviced by an authorized Honda dealer, unless the owner has proper tools and is mechanically qualified. WARMNG To prevent personal injury, always make certain the engine is stopped and the motorcycle is supported securely on a level surface prior to performing any maintenance. ¦ I Inspect and Clean, Adjust, Lubricate or Replace if necessary C Clean R- Replace A' Adjust L: Lubricate NOTE (1) Replace every 30 operating days or whichever comes first. (2) Service more frequently when riding every 3 months, in dusty areas. INITIAL SERVICE PERIOD (First week of operation.) REGULAR SERVICE PERIOD (Every 30 operating days.) ENGINE OIL NOTE (1) (2) R R • CONTACT BREAKER POINTS I I * IGNITION TIMING I I ? VALVE CLEARANCE I I SPARK PLUG I * CARBURETOR I I AIR CLEANER ELEMENT NOTE (2) C THROTTLE OPERATION I I FUEL LINE I (EVERY YEAR) * FUEL FILTER SCREEN C: (EVERY YEAR) DRIVE CHAIN I I ' • CLUTCH I I , SPARK ARRESTER C BRAKE CONTROL LINKAGE I I ' • BRAKE SHOES 1: (EVERY YEAR) * STEERING HEAD BEARING A: (EVERY YEAR) 1 i ' TIRES I 1 ! ALL NUTS, BOLTS, FASTENERS I 1 IC.ft Data of Issue: Sep., 1980 r r Z50R '80-'81 ADDENDUM FUEL SYSTEM CARBURETOR SPECIFICATIONS r i. r r r WARNING Gasoline is extremely flammable and is explosive under certain conditions. Do not smoke or allow flames or sparks in your working area. DISASSEMBLY AND ASSEMBLY For details, refer to the base Z50R Shop Manual. NOTE I Standard setting Identification No. PA03C Main jet #58 Jet needle setting 2nd (from top) Air screw opening 1-1/2 turns out Float level 12.7 ±1 mm Idle speed 1,500 rpm When disassembling fuel system parts, note the location of the O-rings. The float chamber has a dram plug that can be loosened to drain residual gasoline. , .RUBBER CAP NOTE Before installation, check for deterioration. AIR CLEANER JfiVv.i>"-^ Fuel Line Check for deterioration, cracking or other faults. Replace if necessary. O-RING NOTE Replace used O-rings. THROTTLE STOP SCREW Date of Issue Sep , 1980 16-7 '80-'81 ADDENDUM Z50R A.C. GENERATOR WOODRUFF KEY STATOR FLYWHEEL LEFT CRANKCASE COVER 1R-R Date of Issue: Sep., 1980 Z50R '80—'81 ADDENDUM WHEEL/BRAKE SPECIFICATIONS Item STANDARD SERVICE LIMIT Brake lining thickness (front/rear) 3.5 mm (0.4 in) 2.0 mm (0.08 in) Brake drum I.D (front/rear) 80.0 mm (3.15 in) 81.0 mm (3 19 in) Front and rear axle nut torque ('81 model): 4.5— 5.5kg-m(33-40ft-1b) FRONT WHEEL CAUTION ~! WHEEL RIM Deflate tires before disassembling the wheel, WHEEL HUB CZ^3) \ DISTANCE COLLAR BEARING NOTE The bearing sealed end faces out DUST SEAL cmjW SIDE COLLAR EARING REAR WHEEL WHEEL RIM TIRE BEARING NOTE The bearing sealed end faces out. DRIVEN SPROCKET '80-'81 ADDENDUM Z50R BRAKE LINING INSPECTION Remove the wheel. Remove the brake panel from the wheel hub. Measure the brake lining thickness. SERVICE LIMIT. 2.0 mm (0.08 in) Replace the brake shoes if necessary. WARSING Keep grease off the inside of the wheel hub I and brake lining surfaces. BRAKE SHOE REPLACEMENT Remove the shoe spring from the anchor pin. Remove the brake shoes from the brake panel. Remove the brake arm. Remove the brake cam and indicator tab. Apply grease to the brake cam and brake shoe anchor pin. BRAKE PANEL ASSEMBLY Assemble the brake shoes in the reverse order of removal ANCHOR PIN BRAKE SHOE SPR BRAKE ARM DUST SEAL BRAKE PANEL BRAKE SHOE BRAKE ARM NOTE BRAKE SHOE SPRING Align the punch mark on the arm with the punch mark on the camshaft Align the indicator tab b'raKE CAM with the cut out in the brake camshaft. •4 a -i t\ Date of Issue: Sep., 1980 Z50R 80—'81 ADDENDUM BRAKE DKUM I.D. Clean the inside of brake drum using a clean cloth. Mesure the brake drum I.D. FRONT and REAR SERVICE LIMIT: 81.0 mm (3.19 in) HANDLEBAR THROTTLE GRIP ENGINE STOP SWITCH WIRE THROTTLE CABLE 3.0-4.5 kg-m (22-33 ft-lb) FRONT BRAKE CABLE WIRE BAND HANDLEBAR Date of Issue: Sep., 1980 ^ ! trvMr> i\ MOTnp no 1 TO 16-11 '80-'81 ADDENDUM HONDA Z50R WIRING DIAGRAM ENGINE STOP SWITCH ENGINE STOP SWITCH CONTINUITY IG OFF o- RUN OFF O Color Black/White -o ¦o Green Black/White - A.C. GENERATOR F Black/White Black/White 777777 16-12 Date of Issue: Sep., 1980 © HONDA MOTOR CO \ TO r r r I r Z50R 17.'82 ADDENDUM INTRODUCTION This addendum contains only new information for the 1982 Z50R. Refer to the base shop manual for service procedures and data not included here. ALL INFORMATION AND ILLUSTRATIONS 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 CONTENTS I. SPECIFICATIONS..................17-2 II. LUBRICATION....................17-2 III. FUEL SYSTEM.....................17-3 IV. CYLINDER HEAD/VALVES..........17-5 Date of Issue: September, 1981 17-1 /^5\ HOItfDA. '82 ADDENDUM \JK/ Z^0R 1. SPECIFICATIONS ITEM ENGINE Compression ratio 95.1 CARBURETION Carb identification no. PA03D DRIVE CHAIN Final reduction ratio 2.846(37/13) ELECTRICAL Spark plug NGKCR6HS ND U20FSR-U II. LUBRICATION SPECIFICATIONS Use HONDA 4-STROKE OIL or equivalent. API SERVICE CLASSIFICATION SE or SF VISCOSITY SAE10W-40 Other viscosities shown in the chart may be used when the average temperature in your riding area is within the indicated range 20 0 20 40 60 80 100° F I________I________I________I________i________I________I________i 30 -20 -10 0 10 20 30 40° c OIL PUMP ASSEMBLY Align the flat on the shaft with the flat on the inner rotor After assembling, check that the shaft rotates freely without binding INSTALLATION With the gasket in place, install the oil pump by aligning the rotor shaft groove with the tang on the cam chain guide spindle SAE20W-40. 20W-50 T SAEtOW-40 SAE10W-30 17-9 Date of Issue September, 1981