Page 2
The intention is to provide as much assistance as possible to mechanics working in our brand’s dealers and sub-dealers. Due to its constant commitment to improving its products, DERBI - NACIONAL MOTOR, S.A.U. reserves the right to introduce any modifications it deems fit, without prior warning.
INDEX I N D EX I N D EX ND E X GENERAL INFORMATION Pág. 4 CARACTERISTICS Pág. 5-6 TIGHTENING TORQUES Pág. 7 M AINTENANCE Pág. 10 MAINETANCE CHART Pág. 10-11 ENGINE OIL Pág. 11 DISTRIBUTION Pág. 13 DISTRIBUTION - COMPRESSION MOTOR Pág.
GENERAL INFORMATION G E N ER AL IN F O R M AT I O N ULES ULES This section describes the general safety rules and service recommendations to be observed. AFETY RULES AFETY RULES - Should it be necessary to run the engine in order to perform certain operations, please ensure the area is adequately ventilated and, if required, use appropriate fume extractors;...
CHARACTERISTICS C H A R AC T ER I S TI C S CHASSIS CODE ENGINE CODE DIRTBOY 10 ZEMMR4CC24 ¿AXXXXXX? C391M ¿XXXX? DIRTKID 12 ZEMMS4CC64 ¿AXXXXXX? C391M ¿XXXX? ARACTERISTICS ARACTERISTICS CHASSIS, Frame Steel WHEELS AND Fork Steel BRAKES Inner tube 2,5 x 10”...
Page 6
CHARACTERISTICS C H AR AC T ER I S TI C S ECHNICAL DATA ECHNICAL DATA SPECIFICATION DESC. / QUANTITY Engine Four-stroke mono-cyl-inder Bore per stroke 39 x 41,8 mm. Displacement 49,93 mm. Compression ratio 11,5 ÷12,5:1 Carburettor Dell’orto PHVA Recommended spark plug Champion RG 4 HC overhead single camshaft, two valves, chain controlled on l.h.
TIGHTENING TORQUES T I G H T E N IN G TO R QU E S NGINE ASSEMBLY NGINE ASSEMBLY TORQUE IN Nm NAME Spark plug: 10 ÷ 15 Nm Head cover screw 8 ÷ 10 Nm 6 ÷ 7 + 135º+90º Nm for first fitting, Head-cylinder stud nut 6 ÷...
MAINTENANCE M AI N T ENA N C E AINTENANCE CHART AINTENANCE CHART FREQUENCY ACTION Engine Oil - Level Check/Top up Every 3 month Spark plug/electrode gap - Check Every 3 month Every 3 month Air Filter - Cleaning Every 3 month Idle speed / Fuel - Adjust Every 6 month Acceleration command - Adjustment...
Page 9
MAINTENANCE M A I N T E NA N C E AINTENANCE CHART AINTENANCE CHART ACTION FREQUENCY At 80 hours or 24 month Engine oil - Replacement Idle speed / Fuel - Change At 80 hours or 24 month Filtro aceite - Sustitución At 80 hours or 24 month Valve clearance - Check At 80 hours or 24 month...
MAINTENANCE M A I N T E N AN C E LECTRICAL CHARACTERISTICS Distance between electrodes 0.8 ÷ 0.9 mm AGNETIC FLYWHEEL RESISTANCE AGNETIC FLYWHEEL RESISTANCE EARTH YELLOW Infinite 55 ± 10% EARTH Infinite BROWN EARTH BLACK 100 ± 10% EARTH 100 ±...
Page 11
MAINTENANCE M A I N T E NA N CE Fill up the engine with the recommended oil, using the filler hole on the RHS engine cover. Tighten the cap manually. N.B. LET THE ENGINE RUN FOR A FEW MINUTES, THEN CHECK THE OIL LEVEL AGAIN, WITH THE ENGINE COLD;...
Page 12
MAINTENANCE MA I N T E N AN C E Ensure the reference mark on the camshaft control ring is aligned with that machined on the head, as shown in the second figure. If the marking is on the side opposite to the reference on the head, perform a complete revolution of the crankshaft, since the piston must be at the TDC of the ignition phase.
Page 13
MAINTENANCE M AI N T E NA N C E HECKING THE END COMPRESSION PRESSURE SS O - With the engine cold, remove the spark plug cap. - Remove the spark plug. - Using a 10mm adapter, install a compression test manometer on the spark plug housing, and tighten at the prescribed torque.
Page 14
ENGINE E N G I N E UTOMATIC TRANSMISSION RANSMISSION COVER - Remove the seven cover fixing screws. - Remove the screw and the kick-start. - Remove the seeger ring and the washer shown in the figure. - Remove the sector gear. ICKSTART ICKSTART - Search for excessive wear in the toothed segment, the toothed...
Page 15
ENGINE E N G I N E - Check the thickness of the friction material of the masses. If the friction material of the mass is found to be missing the circumferential grooves or cleats, the clutch is to be considered excessively worn and the masses should therefore be replaced.
ENGINE E N G I N E EFITTING THE CLUTCH EFITTING THE CLUTCH - Before refitting the assembly, carefully grease the roller bearing inside the gear housing. - Refit the clutch assembly, the drum washer, and the nut using the special tool. -After refitting, ensure the drum spins freely.
Page 17
ENGINE E N G I N E EMOVING THE STATOR EMOVING THE STATOR - Remove the two stator fixing screws as shown in the figure. EFITTING THE FLYWHEEL COVER EFITTING THE FLYWHEEL COVER According to the versions (kick-start/electric). Locking torques (N*m) Flywheel cover fixing screw: 2,5 - 3 Nm LYWHEEL AND STARTING - Restrain the rotation of the flywheel using the special tool.
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E NG I N E - CY LINDE R AS SY. A N D T IMIN G SYST E M EMOVING THE ROCKER EMOVING THE ROCKER ARMS COVER ARMS COVER Remove the four tappet cover fastenings; remove the cover complete with the 0-ring.
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E N G I N E - CY LINDE R A SS Y. A N D TI MIN G SYST EM - Remove the tappet cover. - Remove the central screw and the belleville washer shown in the figure using the specific tool to lock camshaft ring gear.
Page 20
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E N G I N E - CY LINDE R A SS Y. AN D T IMIN G S YST E M Specific tooling 020450Y Camshaft fitting/removing tool 004499Y Bearing extractor Remove the rocker arm pivot through the hole on the flywhe- el side and simultaneously remove the rocker arms.
Page 21
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E N G I N E - CY LINDE R A SS Y. A N D TI MIN G SYST EM EMOVING THE VALVES EMOVING THE VALVES Using the specific tool with the part shown in the figure, re- move the cotter halves, the caps and the springs from both valves.
Page 22
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM EN G I N E - CY LINDE R A SS Y. AN D T IMIN G S YST E M NSPECTING THE SMALL END Using an inside micrometer, measure the small end diame- ter.
Page 23
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E N G I N E - CY LINDE R AS SY. A ND TIMIN G SYSTE M - Measure the piston outside diameter perpendicularly to the piston pin axis. - Take the measurement 27 mm from the piston top as shown in the figure.
Page 24
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM EN G I N E - CY LINDE R A SS Y. AN D T IMIN G S YST E M - Measure the piston protrusion compared to the head plane and use the chart below, to determine the proper base gas- ket thickness.
Page 25
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E N G I N E - CY LINDE R AS SY. A ND TIMIN G SYSTE M TANDARD MATING PLAY NAME DIMENSIONS INITIALS QUANTITY 0,030 ÷ 0,065 mm 1º Ring 0,020 ÷ 0,055 mm 2º...
Page 26
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E NG I N E - CYLI ND ER A S SY. A N D T IMIN G SYST E M N.B. BEFORE REPLACING THE PISTON RINGS ONLY, ENSURE THAT THE CLEARANCE BETWEEN THE PISTON RINGS AND THE PISTON RING GROOVES, AND BETWEEN THE PISTON AND THE CYLINDER, IS AS SPECIFIED.
Page 27
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E N G I N E - CY LIND ER A SS Y. A N D T IMING SYST EM EMOVING THE PISTON EMOVING THE PISTON - Fit the piston and the piston pin to the connecting rod. The arrow on the piston must face the exhaust side.
Page 28
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E N G I N E - CY LINDE R A SS Y. A N D T IMING SYST EM EFITTING THE PISTON RINGS EFITTING THE PISTON RINGS - Fit the scraper starting with the spring. Ensure that the scra- per ends do not overlap.
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E N G I N E - CY LI NDER ASS Y. AN D T IMIN G SYS TE M N.B. SEE “REFITTING THE TIMING CHAIN”, TO BE CARRIED OUT BEFORE RECOUPLING THE HALFCRANKCASES. - Insert the spacer on the camshaft.
Page 30
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E N G I N E - CY LIND ER A SS Y. A N D T IMI NG SYST EM TANDARD DIAMETER SPECIFICATIONS DESC. / QUANTITY Ø 32,015 ÷ 32,025 mm Standrad diameter A: Ø...
Page 31
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E NG I N E - CY LI NDER A S SY. A N D TIMIN G SYSTE M NSPECTING THE VALVE SEALINGS NSPECTING THE VALVE SEALINGS Measure the width of the sealing surface on the valve seats. HARACTERISTIC Sealing surface width Intake: 1,5 mm...
Page 32
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E N G I N E - CY LI NDER ASS Y. AN D T IMIN G SYS TE M NSPECTING THE VALVES NSPECTING THE VALVES - Insert the valves into the cylinder head. - Alternately test the intake and exhaust valves.
Page 33
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E NG I N E - CY LI ND ER ASS Y. A N D T IMI NG SYST EM HARACTERISTIC Minimum allowable diameter - Intake: 4,970 mm Minimum allowable diameter - Exhaust: 4,960 mm Standard clearance - Intake: 0,015 ÷...
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E N G I N E - CYLIND ER AS SY. A N D TI MIN G SYST EM NSPECTING THE CAM SHAFT NSPECTING THE CAM SHAFT - Ensure that the camshaft bearings are not abnormally worn.
Page 35
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM EN G I N E - CYLIND ER A S SY. A N D T IMIN G SYST E M - Replace any damaged parts. HARACTERISTIC Minimum allowable diameter «A»: Ø 10,970mm Minimum allowable diameter «B»: Ø...
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E N G I N E - CY LINDE R AS SY. A N D T IMIN G SYST E M - Tighten the pivot and camshaft check screw complete with the washer shown in the figure. Locking torques (N*m) Rocker-arm shaft and camshaft bearing screw: 3 - 4 Nm - To complete the fastening of the cylinder head, tighten the...
Page 37
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E N G I N E - CYLIND ER AS SY. A N D TI MIN G SYST EM - Fit the pulley on the camshaft. - Fit the belleville washer so that its outer rim is in contact with the pulley.
Page 38
ENGINE - CYLINDER ASSY. AND TIMING SYSTEM E N G I N E - CY LINDE R AS SY. A ND TIMIN G SYS TE M NSPECTING THE RADIAL AIR GAP Inspecting the kick-starter: - Using a thickness gauge, measure the two metallic protru- sions.
Page 39
ENGINE - CRANKCASE - CRANKSHAFT EN G I N E - CR ANKCAS E - CRA NK SHAFT PLITTING THE CRANKASE HALVES PLITTING THE CRANKASE HALVES - Remove the following assemblies: Transmission cover, clutch, gears, as described in the related paragraphs: «Re- moving the transmission cover», «Removing the clutch», and «Removing the gear-shafts.
Page 40
ENGINE - CRANKCASE - CRANKSHAFT E N G I N E - CR ANKCAS E - CRA N KSH AFT - Rest the flywheel-side crankcase-half on a flat surface, adequately supported and with the crankshaft vertical. - Insert the timing chain positioning it at the edge of its housing so that in won’t interfere with the refitting of the crankshaft assembly, the bearing, and the timing gear- shaft.
ENGINE - CRANKCASE - CRANKSHAFT E N G I N E - CR ANKCASE - CRAN KS HAFT EFITTING THE CRANKSHAFT EFITTING THE CRANKSHAFT - Check the connecting rod axial play. - While holding the crankshaft manually, check the connec- ting rod radial play.
ENGINE - CRANKCASE E N G I N E - CR ANKCAS E EFITTING THE CRANKCASE HALVES EFITTING THE CRANKCASE HALVES - Using a heat gun, heat the bearing housing on the transmission-side crankcase-half up to approximately 120 °C. Install the bearing and the oil conveying plate with its gasket, tightening the three screws at the prescribed torque, as shown in the figure.
Page 43
ENGINE - CRANKCASE E NG I N E - CRA NKCA S E - Lubrificare con olio motore Ie rispettive sedi come indicate in figura. Montare la guarnizione utilizzando come riferimento i due grani. - Accostare i due carter e montare Ie 10 viti e bloccare alia coppia prescritta.
ENGINE - OIL PUMP E N GI N E - O IL P UMP UBRICATION UBRICATION CRANKSHAFT OIL SEALS Removal - Extract the flywheel-side oil seal from the crank- case taking care not to damage or score the crankcase. - Pour engine oil over the oil seal and its seat in the crankcase.
Page 45
ENGINE - OIL PUMP E NG I N E - OI L P UM P Measure the distance between the outer rotor and the pump body (see figure). HARACTERISTIC Maximum allowable clearance: 0,20 mm Check the axial play of the rotors using a trued bar as shown in the figure.
ENGINE - CARBURETTOR E N G I N E - CAR BURETTOR UEL SUPPLY UEL SUPPLY REMOVING THE CARBURETTOR - In order to detach the carburettor from the engine, loosen the intake manifold and reed-valve pipe clamp screw. - To carry out further operations on the carburettor, discon- nect the throttle cable and the fuel supply tube.
Page 47
ENGINE - CARBURETTOR E NG I N E - CAR BUR ETTOR - Should anomalies be observed for these components, pro- ceed with the replacement. - Refit the throttle valve cover. - Refit the main and idling jets. - Refit the float and its conical needle. - Refit the float bowl ensuring the seal is properly positioned in its housing.
Need help?
Do you have a question about the Dirtboy 10 and is the answer not in the manual?
Questions and answers