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38

I

NSPECTING

 

THE

 

RADIAL

 

AIR

 

GAP

Inspecting the kick-starter:

- Using a thickness gauge, measure the two metallic protru-
sions. Values: 0.2 ÷ 0.3 mm.

- Ensure the pick-up air is between 2.0 and 2.6 mm

- The pick-up refitting procedure does not include the adjust-
ment of the air gap.

- Values different from the above, are due to deformations of 
the pick-up mounting bracket.

Locking torques (N*m)

Stator/mounting bracket fixing screws: (M4x16) 2 ÷ 3 Nm 
Pick-up/flywheel-side halfcrankcase fixing screws: (M6x16) 
8 ÷ 10 Nm Mounting bracket for stator assy ./flywheel-side 
half-crankcase fixing screws: (M6x20) 8 ÷ 10 Nm Flywhe-
el  fixing  flanged-nut:  (M10x1,25)  15  Nm  Flywheel  cover/ 
flywheel-side half-crankcase fixing screw: (M5x20) 2,5 ÷ 
3 Nm. 

Follow the removal operations in the reverse order, tighte-
ning the four screws with the prescribed torque.

N.B.

FIT A NEW 0-RING ON THE ROCKER-ARMS COVER.

Locking torques (N*m)

Head cover screw: 8 ÷ 10 Nm

ENGINE 

EE

- CYLINDER ASSY. AND TIMING SYSTEM

ENGINE 

- CYLINDER ASSY. AND TIMING SYSTEM

R

EFITTING

 

THE

 

ROCKER ARMS

 

COVER

S C

G

 

 

   

G

Summary of Contents for Dirtboy 10

Page 1: ...MINIMOTO 50 C C 4T WORKSHOP MANUAL...

Page 2: ...rand 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...

Page 3: ...DER PISTON SMALL END INSPECTING THE CYLINDER HEAD DISTRIBUTION CHAIN VALVES INSPECTING THE CAM SHAFT REFITTING THE TIMING CHAIN ASSEMBLING THE TIMING CHAIN TENSIONER REFITTING PICK UP REFITTING CARTER...

Page 4: ...ons requiring special tools use only those specifically designed for this engine Always replace seals gaskets and split pins with new ones when refitting new or old components After removal clean the...

Page 5: ...5 x 10 3 00 x 10 2 50 x 12 3 00 x 10 Front suspension 120mm travel hydraulic fork 135mm travel hydraulic fork 160mm mechanical disk 90mm mechanical drum Front brake Rear brake Rear suspension 140mm t...

Page 6: ...41 8 mm 49 93 mm 11 5 12 5 1 PHVA Champion RG 4 HC overhead single camshaft two valves chain controlled on l h side 0 10 mm en cold 0 10 mm en cold Engine lubrication by chain driven lobe pump in cran...

Page 7: ...e fixing screws Head cover screw Oil pump crankcase fixing screws Intake manifold fixing screws Carburettor manifold clamp screw Starter motor fixing screw Flywheel cover fixing screw Transmission cov...

Page 8: ...Every 3 month Every 3 month Every 6 month Every 6 month Every engine oil replacement At 5 hours or 1 month At 5 hours or 1 month At 5 hours or 1 month At 5 hours or 1 month At 5 hours or 1 month At 5...

Page 9: ...HARACTERISTICS Recommended spark plug Champion RG 4 HC MAINTENANCE M M MAINTENANCE MAINTENANCE CHART ACTION FREQUENCY Engine oil Replacement Idle speed Fuel Change Filtro aceite Sustituci n Valve clea...

Page 10: ...fter draining the oil clean the gauze strainer with a suitable solvent and then blow it with compressed air To gain access to the gauze strainer remove plug A see figure Refit the strainer and tighten...

Page 11: ...ucts AGIP CITY 4 T Synthetic oil 20W40 The oil level must be at the lower edge of the filler cap Therefore before starting the cold engine it is necessary to check the oil level using the inspection h...

Page 12: ...reference marks as for the valve timing point described earlier Using a thickness gauge ensure the clearance between the valve and the valve adjuster is within the indicated values If the valve cleara...

Page 13: ...e the manometer and refit the components following the removal procedure in the reverse order If the pressure is below the min allowable pressure check the engine speed in test conditions If this is t...

Page 14: ...g in the crankcase and the return spring Replace any damaged part Refit the toothed segment as show in the figure pre loading the spring by hand REMOVING THE ENGINE PINION Using the special tool retai...

Page 15: ...ION DO NOT USE TOOLS TO OPEN THE MASSES SO TO AVOID LOAD VARIATIONS IN THE SPRINGS INSPECTING THE CLUTCH DRUM Check that the clutch bell housing is not worn or damaged Measure the inside diameter of t...

Page 16: ...gio 40 44 Nm END GEAR SHAFT Insert the chain gear shaft and secure with its circlip as shown in the figure REFITTING THE TRANSMISSION COVER Refit the gasket new Refit the cover tightening the seven sc...

Page 17: ...G Restrain the rotation of the flywheel using the special tool Remove the M10X1 25 flanged nut Extract the flywheel with the specially designed extractor Specific tooling 020565Y Compass flywheel stop...

Page 18: ...N THE OIL BREATER TUBE REMOVING THE TIMING SYSTEM DRIVE Remove the chain tensioner central screw together with its spring washer and O ring Loosen the chain tensioner central screw and remove it with...

Page 19: ...KE Specific tooling 020565Y Compass flywheel stop spanner REMOVING THE CAM SHAFT Remove the bearing check screw shown in the figure Remove the camshaft complete with the bearing using the specific too...

Page 20: ...in the figure Loosen the four cylinder head locknuts in two or three phases following a crosswise pattern Remove the cylinder head the two dowel bolts and the gasket N B SHOULD IT BE NECESSARY THE HE...

Page 21: ...Remove the cylinder minding the aligning pin on the crank case Remove the cylinder base gasket CAUTION TO AVOID DAMAGING THE PISTON SUPPORT IT WHILE REMOVING THE CYLINDER Remove the two circlips the...

Page 22: ...ax allowable diameter 13 030mm INSPECTING THE WRIST PIN Measure the piston pin outside diameter CHARACTERISTIC Standard diameter 13 0 0 004 mm Minimum allowable diameter 12 990 mm Calculate the mating...

Page 23: ...ndard cylinder diameter 39 024 38 996 Maximum allowable runout 0 05 mm Pistons and cylinders are classified according to diameter Mating is obtained by matching class letters A A B B C C D D INSPECTIN...

Page 24: ...height 57 15 0 15 Cylinder base gasket thickness 0 5 Measured value 0 40 0 25 Gasket thickness 0 25 0 05 Measured value 0 25 0 05 Gasket thickness 0 35 0 05 Carefully clean the piston ring grooves us...

Page 25: ...cylinder axis Using a thickness gauge see figure measure the gaps of the piston rings If any measurements are greater than prescribed replace the piston rings ENGINE E E CYLINDER ASSY AND TIMING SYST...

Page 26: ...EW PISTON RINGS USED IN COMBINATION WITH A USED CYL INDER MAY HAVE DIFFERENT BEDDING CONDITIONS THAN THE STANDARD STANDARD GAP MAXIMUM GAP ENGINE E E CYLINDER ASSY AND TIMING SYSTEM ENGINE CYLINDER AS...

Page 27: ...the circlip into the tool by means of the drift Rest the tool on the piston taking care that the side with the 90 bevel always faces upwards as shown in the figure Fit the piston pin circlip using th...

Page 28: ...HE CYLINDER FOR THIS REASON IT IS IMPORTANT THAT THE RINGS SHOULD BE FITTED WITH THE T FACING UPWARDS STAGGER THE PISTON RING GAPS BY 120 DE GREES AS SHOWN IN THE FIGURE LUBRICATE THE PARTS WITH ENGIN...

Page 29: ...AREFULLY BLOW THE LUBRICATION DUCT AND OIL THE CYLINDER BARREL Specific tooling 020288Y Fork for fitting piston to cylinder Locking torques N m Timing chain tensioner screw 8 10 Nm INSPECTING THE CYLI...

Page 30: ...e assembly Removing the central screw with the O ring and the chain tensioner spring Ensure the unidirectional mechanism is not worn Check the condition of the tensioner spring If any worn components...

Page 31: ...direction EXHAUST GUIDE INTAKE GUIDE If the width of the impression on the valve seat or the dia meter of the valve guide exceed the prescribed limits repla ce the cylinder head Measure the width of...

Page 32: ...t or if any bending or gaps are noted replace the valve If no anomalies are found during the above checks the same valves can be reused For best sealing results it is advisable to grind the valves Gri...

Page 33: ...caps and the cotter halves show no signs of abnormal wear REFITTING THE VALVES Lubricate the valve guides with graphitized oil Position the valve spring lower caps on the cylinder head Using the spec...

Page 34: ...12 0 002 0 010 mm Standard diameter Bearing B 16 0 015 0 023mm Minimum allowable diameter Bearing A 11 98mm Minimum allowable diameter Bearing B 15 96 mm Standard height Intake 25 935 mm Standard hei...

Page 35: ...gasket with the same thickness as the old one Insert the cylinder holding down studs into the cylinder head and tighten the four locknuts with a torque indicate N B REPLACE THE CAMSHAFT BEARING WITH A...

Page 36: ...90 FoIlo wing the order indicated REFITTING THE TIMING CHAIN N B SEE REFITTING THE TIMING CHAIN TO BE CARRIED OUT BEFORE RECOUPLING THE HALFCRANKCASES Insert the spacer on the camshaft Using the mark...

Page 37: ...screws shown in the figure Specific tooling 020565Y Compass flywheel stop spanner Locking torques N m Camshaft pulley screw 12 14 Nm Head cover screw 8 10 Nm Set the tensioner slider in its home posit...

Page 38: ...screws M4x16 2 3 Nm Pick up flywheel side halfcrankcase fixing screws M6x16 8 10 Nm Mounting bracket for stator assy flywheel side half crankcase fixing screws M6x20 8 10 Nm Flywhe el fixing flanged n...

Page 39: ...graphs Remove the ten half crankcase coupling screws Split the crankcase halves with the crankshaft remaining installed in the flywheel side half Remove the crankshaft by heating the halfcrankcase up...

Page 40: ...the three points shown in the figure Check the condition of the crankshaft cone the tab seat the oil seal bearing the knurled pin and the threaded tangs If any anomalies are found replace the cranksh...

Page 41: ...ing rod vertically as shown in the figure Check that the surface of both crankshaft halves is not sco red Using a calliper measure the width of the crankshaft as shown in the figure CHARACTERISTIC Sta...

Page 42: ...he chain gear shaft Refit the oil pump on the crankcase and secure it by tightening the two screws with the prescribed torque Install the two locating pins preferably on the transmission side crankcas...

Page 43: ...icate 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 Locking torques N m Half crankcase joining...

Page 44: ...c tooling 020340Y Flywheel side oil seal fitting drift Oil pump OIL PUMP INSPECTION Remove the two oil pump fixing screws Remove the inner rotor circlip Remove the rotors and carefully clean them with...

Page 45: ...BODY PLANE CHARACTERISTIC Maximum allowable clearance 0 09 mm Check that the pump cover is not worn or scored If any measurement is not as specified or if any part is scored replace the part or the a...

Page 46: ...hrottle valve cover paying attention to the attached components throttle valve conical needle and return spring CAUTION DO NOT ATTEMPT REMOVING COMPONENTS ATTACHED TO THE CARBURETTOR BODY SUCH AS FUEL...

Page 47: ...the float and its conical needle Refit the float bowl ensuring the seal is properly positioned in its housing WARNING TO AVOID DAMAGE DO NOT INSERT METAL OBJECTS IN THE CALIBRATED SECTIONS ENGINE E E...

Page 48: ...create by w w w ciandisseny com...

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