Derbi Dirtboy 10, Dirtkid 12 Workshop Manual

WORKSHOP MANUAL

MINIMOTO 50 C.C. 4T

NACIONAL MOTOR, S.A., manufacturer of DERBI motorcycles and mopeds, has produced this manual with

PREFACE

the aim of documenting and simplifying as much as possible the work you need to do to in dismantling and assembling the MINIMOTO 50 c.c. 4-stroke engine.

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.

All the information included in this manual is based on the latest data available at the time of its publication. The drawings and photographs in this manual are for reference purposes only, and may therefore not be exactly the same as the corresponding parts of the current model itself.

NACIONAL MOTOR, S.A.U.

1

INDEX

GENER AL INFORMATION

Pág. 4

CARACTERISTICS

TIGHTENING TORQUES

MAINTENANCE

MAINETANCE CHART

ENGINE OIL

DISTRIBUTION

DISTRIBUTION - COMPRESSION

MOTOR

TRANSMISSION

CLUTCH

END GEAR SHAFT

STATOR-FLYWHEEL

REMOVING THEROCKER - ARMS COVER

CAM SHAFT

CYLINDER HEAD - VALVES

Pág. 5-6

Pág. 7

Pág. 10

Pág. 10-11

Pág. 11

Pág. 13

Pág. 14

Pág. 15

Pág. 16

Pág. 17

Pág. 18

Pág. 19

Pág. 20-21

CYLINDER - 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

REFITTING CRANKSHAFT

REFITTING THE CR ANKASE HALVES

OIL PUMP

CARBURETTOR

Pág. 21-28

Pág. 29

Pàg. 30-33

Pág. 34-36

Pág. 36-37

Pág. 37

Pág. 38

Pág. 39

Pág. 39-41

Pág. 42-43

Pág. 44-45

Pág. 46-47

3

GENERAL INFORMATION

This section describes the general safety rules and service recommendations to be observed.

- 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; Never run the engine in an enclosed space; exhaust gases are toxic.

- Petrol is extremely flammable and, under certain conditions, may be explosive. Do not smoke and do not allow live flames or sparks in the work area.

- Use genuine PIAGGIO spare parts and recommended lubricants. Use of non-genuine spare parts may damage the engine.

- For operations 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 components with a non-flammable or high flash-point solvent. Lubricate all contact surfaces and inspect taper fit couplings, before refitting.

- After refitting, ensure all components have been correctly fitted and work properly.

- Use only metric-sized tools for removing, repairing and refitting operations. Metric screw fasteners, nuts and bolts are not interchangeable or compatible with Imperial-sized fasteners. Use of Imperialsized tools or fasteners may damage the engine.

- For engine repairs involving the electric system, carefully inspect the refitting of the connections.

4

CHARACTERISTICS

DIRTBOY 10

DIRTKID 12

CHASSIS, WHEELS AND BRAKES

CHASSIS CODE

ZEMMR4CC24 ¿AXXXXXX?

ZEMMS4CC64 ¿AXXXXXX?

Frame Steel

Fork

Inner tube

Tyre

Front suspension

Rear suspension

Front brake

2,5 x 10”

3,00 x 10”

120mm travel

hydraulic fork

140mm

travel pneumatic

shock absorbers.

160mm mechanical disk.

Steel

ENGINE CODE

C391M ¿XXXX?

2,50 x 12”

3,00 x 10”

135mm travel

hydraulic fork

160mm

travel pneumatic

shock absorbers.

DIMENSIONS

Rear brake

Total lenght

Total width

Distance between axles

Seat height

Fuel tank capacity

Weight

90mm mechanical drum.

1290mm.

590mm.

905mm.

610mm.

44Kg.

1430mm

590mm

995mm

685mm

2,3L.

47Kg.

5

CHARACTERISTICS

SPECIFICATION

Engine

Bore per stroke

Displacement

Compression ratio

Carburettor Dell’orto

Recommended spark plug

Timing system

Valves play: induction

Valves play: exhaust

Lubrication

Fuel system

Transmission

Max. power

Engine oil

Grear-shaft teeth

DESC. / QUANTITY

Four-stroke mono-cyl-inder

39 x 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)

Engine lubrication by chain-driven lobe pump (in crankase) with gauze strainer and centrifugal filter.

Gravity, unlead petrol (minimum octane number 95), through carburettor.

Automatic wet clutch and gear reducer.

3,3 Kw (4,6 CV ) 8500 rpm.

Capacity: ~ 600c.c.

10

Gearing retio

Transmission

6

1 / 4,1

SPECIFICATION DESC. / QUANTITY

Automatic wet clutch and gear reducer.

TIGHTENING TORQUES

NAME

Spark plug:

Head cover screw

Head-cylinder stud nut

Head-cylinder / crankcase fixing screw

Chain-tensioning pad screw

Timing chain tensioner screw

Timing chain tensioner central screw

Camshaft pulley screw

Rocker-arm shaft and camshaft bearing screw

Rocker-arm adjusting nuts

Engine oil pre-filter cap

Oil drain cap

Flywheel nut (electric starter version)

Stator screws

Pick-up screw

Mounting bracket / crankcase (flywheel side) fixing screws

TORQUE IN Nm

10 ÷ 15 Nm

8 ÷ 10 Nm

6 ÷ 7 + 135º+90º Nm for first fitting, 6 ÷ 7 90º+90º Nm for refitting/locking

8 ÷ 10 Nm

5 ÷ 7 Nm

8 ÷ 10 Nm

5 ÷ 6 Nm

12 ÷ 14 Nm

3 ÷ 4 Nm

7 ÷ 9 Nm

25 ÷ 28 Nm

40 ÷ 44 Nm

2 ÷ 3 Nm

8 ÷ 10 Nm

Oil pump /crankcase fixing screws

Intake manifold fixing screws

Carburettor manifold clamp screw

Starter motor fixing screw

Flywheel cover fixing screw

Transmission cover fixing screw

Oil conveying plate fixing screws (half-crankcase transmission side)

Half-crankcase joining screws

When installing new studs, proceed as follows

7

2 ÷ 3 Nm

7 ÷ 9 Nm

1,5 Nm

11 ÷ 13 Nm

2,5 ÷ 3 Nm

8 ÷ 10 Nm

6 ÷ 7 Nm + 135º + 90º following a diagonally crosswie sequence.

MAINTENANCE

ACTION

Engine Oil - Level Check/Top up

Spark plug/electrode gap - Check

Air Filter - Cleaning

Idle speed / Fuel - Adjust

Acceleration command - Adjustment

Clutch - Check

Oil filter - Clean

Engine oil - Replacement

Engine Oil - Level Check/Topup

Spark plug/electrode gap - Check

Idle speed / Fuel - Change

Oil filter - Clean

Oil filter - Replacement

Air Filter - Cleaning

FREQUENCY

Every 3 month

Every 6 month

Every engine oil replacement

At 5 hours or 1 month

Valve clearance” Check

Idle speed / Fuel - Adjust

Acceleration command -Adjustment

Clutch - Check

Eletrical system - Check

Engine oil - Replacement

Idle speed / Fuel - Change

Oil filter - Replacement

Valve clearance - Check

Clutch - Replacement

Eletrical system - Check

Engine oil - Replacement

8

At 5 hours or 1 month

At 20 hours or 6 month

At 40 hours or 12 month

At 60 hours or 18 month

MAINTENANCE

ACTION

Engine oil - Replacement

Idle speed / Fuel - Change

Filtro aceite - Sustitución

Valve clearance - Check

Clutch - Replacement

Eletrical system - Check

Engine oil - Replacement

Idle speed / Fuel - Change

Oil filter - Replacement

Valve clearance - Check

Clutch - Replacement

Eletrical system - Check

FREQUENCY

At 80 hours or 24 month

At 40 hours or 12 month

At 100 hours or 30 month

At 120 hours or 36 month

The spark plug inspection must be carried out with the engine cold and as described below:

- Detach the spark plug cap at the end of the HT cable.

- The spark plug must be unscrewed using the supplied box spanner.

- Carefully inspect the insulator; replace if dented or damaged.

- Measure the spark gap using a suitable thickness gauge and, if necessary, adjust it by carefully bending the outer electrode.

- Ensure the seal washer is in good conditions.

- Refit the spark plug by screwing it in carefully by hand, and then locking it with the supplied box spanner.

CHARACTERISTICS

Recommended spark plug

Champion RG 4 HC

9

G

MAINTENANCE

M

MAINTENANCE

ELECTRICAL CHARACTERISTICS

Distance between electrodes

0.8 ÷ 0.9 mm

RED

EARTH

BLACK

EARTH

Locking torques (N*m)

Spark plug: 10 ÷ 15Nm

EN

INE OIL

REPLACEMENT

YELLOW

55 ± 10%

Infinite

BROWN

100 ± 10%

EARTH

Infinite

EARTH

0-1

Renew the oil when the engine is hot. Place a container under the oil sump and remove the oil drain plug. After 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 the oil plug with the prescribed torque using a new O-ring.

10

A

MAINTENANCE

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; THIS MUST ALWAYS BE AT THE LOWER EDGE OF THE INSPECTION HOLE.

N.B.

WHEN REPLENISHING FOR THE FIRST TIME, OR AFTER AN OVERHAUL, POUR IN 600 CC OF ENGINE OIL. IN ALL OTHER CASES USE 550 CC AND IF NECESSARY TOP UP.

Recommended products

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 hole on the RHS engine cover.

CHARACTERISTIC

Engine oil Capaciity: ~ 600c.c.

Turn the magnetic flywheel in a clockwise direction until the mark on it is lined up with the reference mark on the Pickup/Stator bracket, as shown in the figure, always bearing in mind that the mark on the magnetic flywheel is the reference for the first magnet (in a clockwise direction).

11

MAINTENANCE

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.

HECKING THE VALVE CLEARANCE

In order to carry out the inspection of the valve clearances, align the 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 clearance values differ from those shown below (for intake and exhaust respectively), proceed with the adjustment, by loosening the counter nut and then, with the aid of a screwdriver, loosening or tightening the adjusting screw as shown in the figure.

CHARACTERISTIC

Valves play:

induction 0,10mm (cold)

Valves play:

exhaust 0,15mm (cold)

Locking torques (N*m)

Rocker-arm adjusting nuts: 7 ÷ 9 Nm

12

CO

SSU

MAINTENANCE

HECKING THE END

- 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.

- Crank the engine using the starter motor and with the carburettor fully opened, as long as the manometer reading has stabilized. If the pressure is within the prescribed limits, remove 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 too low, check the starting system, if this is acceptable, or slightly faster, ensure the proper cylinder base gasket is installed, and inspect the sealing of the thermal components (piston rings, valves, head, timing system, etc.).

CHARACTERISTIC

Compression pressure

Min allowable value: 10,5 Kgr

MPRESSION PRE

RE

Engine revs: ~ 630 rpm (starting speed).

Locking torques (N*m) Tightening torque ~ 10 ÷15 M m

13

SMISSIO

CO

ENGINE

AUTOMATIC TRANSMISSION

TRAN

- 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.

- Search for excessive wear in the toothed segment, the toothed segment shaft, the gear shaft and its housing 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.

N

VER

- Using the special tool, retain the engine gear shaft.

- Remove the lock nut and then the gear shaft.

Specific tooling

020288Y Gear shaft retaining tool

- Remove the clutch masses with their gear.

- Remove the two circlips so to free the clutch masses.

- Ensure the teeth are not deformed and/or worn.

14

ENGINE

- 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.

N.B.

WHILE RUNNING-IN, THE MASSES SHOULD SHOW A CENTRAL CONTACT SURFACE AND MUST DIFFER ONE FROM THE OTHER. DIFFERENT CONDITIONS MAY CAUSE A CLUTCH GRABBING PHENOMENON.

CAUTION

DO NOT USE TOOLS TO OPEN THE MASSES, SO TO AVOID LOAD VARIATIONS IN THE SPRINGS.

- Check that the clutch bell housing is not worn or damaged.

- Measure the inside diameter of the clutch bell housing.

N.B.

CHECK THE ECCENTRICITY OF THE CLUTCH DRUM AND ITS KEYING: M AX 0.15 mm.

CHARACTERISTIC

Standard value:

Ø 92 +0,2 -0 mm

Max allowable value:

Ø 92,3 mm

EMOVING THE CLUTCH

- Lock the clutch bell housing with the specific tool.

- Remove the nut, the clutch bell housing and the whole of the driven pulley assembly.

Specific tooling

020565Y Compass fly wheel stop spanner

15

Derbi Dirtboy 10, Dirtkid 12 Workshop Manual

Specifications and Main Features

Frequently Asked Questions

User Manual