APRILIA Pegaso 650 Manual De Taller página 289

DEFECT
Engine knocks under
stress.
Engine lacks power, or
power is insufficient.
Engine overheats.
Engine shoots thick,
bluish smoke.
Engine vibrates.
Oil pressure too low.
Oil pressure too high.
Engine too noisy.
SYMPTOM AND POSSIBLE CAUSE
1) Ignition system defective.
2) Incorrect thermal value of spark plug.
3) Fuel octane rating too low.
1) Piston or cylinder segments worn.
2) Spark plug gap incorrect or faulty ignition system.
3) Carburettor jets clogged.
4) Incorrect fuel level in carburettor float chamber.
5) Air cleaner clogged.
6) Air infiltration from intake pipe.
7) Lack of valve clearance.
8) Faulty camshaft timing.
9) Decompressor does not start.
10) Valve seats defective.
11) Valve springs broken.
12) Excessive oil in engine.
1) Fuel level in carburettor float chamber too low.
2) Air infiltrations from intake pipe.
3) Unsuitable engine oil.
4) Faulty cooling system.
5) Insufficient engine oil quantity.
6) Oil pump defective or oil circuit clogged.
1) Excessive oil in engine.
2) Piston segments worn.
3) Valve rod oil seal worn.
4) Head gasket defective.
1) A bearing or a bearing housing is worn.
2) Countershaft not positioned in correspondence with signs.
1) Insufficient quantity of oil in the circuit.
2) Oil pump worn.
3) Oil pump control gears broken.
4) Low pressure circuit valve defective (remains open).
1) Low pressure circuit valve defective (remains closed).
2) Oil circuit clogged.
Noise seems to come from head.
1) Excessive valve clearance.
2) Valve springs broken.
3) Decompressor does not switch off.
4) Discharge camshaft showing end play.
5) Camshafts or camshaft seats worn.
6) Camshaft control gears worn or loose.
Noise seems to come from timing chain.
1) Chain tightener defective.
2) Chain extension too long, chain guide worn.
Noise seems to come from piston.
1) Piston or cylinder bore worn.
2) Piston or pin worn.
3) Piston segments worn or broken, or grooves worn.
REPAIRS
REMEDY
Check rotor, stator, and
unit, change defective
component.
Use spark plugs with pre-
scribed thermal value.
Use fuel with prescribed
octane rating.
Change.
Adjust or change.
Clean.
Adjust.
Clean.
Tighten or change.
Adjust valve clearance.
Adjust.
Check decompressor.
Change valves, bore the
valve seats.
Change valve springs.
Check oil nonreturn valve.
Adjust.
Tighten or change.
Use engine oil prescribed.
See radiator section
Top up oil level.
Repair and clean.
Drain excess oil, check oil
level.
Change segments.
Change oil seal.
Change head gasket.
Change bearing or worn
component.
Time the countershaft.
Top up oil level.
Replace oil pump.
Replace the gears.
Replace valve spring.
Replace valve spring.
Clean oil circuit.
Adjust valve clearance.
Change valve springs.
Change decompressor
spring.
Adjust clearance.
Change shafts or head.
Change gears or loosen
screws.
Change preload spring of
chain tightener.
Change chain or chain
guides.
Grind cylinder or change
piston, or cylinder.
Change piston or piston
pin.
Change piston segments
or complete piston.
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