Troubleshooting; Engine - APRILIA RS 250 Service And Repair Manual

8 - 7MSERVICING INFORMATION

TROUBLESHOOTING

ENGINE

Complaint
Engine will not start,
or is hard to start
Engine stalls
easily
Noisy engine
Symptom and possible causes
Compression too low
1. Excessively worn cylinder or piston rings.
2. Stiff piston ring in place.
3. Gas leaks from the joint in crankcase, cylinder or
cylinder head.
4. Spark plug too loose.
5. Broken, cracked or otherwise failed piston.
6. Worn crankshaft oil seal.
Plug not sparking
1. Fouled spark plug.
2. Wet spark plug.
3. Defective ignition coil.
4. Open or short in high-tension cord.
5. Defective ignition system.
No fuel reaching the carburettor
1. Clogged air vent hole in the fuel tank cap.
2. Clogged or defective fuel cock.
3. Defective carburettor needle valve.
4. Clogged fuel pipe.
1. Fouled spark plug.
2. Defective ignition system.
3. Clogged fuel pipe.
4. Clogged jets in carburettor.
Noise appears to come from piston
1. Piston or cylinder worn down.
2. Combustion chamber fouled with carbon.
3. Piston pin or piston pin bore worn.
4. Piston ring groove worn.
5. Piston pin bearing worn.
Noise seems to come from clutch
1. Worn splines of countershaft or hub.
2. Worn teeth of clutch plates.
3. Distorted clutch plates, driven and drive.
Noise seems to come from crankshaft
1. Rattling bearings due to wear.
2. Big-end bearings worn and burnt.
3. Crankshaft bearing worn and burnt.
Noise seems to come from transmission
1. Gears worn or rubbing.
2. Badly worn splines.
3. Primary gears worn or rubbing.
Remedy
Replace.
Repair or replace.
Repair or replace.
Tighten.
Replace.
Replace.
Replace.
Clean and dry.
Replace.
Replace.
Repair or replace.
Clean.
Clean or replace.
Replace.
Clean.
Clean.
Repair or replace.
Replace.
Clean.
Replace.
Clean.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.