Cylinder Head/Valves Troubleshooting; Excessive Smoke; Excessive Noise; Rough Idle - Honda CRF110F Service Manual

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TROUBLESHOOTING
CYLINDER HEADNALVES
Engine lop-end problems usually affect engine performance. These problems can
be
diagnosed
by
a compression lest or by
tracing engine noises to the top-end with a sounding rod stethoscope.
If the performance is poor at low speeds, check for white smoke in the crankcase breather hose. If the hose is smoky, check for
a seized piston ring (page 9-6).
Compression too low, hard starting or poor performance at low speed
Valves:
- Incorrect valve clearance
- Burned or bent valves
- Incorrect valve timing
- Broken valve spring
- Valva stuck open
Cylinder head:
- Uneven valve sealing
- leaking or damaged cylinder head gasket
- Warped or cracked cylinder head
Worn cylinder, piston or piston rings (page 9-5)
Compression too high , overheating or knocking
• Excessive carbon buiid·up on piston head or combustion chamber
Excessive smoke
Cylinder head:
- Worn valve stem or valve guide
- Damaged stem seal
Worn cylinder, piston or piston rings (page 9·5)
Excessive noise
Cylinder head:
- Incorrect valve clearance
- Sticking valve or broken valve spring
- Damaged or worn camshaft
- Loose or worn cam chain
- Worn or damaged cam chain guide roner/sprocket
- Worn or damaged cam chain tensioner
- Worn cam sprocket teeth
- Worn rocker arm andlor shaft
Worn cylinder, piston or piston rings (page 9-5)
Rough idle
low cylinder compression
• Faulty fuel system (page 6-4)
8-5