Cylinder Head/Valves Troubleshooting; Troubleshoo Ting - Honda 2003 NPS50 Ruckus Service Manual

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TROU BLESHOOTING
Engine top-end problems usually affect engine performance. These problems can be diagnosed by a compression test
or by tracing engine noises to the top-end with a sounding rod or stethoscope.
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If the performance is poor at low speeds, check for white smoke in the engine breather drain hose. If the hose is smoky,
check for a seized piston ring (page 1 3-8).
Compression too low, hard starting or poor performance at low speed
Valves:
- Incorrect valve clearance
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- Burned or bent valve
- Incorrect valve timing
- Broken valve spring
- Uneven valve seating
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Cylinder head:
- Leaking or damaged head gasket
- Warped or cracked cylinder head
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- Loose spark plug
Worn cylinder, piston or piston rings (page 1 3-8)
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Compression too high, overheating or l<nocking
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Excessive carbon build-up on piston head or on combustion chamber
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Excessive smoke
Worn valve stem or valve guide
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Damaged stem seal
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Worn cylinder, piston or piston rings (page 1 3-8)
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Excessive noise
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Incorrect valve clearance
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Sticking valve or broken valve spring
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Worn or damaged camshaft
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Worn or damaged cam chain
Worn cam sprocket teeth
Worn rocker arm and/or shaft
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Worn or damaged cam chain tensioner
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Worn cylinder, piston or piston rings (page 1 3-8)
Rough idle
Low cylinder compression
Incorrect carburetor setting {page 6-3)
CYLINDER HEAD/VALVES
9-5