6. CYLINDER HEAD/VALVES Pulsar CK 125 TROUBLESHOOTING · The poor cylinder head operation can be diagnosed by a compression test or by tracing engine top-end noises. Poor performance at idle speed White smoke from exhaust muffler · Compression too low · Worn or broken valve stem or valve guide · Damaged valve stem seal Compression too low · Incorrect valve clearance (too small) · Burned or bend valves Abnormal noise · Incorrect valve timing · Incorrect valve clearance (too large) · Broken valve spring · Burned valve or rocker arm · Poor valve and seat contact · Worn camshaft or cam follower · Leaking cylinder head gasket · Warped or cracked cylinder head · Poorly installed spark plug Compression too high · Excessive carbon build-up in combustion chamber or on piston head 6-3