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By Thack
#38507
I think, instead of us having to guess from afar, it's time to do some proper diagnostics. Get someone to move the engine through the compression stroke while you put your ear to the exhaust port, the inlet port and the decompressor hole. If there's a major leak it'll be obvious - after all, there'll be half a litre of air coming out. If they aren't leaking then it must be either the cylinder head gasket or the piston/rings. A large dollop of oil through the plug hole should make a detectable difference if it's the rings.

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