I'm an idiot.

Weldangrind · 01-13-2011, 10:48 AM

Maybe it has a broken ring, which would certainly account for compression loss.

For the unfamiliar, if you connect an air hose to the spark plug hole, you can find where the compression is leaking. Slowly rotate the engine until it becomes obvious; air flowing out of the exhaust is a bad exhaust valve, air flowing through the carb (with the carb open) is a bad intake valve, and air flowing out of the crankcase breather tube is a bad ring.

You can either buy the adapter that screws into the plug hole or make your own. I made one by breaking the ceramic out of an old plug, removing the insulator and ground electrode and tapping the inside of the metal body to accept an air quick-connect fitting.

01-13-2011, 10:48 AM	#16
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	Maybe it has a broken ring, which would certainly account for compression loss. For the unfamiliar, if you connect an air hose to the spark plug hole, you can find where the compression is leaking. Slowly rotate the engine until it becomes obvious; air flowing out of the exhaust is a bad exhaust valve, air flowing through the carb (with the carb open) is a bad intake valve, and air flowing out of the crankcase breather tube is a bad ring. You can either buy the adapter that screws into the plug hole or make your own. I made one by breaking the ceramic out of an old plug, removing the insulator and ground electrode and tapping the inside of the metal body to accept an air quick-connect fitting. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
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