cb550f fouls (1)plug quickly

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i own a 74 cb550f. i noticed that it fouls the number one plug after a few minutes of riding. there is oil coming from around the exaust on the cylinder block. the valve stem seals are fine and the oil ring is fine. where is the oil coming from?!? i'm bent over backwards. do i have a bad cylinder block or maybe a head?

-- brian studt (brains@iastate.edu), March 06, 2002


Hey, Brian,

How's things in Ames? I bought my first 550k in Ames in 1983, my freshman year. Totalled it in '85, rebuilt in '86...ah, memories...

Have you done a compression test on that cylinder? How do you know your rings and/or valve stem seals are good?

The oil on the outside of the block could be either a bad head gasket or it could be leaking from around the rubber pucks that close the holes over the stud bolts. OR it's REALLY puking from the inside out.

It could be a cracked/perforated piston, as well, I suppose.

Are you sure the plug is oil-fouled or is it just running really rich on that cylinder? Have you cleaned/adjusted/balanced the carbs recently? It could be that you have 2 separate problems: a carb/cylinder that needs to be "leaned out" and and exterior oil leak.

Do you have a repair manual?

Let me know more.

Good luck (and GO 'CLONES!! Well, maybe next year...)


-- matt reinet (mjreinert@prodigy.net), March 06, 2002.

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