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1981 CB750 Custom: Oil coming out of #1 cylinder exhaust pipe

Denver Honda

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Denver, CO
Ok, we about 2 hours from the house on the highway and suddenly, poof, lots of blue smoke coming out of #1 exhaust. Made it home. Bike runs not bad, but getting oil accumulating in the #1 exhaust. Not smoking so much. Thinking it may be a bad valve (seat) or rings. Thing is, it runs now and not smoking, but still getting the oil. Any help on what it may be and fix would be good to hear.
 
Compression test, may have failed a piston. Not smoking but still passing oil says that cylinder is dead. Pull plug on that one and likely soaked.
 
Thanks for that, amc49. I can do a compression test, well, i have a compression tester that I used back in the day, so if it fits, that will be a good test. Good hint on the plug, too. So, a failed piston meaning the rings are shot or bad connecting rod bearing? May not know until the head is pulled, for sure.

Thanks, again. That will also help me decide to keep or to sell. Hate to sell it...
 
If one cylinder was dead it would very obvious. These bikes don't move well at all on 3 cylinders.

How much oil?

It could be broken or stuck oil rings, a bad valve guide, leaky head gasket, or something as simple as a valve guide seal.

If the compression is good and the plug is not oily, I'd suspect the seals.
 
Another oddity................if slowly oiling out it can build up in pipe to then accumulate and then harder long drive builds enough heat to light all that off, you then get a smoker for a while until the oil burns back down again.
 
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