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1978 cb750 four leaking oil and gas mix

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benito1977

1978 cb750 four leaking oil and gas mix

Any help would be appreciated. Here is the video link:
http://m.youtube.com/watch?v=vYER2xwzUgc

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Re: 1978 cb750 four leaking oil and gas mix

Administrator

That bike sounds like crap.

I would be more concerned with the knocking right now. As for the leak, I could not see anything in the video, and now I am dizzy from watching it.

In order to figure this out, first you must figure out if it is gas, or oil. There is only one way you could get both from the same leak, and that would be if you filled the crankcase with gas, and it had a leak.
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1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
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Re-run

Re: 1978 cb750 four leaking oil and gas mix

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Yeah I wonder about the engine noise too. It is also running too low rpm at idle. I know when the engine chugs like this, it can make additional noise. Part of it may just be the built in camera/phone mic.

You need to lay something under the bike, something like a few paper towels that can catch part of the leak.

You need to be able to smell it and see the color. It may just be fuel coming out of the overflow tubes and the tubes are too short or deteriorated enough that they may be cracks or holes in the lines.

The ride IS the adventure. The destination is just to get gas!

TuneAfish

Re: 1978 cb750 four leaking oil and gas mix

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shinyribs

Re: 1978 cb750 four leaking oil and gas mix

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tuneAfish wrote

Just listened on good speakers and it sounds to me like you may have a hole in a piston, did you have the valve lash adjusted recently?

If there was a hole in a piston it would be, literally, pumping oil out of the tail pipe.

Sounds like your primary chain is crazy loose. May need a tensioner. Hard to really say just by listening. Doesn't sound like cam chain at all. Could just be clutch rattle (typical/normal) and the camera mic is just making it sound worse than it really is. Either way, if you can determine that it's NOT clutch rattle, I'd drop the pan and look at the primary chain before I ran it any more.

As far as your leak...well, I didn't know where to look and I didn't hear your leak either.

Where are you seeing a leak at?