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81 cb750c engine died, help!

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slash360

81 cb750c engine died, help!

I've got an 81 cb750c, been riding it for years with no major problems. Recently while riding a rattling /grinding sound came from motor, it cut off and I trailered it home.Engine turns over but won't start. I need some advice on troubleshooting. I have some mechanical ability,but never been inside motor.Any help would be appreciated. Thanks, Steve

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Re: 81 cb750c engine died, help!

Administrator

This could be any number of things, so lets start at the electrical system which is known the be problematic on the DOHC bikes. Does the battery have a charge? Does it crank the engine over, or are you turning it with a wrench?
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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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shinyribs

Re: 81 cb750c engine died, help!

Administrator

From the description of the sounds I'm thinking it may have tossed a cam chain.

slash360

Re: 81 cb750c engine died, help!

battery good, starter working. took off valve cover , cam chain intact. thought it may have broke. Could it have jumped time?

shinyribs

Re: 81 cb750c engine died, help!

Administrator

Its possible. Does the chain seem to have enough slack to allow that? Might wanna take a look at your tensioners. There's also a guide rail in there for the main cam chain.

The FSM (Factory Service Manual) is available for free download on the homepage. It only takes a minute or two for it to download. It will help you have a better understanding of what all is inside your engine.