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3787 Views 5 Replies 6 Participants Last post by  Shawn Manz

What causes backfiring? My 76 Olympique 300 was running great but yesterday after about 30 min. of riding the engine started to backfire under accelleration - it wasn't as bad up on a stand though but it will still backfire and bog. I replaced the plugs and put a new primer line on it and it is also getting gas. Does a mixture that is too lean cause backfiring? A bad coil? Thanks
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Could be a few things!

A bad coil will do it.

First thing though I would check all wires for breaks, or shorting out. Be sure to check the kill switch, or unplug it and then try the engine again.

Running lean will do it too. Check your jets to make sure they're clean. Also check the gaskets around the intake of the engine for an air leak.

probably cdi. had the same problem on my 1980 jag 2000
Try Running the sled after its warmed up and then hit the kill switch then pull the pulls see how they look are they wet or is one to white also see if puld wrires are arcing.
I woud check the compression. My two cents. not
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