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my 521 is backfiring now ? what could be causing it?


myfairlady

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Out the carb can be an intake valve that does not seal when closed. Cylinder fires and it gets out and back into the intake. This can be from no valve lash (too tight) to a bad face/seat seal (worn or pitted) a bent stem (not closing) damaged/broken. Excessively lean can also backfire out the carb.

 

Out the exhaust is usually an interruption of the ignition long enough for the un-burnt gas and air to be pumped into the exhaust pipe. When the ignition resumes, the un-burnt gas explodes in the pipe. This can be extremely dramatic. I have split mufflers before from this. Usually a loose wire on the primary side of the ignition system is the cause. Points in need of replacement can also do this.

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What Mike is saying is, guys this is a dead post! The person is no longer even here probably. The original post was made 2 years ago. Just some fun at Charli69's expense.

Happy 4th of July 521'ers

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