backfire

[colarue]

I have a 2009 gas yamaha, whe I let off the gas it backfires. What is the problem/

[smallblock450sl]

Originally Posted by colarue

I have a 2009 gas yamaha, whe I let off the gas it backfires. What is the problem/

I've seen a couple of things that cause them to back fire. #1-accelerator cable #2 (from govenor to carb throttle shaft) to tight, not alowing the throttle shaft to close all the way. #2- the muffler header pipe (at the cylinder head flange or were the header tube is welded at the muffler) are damaged. #3- the 2 12mm nuts that hold the air cleaner box and carb are loose.