backfiring and popping through exhaust

[wyostateman]

just bought a 1981 1100 special and it backfires extremely when deaccelerating and pops through the exhaust while idling and sometimes while cruising. would love any help i could get as this is the first 4 cyl/4 carb bike i have ever owned or worked on

[kf4anm]

PIPES

I had a similar problem with my xj. In my case I found several holes that had rusted in my exhaust pipes. the air was detonating the fuel vapors before they were released. a little fuel tank repair putty to seal them and my backfires has been cut down considerably. The next step would be checl your carbs, i'm sure one of the other more experienced carb guru's can help you there.

cheers daryl

[dragxs11]

also valves in need of adjustment will cause such a symptom.
Matt

[MartyA]

Stick with it, it can be frustrating and fun.

Mine popped off throttle a lot, some here offer the opinion that it is running a little lean. I just had my head off and cleaned tons of carbon from the combustion chamber. I changed nothing else except when I put the cams back in I made sure they were accurately aligned, so the cam/valve timing might be just a little better. But now it does not pop while decelerating.

Definitely check the timing. And check your pickup coil wires. And check your float level. And carb boots. And air cleaner. And jet configuration. And vaccuum advance. And check all the tips here, LOTS of information. You can search this site also. Many of us have experienced what you are experiencing now, and some things you have yet to experience.

But do ask, there are lots of friendly folk here willing to help.

[GtrMn]

Pilot jets being too lean will do that too.