Backfire

[mlempenau]

I have a backfire on the left side of my 79 xs11. It happens when I am idling cold or hot and when I back off the throttle either cold or hot. I have a color tune kit and it seems to be coming from the #1 Cylinder??? I have tried changing the idle mixture with no help. I also changed the idle mixture on the #2 Cylinder. I'm kinda blank. Can't think of what to do next? Any help. Thanks,

[Dragonrider]

Check the exhaust system on that side for air leaks/loose connections, bad gaskets. Air leaking into exhaust can cause these symptoms.

[crunchbird]

I've had it left and right, coming and going:

I had the muffler break off the pipe on the left, that made a small amount of backfiring, and also the carb coughed, which went away when fixed.

I had a broken float post on the right #3 that caused backfiring like crazy. Too much fuel flooding into the carb, plug very sooty. I was setting off car alarms up and down the street on that one! I would think anything wrong with the float/valve/O ring would cause it.