Backfire on deceleration

[Craig54]

gs 1000g 1981
Bike is backfiring on deceleration
how do I work out where its sucking air??

Craig

[rapidray]

If you have a stock exhaust, airbox, & jetting, you might want to start with inspecting the intake manifolds & orings in them for leaks. If those are all ok, I would first remove the mixture screw plugs & adjust the mixture screws CORRECTLY. Second, I would shim the stock needles .040-.060 to raise them UP & richen them a little. Factory Suzuki jetting is notorious for being lean & these things I just mentioned help GREATLY! Make sure you check the carb sync after this also. Ray.

[49er]

Also check the exhaust system for gasket/air leaks.

[terrylee]

After doing all that, you might try syncing carbs., that should help. terrylee

[bwringer]

There are (or should be) some "sleeves" in the exhaust system that act as gaskets between the various pieces. If these are boogered up or missing, they can cause popping and backfiring.

If the gaskets between the cylinder head and exhaust are missing or munged, you'll hear a tapping noise, especially under load, and you can also get popping and backfiring.

All the usual checks for intake system leaks apply as well, of course... seal your airbox, good intake boots & o-rings, etc.