Backfiring Kohler CH20

[Steve1972]

I have a 97 max IV with a Kohler CH20. When coming down from high RPM's to slow or idle I get backfiring. I changed out the gas and added an inline fuel filter. (there was not one already there). I also changed the plugs. Do I need a carb rebuild or is there an easier fix I should try first. I also get the feeling at full throttle that she is not getting enough gas. Is there a way to check/test the fuel pump? Thanks

[LarryW]

If it is running lean it could make the exhaust hot creating the backfire. My guess is there is something in the main jet. Usually the pump is either good or bad. Easy fix sometimes is to take the air cleaner off. Start it up and rev the crap out of it, hold your hand over the carb and let the engine bog down to almost not running or even kill it. If it does die, hold throttle wide open when cranking it back up. It flooded so wide open helps a flooded engine start. If your lucky, the extra vacuum you created will clean up any junk in the main jet. Be worth a shot. Some engines even new just backfire on deceleration. Maybe someone knows something specific to your engine.

[blue88s2003]

you got a hole somewhere or a leak somewhere in your exhaust system

[Tomo]

hi
Inlet manifold vacumn leak , spray carby cleaner fluid around where manifold connects to head . Very common issue in vtwin kohlers .

tomo