my dad just rebuilt a toasted kawi bayou300 for someone, and the kawi shop reassembled top end for us when they ordered parts, cuz they already had bottom end to clean out chunks of piston in case .
(so we assume it's in time)
but it is all back together, gets spark, etc., but won't start.
just backfires thru carb (literally, backFIRES)

can anyone give us anywhere to start that might cause this backfiring thru the carb, so that we may fix it? (remember, certified & proven/experienced kawi mechanic told us he timed it correctly)

thanks
-racer36

 

Hes capible of making mistakes too. About the only thing that causes the backfireing, is valve timing. Either the valves are grossly out of adjustment, or the cam timing is off. If he assembled it with the chain slack, on the wrong side, thatll do it. The slack needs to be on the tensioner side.

 

I second that motion. Sounds like a timing issue to me.

 

Backfire comes thru the carb - caused by either way too lean of a mixture or the air fuel charge is being fired way too soon -- After fires - often confused with backfires - come out the exhaust and are caused by way too rich a mixture or charge being fired way too late. Timing and mixture would both be a place to look.