I have a GX340 on a belt drive washer,bout 10 years old .I can run it 10 min.and then its starts to bog down,lose power and spit fire out the muffler.I checked carb, filters,valve gap,gas,everything I could think of..... I'm lost???

dont know where you are but i got 6.5 hp b&s used maybe 4 time s
its on powerwasher manifold cracked if close enough ill give u a good deal

Have you tried loosening the gas cap when it begins to bog down? Could be a clogged vent!

That would cause the motor to die,it continues to run spitting and sputtering while blowing fire out the mufffler.Could I have a burnt exhaust valve?