Hi I have an engine that backfires when going from high idle to low idle quickly
new carb, plug anything else I can do?

Is it backfiring blowing out the carburetor, or is it blowing out the exhaust?

Seems to be blowing out the exahust

That is fairly normal when an engine slows down rapidly, fuel fed through the low speed circuit does not ignite in the cylinder, but sometimes will in the muffler causing the loud pop.

30YearTeck is right on - What helps the most is to let it idle for a moment befor turning it off. AND make shure the oil is clean . :thumbsup:

Even with the fuel-shutoff solenoid and following the cool-down process generally recommended, my CH-18 Kohler Command still does it from time to time, especially after a mowing run.

Usually doesn't do it after simply tooling around the yard.

Normal or not, this can't be good for mufflers :)

-Larry

No, I don't think it's good for the muffler, but the only way to minimize it possibly would be to have more space for the exhaust system. Larger diameter exhaust pipes and placing the muffler further away from the heat source in order to keep the temperature in the muffler below the ignition point of the unburned fuel.