Dear MXA,
My 2006 Kawasaki 250F backfires when I roll the throttle off. I've gone from the stock 40 pilot to a 45 and screwed in my fuel mixture screw. Should I try another richer pilot or is there something else you would suggest?
We would suggest turning the fuel screw in the opposite direction. By turning it in, you are negating the benefits of adding a larger pilot. Try a 42 pilot jet and turn the fuel screw out to richen the mixture (turning it in leans it).
If you have a question, send it to mxa@hi-torque.com