I have an 02 yz426. midway through the riding day it starts missing and backfiring at all throttle possitions. Suspecting a cloged jet, I dissasembled and cleaned the carb, changed the fuel in the tank and cleaned the spark plug and still had the same problem. At this point I'm thinking possible ignition problems. I've heard of computer failures causing the same conditions. A this point I'm looking for any ideas.