Motorcycle Repair: 1996 rm125 big bore kit 135cc, big bore kit, riding my bike

Question
i was riding my bike when it died and now it wont start.it is getting fire to the plug and has gas.i have changed the plug and cleaned the carb. it is backfiring thru exs. when tring to kick start it.

Answer
Bo,Check the compression if you can. It should be around 90 lbs with the throttle wide open letting in the most air. Some of these models (modified) have aftermarket reeds,check to see if it has sucked in a reed petal,this would be like having a valve out keeping it from running.