Bike, 1974 Honda XL350 raced in Flattrack. 38mm Mikuni round slide carb, old school style. First kick from a cold engine, choke on. Usually never starts. No biggie. Second kick, the bike always backfires threw the carb. Will not start. If I turn off the choke before the second kick, bike almost always starts. I should drop one size on the pilot jet, right?