I'll try that when I have to rejet the carb, I'm currently waiting for my top end to be done,I'm having it ported and the head milled for more compression and the fly wheel lightenedCould be both. The forum just helped me with mine and it turned out to be a lean pilot jet for me. First do a leak test.then set your float height correctly. After that if it continues, turn your airscrew 1 1/2 turns out from seated and start turning in slowly to see if it goes away. If none of this helps you, try a larger pilot jet. Cost me $5. Search carb tuning.