Please help. I know this may have been covered before, but I need some help. My son's bike misses/sputters when accelerating, like coming out of a turn getting up to speed. If holding steady throttle it feels like it is surging. If open throttle completely it runs like it is supposed to. I recently went through the engine. New piston, valves and springs. It had hotcams stage 2 last year and it was ok. It started a few months ago before the engine work. I have double checked, tripple checked the timing and valve clearances. I have tried new jets and pilots, I cleaned the carb and installed a dynacraft jet kit per thier instructions, no change, so I put the factory jets and needle back in. I have swapped out the CDI and the coil. no change. When it is sputtering it also kinda pops out the exhaust, will also pop badly on decel. I'm really at a loss. I cant afford to take it to the dealer. Looking for some guidence. Thank You

 

Try the Earth mod. Worked for me.