1........checked valves
2....changed fuel filter
3..changed spark plugs
4...changed co2 cartridge
5.removed carbon filter
all above no help
6.........changed spark plug caps..............runs like a neww bike now ......hope this helps someone ....i spent alot of time and alot of frustration before finally got it corrected ..............also had alot of advice on what to do without any good results ....