Aright I am back agean and I have put a yoshimura rs3 slip on,K&N and jeted my 2001 raptor 660 and it runs like crap. I have the jetting at 157.2/162.5 and the plug is burning nice and tan so im amost sure its not the jetting. Any way down low its running good but when you open it up and try to get the RPM above 5000 then all it will do it pop and back fire. Yes the crab boots are on good. This thing is running way worse than stock. Also Im not sure if this is the problem but when I was playing with the needle I lost the small spring that goes in the float.(ya I know Im a dumba$$) I Then went to a hard ware store and bought a spring that would fit in there. I would buy them from the dealer but they want to sell a needle set with the spring and entire needle and they want 55$ a set and I lost bouth springs and dont want to pay 100 dollors for 2 little springs that cost like 10 cents. I dont know if this is the problem or not. I dont know if that spring is just there to hold the needle down or if it pushes up to let fuel in and has to be a certan compresion or somthing. I would apreashate any help.