After hearing all the info you gave Mike McD on rejetting my quad is doing every thing wrong. I am almost positve it is running lean. When I am riding it it back fires every time I get off the throtle. I need to rejet it but am kinda broke.I wanted to know what size jets to go with and if you could give me the run down on the best product for the money and the right way to replace them. My quad has an aftermarket foam air filter, spark arrestor taken out, and I am not sure but it might be bored .30 over the kid i bought it from said that he wasnt sure but it might have been.