Jetting Question

[Rob666]

I have a 90 yamaha phazer II and it has an old PSI aftermarket exhaust on it. I know that you have to go to a larger main jet, but how much? It has the stock (143.8) main jets in it and im wondering if anyone knows how many steps up I need to go? Is a 145 enough? I just put a fresh top end in it and would hate to melt it! Any help appreciated
thanks
rob666

 

[lightweight]

i had a aaen pipe on mine ran stock mains but richend my pilot jet. this was for 6000 feet. i would try at least 3 sizes with a new motor