I have a 89 Quadzilla that i just restored from the ground up, this is my first 500 so i dont know alot about the motors! I installed a Paul Turner pipe and silencer a cool head and a 39 PWK carb with pre filter NO air box! It will not run on top end! i think the jetting is not right, i have tried everthing from 160 main jet to 180 main jet? Need help getting it jetted right?[img]i/expressions/face-icon-small-disgusted.gif[/img]

 

Call Duncan Racing. You essentially have their bolt-on kit. My experience is that they are a little stingy with info but, since you are using their pipe, they should be willing to help. Before I had my 500 ported I had the same set-up you have now. I don't remember what jetting I used back then and now I use a digital EGT to get the quad fine tuned (no more burn downs).

By the way, you aren't going to get large R's and great top end without porting. I had to short shift before to experience the power but, now that the 500 is ported, it pulls way harder up top with a small loss of low/midrange.