My friend and I were discussing jetting on our quads the other day, he has a stock '06yfz450 and was told that his runs lean from the factory, which causes rough running at lower rpms, also a glowing red header pipe. He said that re-jetting (fatter) his quad resulted in smoother low rpm, and the header pipe quit glowing along with more power... Ive noticed this on mine and was wondering if anyone has done any research on the stock jetting. Does it need to be re-jetted?

 

Depends on your altitude, air box/air filter, and if you have any exhaust improvements. If you are close to sea level you might be a touch lean.

 

Im in northern ky, about 800 or little more above sea level. Would bigger jets help with low throttle stumble and get rid of red header pipes?

 

Sounds lean off the bottom but doesn't mean you need bigger main jets.....you can go to a bigger pilot jet and move your needle clip down a notch or two for a start, that affects your part throttle mixture.

 

So I do have notches on the needles on my raptor? You said bigger pilot jet, dont I have to do it to both carbs? What is the stock sizing for the mains/pilots? Thanks in advance for all my questions[img]i/expressions/face-icon-small-smile.gif[/img] Going from drag racing cars fooling with carbs on small blocks is completely different from small engines and Im still learning...