I cut out the restriction plate out of my exhast end cap, and added a k&n air filter. I want to take my air box lid off so im getting a outerwears. How much biggger should i rejet to. By the way this is on a kfx 400. Thanks.

 

1 or 2 sizes up from stock should be enough

 

never rejet with out checking your plug first whats the point? put a NEW plug in let it run for a bit and check it should be dark tan if not white is lean black carbon is rich adjust accordingly then take it for a ride and check again also there are many aspects to jetting correctly diffrent jets control diffrent throttle positions read up a bit before you try and tackle this correct jetting is where the best performance lies. check dirtwheels online site. for maintenece tips and then hot horsepower tips this should give you a lil better idea of what jets do what. http://www.dirtwheelsmag.com


hope this helps