What Jetting changes,
Air/fuel screw adjustment or
Needle adjustment :
Would I need for a 05 KFX 400 with a Yoshimura full exhaust, a K&N filter with no airbox lid at sea level ???
Thanks !!

Same question with Only a
Yoshimura (Slipon ?)

 

No set in stone adjustments for this atv or any other make.Depends on what you've done. Always see how it runs with stock jetting after what ever aftermarket parts or changes you make first.Take a high speed run,kill it quickly at speed and check plug color. Should be a tan to medium brown. If it's boggy or hesitates,spark plug is light or whitish in color,a jump in jetting is needed. It may take one size up or possibly more.This place can help on jets or a jet kit they offer.https://www.jetsrus.com/a_jet_kit_at..._2003-2006.htm