I had a 95 KX100 big wheel for my son n daughter. Got it used and never did any work on it til the top end finally wore out after we had it for 5-6 years. The 97 n older had no power valve. I then got my daughter an 02 KX100 big wheel. It has a PV. I had the cyl milled to lower port timing to give it more low end-mid, still revs to the moon. Added a FWW and geared down one tooth in the rear. Added a kick stand and alum skid plate. It works great for her 5-02 100lb size. Both bikes could be lugged down and neither have ever fouled a plug with stock jetting. They just work great.