jetting kx100 for trail riding
lean out the jetting on the bike and it will not foul plugs, and it will run better and stronger. My lady loves her KX100, yours will too- after you get the jetting sorted out. I put quite a few aftermarket parts on her bike to tailor it to her needs; some of which affect jetting. I had to lean out the main/pilot/clip and use a BR9 plug. That little bike can rip if she wants it to, yet still has manners. Start with the main jet and work your way through it.