I've got a very rich running yz 85(black or fouled plugs every ride.)I've tried many different ratios of premix-all with the same result.Currently I have the clip in the top groove of the needle and the fuel screw 1 1/2 turns out which seems better.The main jet is a 138 which seems a little small to me. Should I go bigger or smaller to lean it out?I'm a lttle worried the clip is in the top groove. My son rides pretty hard so I know its not that. Please help.