- Aug 14, 2001
Ok jetting guru's, heres the stats. 98 YZ400f, non mx used, woods only, 14/51 gearing, Stock head pipe,FMF power core2sa,stock jetting. I'm getting hesitation at WFO throttle when the engine gets near the rev limiter. Does this require just a main jet change, or the pilot jet as well? BTW 300+ sea level and in Michigan ( the weather can be 90+ one day and 50 the next ). Any Mich riders input especially wanted on what your experiences with jetting this beast!