recently I have picked up a 1999 YZ400F. I took it out to the track one weekend and it ran good, idled fine and had crazy power. Then it sat for a few days and when I tried starting it again, nothing happened. So my first guess was maybe the carb, So I took it off and examined it, opened the throttle and noticed that it wasn't squirting gas. I took it apart and turned out my accelerator pump diaphragm was shot. So I replaced it and it squirted gas perfectly every time I opened the throttle. But when I put the carb back onto the bike and cranked it a few times, I still didn't budge. At first it felt like it wanted to start but then after numerous kicks it just didn't want start. I checked the spark and it was there. The compression was also there. And the accelerator pump was now good as new. My pilot screw is set to standard (1 3/8) turned out, got a brand new spark plug, great compression and fresh gas.
Anyone have this same issue. PLEASE any advice would be greatly appreciated!!!