Hi, im really pulling my hair out with this kx now, i was wondering if anyone could assist me and maybe help diagnose the problem. Kx 250 1992 all gears work fine except 4th it feels as if teeth are missing. So its giving the feeling as if the clutch was coming on and off but no drive to the back wheels high or low revs (only 4th gear) Ive replaced gear shaft and cogs but keep in mind when i split my engine my gearbox was fine. but i still replaced with the box i bought i didnt replace drum or forks. when i assembled the bike everything was fine for the first 20 mins/3miles. Please help any info as to where i should be looking at next? maybe forks and selector barrel? as the clutch is healthy and recently replaced. If anymore info is required please just ask as i really wanna be out on this for the summer Thanks scott.