Well my 03 cr125 with an 01 kx250 pwk is having a strange bog on the bottom end but its very odd. If I start off in first and the rpms are low and I go wot is will bog and almost die and sometimes sputter. Mid to top it runs excellent once the rpms are up. Now I know this sounds like a lean condition but Im gearing down to a 12/52 and heres my specs: 175 Main 45 Pilot NC3G #5 #8 slide AS 1 turn out I have the 05 airboot with six holes drilled in airbox, stock exhaust and motor. Is the 5.5 slide that important? Theyre around $50 and Im thinking of ordering one. Btw I just put a new cylinder, head and piston/rings in and compression is at 135lbs. I really like the bike but im puzzled at the moment because this bog is so severe yet sometimes it doesn't happen.