Hey all, this is my first post here. First let me thank everyone who has put so much time into these pages. What great information. So I have searched and searched these pages and gotten a lot of information, but I'm still struggling jetting my 1998 XR400 so I figured I would finally break down and post my problem. My bike was jetted perfectly for 7000 ft in Colorado. It was running 116 Needle in third position 52 Pilot 145 main. The snorkle is removed and it is running an FMF pipe. It started fairly well but once it was warm it started like a dream and ran like a top. I recently moved back down to sea level (350 to 500 ft. actually) and my bike (of course) didn't run well. I richened the mix by putting in a 162 main as the FMF and various other areas suggested. So anyway here is the issue. The bike now acts like it is running leaner than before. This is strange right? or am I just too much a jetting newbie? The bike would idle well after a lot of kicks and warm up but bogged at higher RPM's. After a few trips out I pulled the new plug and it was powder white which I understand is a sign of leanness as well. I just pulled the carb and there was a bit of grit in the pilot jet, but I assumed this would more effect off idle and not higher running. It wasn't much grit and like I said it was idling decently, not like before though. I just adjusted the valves and there was no real appreciable adjustment. Just a bit tighter on all four. The compression release is disconnected and the actuator wired back so it cannot engage. I pulled the valve cover off and everythign seems to be in good working order. I looked over the shop manual and it does not say how to adjust the timing. It just states to check the timing and assure it is right, so I'm not sure what to do there. Is it just right or you're replacing ignition parts? At any rate, any advice anyone has would be great. The thing won't even start now. I have not had a chance to give it a kick to see if it does any better with the pilot cleaned and the valves adjusted. Could this all have just been caused by a dirty pilot jet? This is the Keihin carb (I'm not sure if there is a variation there or if all XR's in 98 ran this carb.