2000 CR 250 jetting

[Green=Go]

Just put a new top end in the bike, standard bore. I am running a new fmf fatty, and added boysen dual stage reeds. I didn't change any jetting. Runs like hell on top end, but lost everything on bottom. Spark plug seems to be perfect. Anybody else running a similar combo, I'd like to hear what jets you have. FMF recommends staying rich on the main while boysen says to lean it down on the main. And then fmf says to lean the pilot, and boysen pretty much stays stock. I've got the specs from both, but just trying to get a good base line to start. Thanks

 

[whenfoxforks-ruled]

You have way too much base already. Start with what the book says, and jet your own engine. My 2000 has a Keihn on it. The most important factor is your premix ratio. Here again, mine is 20:1. Do you really want to know my jets and needle sizes? Keep it simple, change 1 circuit at a time, make big changes if you are unsure/can not tell lean or fat, start with the air screw/pilot. And most importantly, read: http://www.dirtrider.net/forums3/showthread.php?t=42618