[krisrtch]

Hello all,
Well I own a 2006 CR250 and i rejetted it after putting on a FMF SST pipe. Well the temp has dropped to about 40 to 50 for my final race Sat night. It has been about 70-80 on race nights. and my jetting was pretty spot on. I was wondering now that the temp has dropped what would be best coarse of action. When I jetted it i went down one size on both main and pilot. and air screw 1.5 turns out. Would I be able to get away with turning the air screw in a half turn Or would be putting the stock jet be the best way to go. Any help would be greatly appreciated.
PS i'm at 20' above sea level

[mustang]

how is it running in the cooler weather with your current s/u ? any engine likes bigger main jet in colder weather .

[krisrtch]

It was running a weird last night just didn't wanna idle worth a darn. Seemed a little off when I got on it. Took a little longer than normal to get up on the pipe.

[krisrtch]

WEll I got home tonight and pulled the plug out and she looked great nice and brown. Guess I go tthe jetting on for cold weather not hot. I 'll try the stock jets when it warms up again and see what the plugs look like.

[Mikey350D]

Do you use race gas??
I mix 50/50 pump/race (CR125)
I have had huge jetting problems in the winter when the pump gas formula changes.
Not sure what they do; add ethynol?
50/50 mix insures fuel is consistant

[krisrtch]

Nope all I run is 91 Octane pump gas. I can't afford 9 bucks a gallon for race gas. i check my plug and the plug is a nice golden brown and she has been running like a champ.