2009 KLX250SF. Worked on the bike a bit the other day. Removed the stock airbox and replaced it with a UNIfilter OEF, and moved the battery and overflow can under the seat. I have an FMF slip-on right now and had already jetted it. It ran good last time I rode it but I just had it in the shop to replace the stator and the mechanic said it wouldn't start without the choke once he got it running. It sat for about a month at the shop so I don't know what happened. He suggested I rejet the bike with that new filter. How much more fuel should I give this thing? I used the Stage 2 Dynojet kit last time.. Any suggestions?

 

I don't know if this is your starting issue in this case, but when you remove the airbox on a CV carbed bike, sometimes they can do some odd things. The CV carb generally likes a nice, undisturbed, "dead-air" space to draw from. The vacuum slide is very sensitive to intake disturbances. Usually it's manifested more while the bike is moving and the air around the clamp-on filter gets disturbed. I saw this on lots of multicylinder bikes using clamp-on filters and CV carbs back in the 70's and 80's when that was popular to use external K&N's and Uni's.

On your jetting, I'd agree that removing the airbox is probaby going to require richer jetting, but you're in new territory there on any exact jetting specs. You'll probably have to experiment with the pilot, needle position, and main jet.