just got a 2009 klx250s with a fmf q4 slip on and the airbox snorkel removed. previous owner says the jetting was not changed. what should my jetting be for this combination.bike hesitates when opening the throttle quickly. thanks.

 

This will give some ideas

 

Same set up as mine. Look at my sig below for my jetting details. Altitude will affect your results. I'm at 750 ft abouve sea level.
Dan

 

Yea check out peoples signatures..itll tell you all you need to know

 

im at 1300 ft elevation. if i put in the 128main and 40 pilot , can i stay with the stock needle and not shim it? thanks.just trying to get rid of the hesitation when i accelerate. i imagine that turning out the air screw will probably also help with this hesitation?

 

Shim the needle, it will help with the surge. It's a 'fuel screw,' and yes turning it out will help to a lesser effect than shimming the needle (raising it.)