09 KLX250sf owner here 6000ish miles. Had the bike since new. Use it as my trail bike. I normally ride an FZ-09 on the road, so never went for the 351, though i was close to pulling the trigger once upon a time. But put the money towards the FZ instead.

So far the only mod i've done since was a FMF Q4 Slip on. Bike has been good to me, apart from being severely under-powered.

Anyway, thinking now is a good time to finally give the KLX250sf some loving, and give it the 351 it deserves. Never going to sell it, so may aswell upgrade it !

As much as i'd like to accompany the 351 kit with the pumper carb that bill blue sells, i can't really justify the extra $400 on top of the 351 ATM... Maybe at a later date.

Just running stock jets.

I'm in SW Florida so at sea level.

Not sure which jet kit i should be looking at to accompany the 351. Or is this a mistake and the pumper carb is almost a must if going with the 351 ?

Not ordered the 351 yet.. But will do within the next few weeks...

Any advice welcomed.

 

not sure about jetting for a cvk, but have you considered the tm36-68 pumper carb? Half the price of bills, and basically plug and play... Makes a huge difference in performance

 

Direct to your question: You have two choices with DynoJet kits - the 2206 or 2152.

The 2206 kit has a needle that is very different from the 2152 - measurements on it would indicate that it can keep low and midrange AFR's correct, for max power, with a very large main jet that allows for the upper and topend AFR's to also remain correct..

In case you didn't know, I have both bikes - 2012 KLX250S and 2007 KLX300R.. My 300 is running a 2206 kit with a DJ146 main jet, lidless, with stock exhaust (butt plug removed) , near sea level.. It'll pull engine only wheelies in 1st and 2nd with 3rd gear needing a tug on the handlebars..

 

A suggestion.. Before doing the BB kit, how bout bringing your existing engine up to its' full, current potential - which is about 22hp and 15.5 lb ft TRQ... Get the 2152 kit, call DynoJet and buy a DJ140 main jet ($2.00), install as per instructions for stage 2 but with the 140 main and the needle on 2nd notch down from the top. Remove the airbox lid..

Without the MCM (Marcelino Cam Mod) your max power will be in the upper end but it should be an "eye opener" for you.. If you like what you get, add the MCM for a little more everywhere..