I just put a FMF Powercore 4 exhaust on my 2009klx250s. I talked to FMF about rejetting, and they recommended 1 to 2 up on the main and 1 up on the pilot. What is stock?

 

The stock is 118 main and 35 pilot, in kawi jets, on my '06. I think your '09 is the same, but I'm not positive.

If you're rejetting, highly consider going the DynoJet route. The needle in the DynoJet kit is a huge improvement over stock. The kit will also come with a range of main jets to try. Don't confuse the kawi jet size with the dynojet size - they are different. Find a post from a few days ago with a comparison chart. I put on an HMF muffler, went to 128 main, then back down to 124 main and its good. I also bumped the pilot from 35 to 38, and back down to 35 (these are kawi pilots - the dynojet kit doesn't include pilots). It was too rich with the larger jets, but I did turn out the pilot jet mixture screw to 2 turns from the 1 turn at stock. It may depend on your elevation; I'm at 2500 ft and up.

And while you're in the carb, if your bike is hard to start cold like most, think about drilling the enrichment jet (choke) to 0.018". There's several posts here on how to do that one, and it works like magic.

 

I can confirm that the factory pilot on my 2009 non-cal model is stamped with a 35.

Looking at folks on this site with even more open exhausts than the FMF, I wouldn't touch that pilot.

 

Just put my crab back on the bike after drilling out that little sucker. Started right up, but the air temp is 55F. We'll see how it does in the morning at 32F.

I'm gonna hold off on other jet changes until bigger gas tanks are available for the '09+ bikes. Making it run any richer before then with 2.0 gal of fuel is just something I'm not willing to do.

EDIT: Bike started this morning at 33 degrees. NO ISSUES!

 

Sounds like another successful drill job

 

No trouble at all, although the tiny size of that drill bit gave me nightmares until I actually did it. In another life, I drilled a few hundred thousand holes in circuit boards using a #64 bit and those used to break regularly -- #77 scared the crap out of me.

Never could find my pin vise so I used my Dremel. The hard part of the job is getting the carb off the bike.

 

I am not willing to say that proper stoich jetting will result in higher fuel consumption. The theory is that when you put the proper jets in there that you will be able to adjust the idle down. At speed, you will need less of the proper mix per mile. Maybe mpg will actually go up!

 

Let us know where you're from? Some models in other countries have a different carb' set up among other essential items.

AUS bikes come with a #132 main and a #35 pilot from the factory but we also get a different CDI among other parts.

 

FWIW I get 300+ KM per tank on my AUS 07 KLX250RH7. Kawa jetted #138 main and #38 pilot with Twin Air filter and Two Bros M7 pipe. Gearing is lowered too at 13/45, but that's the key . I can run the bike in the 6th gear quite a lot (overdrive on the 07 and earlier bikes. 09 gets a shorter 6th gear,) and that seems to give me very good fuel economy, considering I'm riding 95% off road mixed terrain.

 

Well, I uploaded my notes on the DJ kit for my 250S. My next step is to pull the carb and adjust the float. Does anyone have link or notes on adjusting the float?
I'll put the 38 pilot in, and the quick adjust mixture screw.
I'm running with the air box cover off.
Any feedback would be appreciated.