When mine was a 250 it ran great on the 128DJ, but I had the airbox top open, and a full Muzzy exhaust. The stock header pipe is a small sucker, and I never rode mine with anything but the Muzzy.

 

When I got my 09 KLX it had a jet kit, FMF Q-4 with power bomb and air box lid off and ran pert good except for the lazy throttle. I bought the Bill Blue carb and thought I was in the hi~cotton. The first thing I did was change the fuel screw to the one on the right in picture. I had one in a 450 Yamaha YFZ and it ran good so i figured what the. After a while on some logging roads trying to keep up some what with a orange bike I felt the engine flattening out around 6,500+-. I thought I was running out of fuel so went on Res. and it seemed to go away? Called BB and he said to check for a pinched fuel line,[not]. I took out the red fuel screw and put in the one BB sent and no more problem. I'm now breaking in the BB 351 with same carb and pipe.

Look at the taper between the two. One on left is the same taper as the T handled one BB sent.

Idle to 1/4th is pilot 1/4 to 3/4 is needle 3/4 to WFO is main[or so I have been told.

 

Thanks for all the info guys, I will try changing the main jet and see if it helps any...I will get back to ya and let ya know what happens.

 

You've got to be sure to sift through this advice and consider that some of these folks don't even have the same carb as you, totally different operation.

Why do you have a 38 pilot? You should have a 35 and the fuel screw three turns out. The pilot jet circuit is much more important on a CV carb than it is on a slide carb such as the one bill blue sells. Third groove is the proper needle groove so leave that alone.

Go back to your jet kit, bought from experts, and follow the directions.

 

Well I got the 38 pilot at the same time I ordered the jet kit because of information I was reading on here. Seemed allot of people were talking about opening up the klx and on more than one occasion people said they ordered the 38. Not knowing a whole lot about the carb I just went ahead and ordered it too. Bike seemed to run good after putting it in and since the heistation was present before and after I decided it probably had nothing to do with the issue. I realize people have different carbs and setups for different altitudes but having for the most part a stock motor and being at sea level, I figured it shouldn't be that hard to figure out with so many people on here.

 

Your condition doesn't sound like the pilot jet. I run a 35 in my KLX with a 300 jug and full Muzzy, but even with yours at a 38, it shouldn't cause your issue. I'd still try the 128.

 

Sounds good will try it out

 

Reading some of the above I went out to see what was in my stock carb. Dynojet stage 2. 38 Pilot needle on 3rd[from bottom] and a 120 main? The paper work said 120 for above 6,000', not what I would have put in it as it shows a 128 up to 3,000. fuel screw was at 3 turns out had I known that and was going to run the stock carb I would have went up to a 40 pilot and stayed with the 1.5 to 2.5 out on the fuel screw.

A friend with the same bike[all stock] wanted to get off the choke[yea I know it is a inrichen system] a bit quicker. We put the 38 pilot and needle out of my
stock carb and went with 1 3/4 out on the fuel screw. It seems to work fine on his bike.

I wasn't trying to tell you how to set up your bike just relating some of the sh I went through. All the bike carbs I have worked with over the last 53 years I have been messing around this two wheeled sh move air through a big hole and suck fuel through some smaller ones. How you open up the big hole don't make much difference. rag away

 

Maybe it is important to also specify which DJ kit we are using. The needles are very different between the 2009+ kit and the klx300 kit. Maybe that difference changes how much fuel the main jet feeds. Just a thought.

 

Now that's a good point.