Here is my set up. 13t front sprocket, KDX snorkle, #40 pilot jet, #125 main jet, fuel screw two full turns out, N1TC needle with collar on first notch, exhaust drilled 1/2" through first two baffles. Elevation here varies between 600 and 1600 ft.

I havent drilled the slide yet (didnt have the right bit when I did the rest) and I am about to put in a uni filter and Iridum plug.

I dont seem to get much use of the RPMs above 7000. I have been considering going with a dual snorkle set up and maybe using a hole saw to open up the exhaust. I dont want to pay for an aftermarket pipe.

I have read that some think the real restriction is in the header, if so is the extra cutting on the exhaust going to deliver any real gains?

Any suggestions?

Thanks

 

I don't think you'd get much real gain with the stock pipe. I'd consider a slip on, or also there are some lads that have completely gutted the stock muffler. What happens at 7000rpm anyway?

 

I also drilled out the air box outlet

 

It just really flattens out. I feel like the throttle response should be a little better across the whole rpm range, but over about 6000 it doesnt do much at all.

 

what's the spark plug look like?

I have compared the two, and there is a huge difference between a slip-on and drilling the aftermarket exhaust. Hunt down a stock klx header and exhaust, or check fleabay for a used klx300 system. Of course, an HMF would only set you back about $220.

 

ac, I know it is counter intuitive to think that the needle setting will affect performance at 6K rpms + it's supposed to be the main jet range, but one time when I was trying different man jets I put the washer on the wrong side of the clip for the needle. My performance was just like you are describing. Try the second and/or third clip setting for the needle.

PSyou can adjust the needle without removing the carb whichis aPITA, just remove the cover and pull the diaphram. Good Luck.

 

I would go back in to the carb and drill the slide out, and while your in there I would also raise the needle to the second slot. I don't think anyone on here is running the first slot. The 125 might be a little big with the stock exhaust, even drilled. Then I would take the header off of the bike and inspect the end and see if there is a big glob of weld inside of it. If there is it should be ground out to get some more flow through the pipe. There are a lot of people running the stock header with good results. I don't think that there is a flow problem(after the weld glob has been removed) with the stock header with 250cc displacement. Are you de-smogged yet. If not it might be something to think about.

 

Just remeber though after about 8 grand power will flaten out no amount of jetting fiddling will help timing and canshaft design is the limiting factor.

 

I dunno man, I seem to be able to pull up to 9 then it flattens. Also go the muzzy exhaust though. I'd also make sure the needles set up right, and try the 2nd clip (from the top flat part)

 

It pulls but really starts to flatten out though.