2003 KX 250 exhaust?

I've got a 2003 KX 250 and I'm looking around for some different exhaust. I need lower end power because I mostly ride tight tracks and some trails. What is the best pipe/silencer for this? I've heard the FMF Gnarly from a bunch of people. I've got a Pro Circuit Works and stock silencer on there now. Has anyone used a Bill's Pipes silencer before? Other than the pipe and a 12 tooth front sprocket the bike is stock.

Thanks in advance

I used a Gnarly on my 03. I tried the p/c works but it pretty much lost what little low end it had. A 04 head works well on the 03. Bumps compression up some and boosts the lowend.

Have you tried a stock pipe? The Works pipe completely eliminates any low end. Those bikes in stock form are supposed to have killer bottom end.

There is a power valve mod for that bike too.

The 03 does not have killer lowend. Its ok. They are a bit vacant on the bottom, then hit real hard and signs off somewhat early. The 04 has a much better spread of power than the 03. Between my fiance and I we've had 3 03s, 2 04s and a 07. One 03 was slightly used and was bought from a mx'r, it ran like a raped ape and I suspect that it had some port work done to it. Our other 2 were bought new. She ran a stock pipe and I ran a Gnarly. The stock works well but the Gnarly puts the power down low a bit better. Stock is definately better than a works P/C though. I have since sold my 03 but she kept hers as a back up bike. Over the years we fiddled with it to get it closer to what the 04 runs like. We swapped on a complete 04 top end and CDI but couldnt get it jetted right. There are slight differences in the cases, cylinder and crank between the 03 and 04, whether this had anything to do with the jetting I dont know. We ended up swapping the 03 top end back on with a 04 head and CDI. It ran very good untill the dreaded crank seal went on it. Thats a whole other issue! Its currently torn down getting new seals and a much needed rebuild. Should be together this weekend just in time for our memorial day weekend trip to WV. i also ran 13/51 and 52 gearing on mine. She also has a 04 and 07. She prefers the 04 over all of them. As do I.

Do you have to run race gas when you put the 04 head on the 03 cylinder? I have done the 04 ignition box and Gnarly pipe on mine already, it still doesn't have a ton of low end power but it is better than it used to be. It feels like a 125 when I swap back to the 03 ignition box now! The Gnarly also comes with a spacer for the power valve. It delays the opening of the power valve slightly and smooths the midrange hit some.

I was running a 50/50 mix of pump and Cam 2 110 but I have switched to straight 110. All my KXs, heck even my old CRs and YZs, have a tendency to ping under a heavy load especially when in super tight, technical woods or in a deep sand wash. So ive pretty much always used atleast some race gas. Ive done the spacer/shim mod on one of my older KX250s, a 90. Its actually been around for a long time. I didnt like it and took the shims out. It made it too smooth for my liking.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now