2006 KLX250

[Dr Psyko]

My KLX250 needs to be upgraded, thinking about trailering out to Dakotas this year. It's still stock, and the carb seems too lean even as stock, very restrictive exhaust. I want to add a slip-on exhaust, and open the airbox, rejet the carb. Any experience out there with what works? Thanks!

[Hank]

Can't speak for the KLX in particular, but I've added JD jet kits to 3 or 4 different bikes now and they have worked great with slip ons.    They are a bit spendy for what you get (a few jets worth a few bucks each), but if you value your time the grief and fiddling around they save is worth it.

I've also used Dynojet and Factory Pro kits but so far JD has been the best "out of the box".

[woodsrider 53 RCSD]

Hello, DR.Psyko  I purchased a new 2012 KLX 250 in 2012 I did not ride it very much in the stock version but here is what I did to mine FMF Q4 slip on muffler and a FMF Megabomb header.With a dyno jet kit.For the air box I purchased a KDX 200 snorkel it fit just like the stock one there are pics on the internet somewhere you can see the difference I did not want to remove my air  box lid. I  think I paid 40  dollars for this so  removing the lid would be cheaper and it would run better, I am going leave mine with the lid and snorkel on. I cant remember what aftermarket air filter i baught  but if to buy another one it would be a twin air. And I installed a 13 tooth counter shaft sprocket. I wish I could say I installed the jet kit and tuned it in but I took it to to the shop for this, for me that was money well spent it runs great for me this way. Hope this helps you out. 

[tannerc]

Ziggy has a lot experience in the KLX department too. hit him up with a PM

[ZIGGY]

Woodsrider covered all the basic derestrictions the klx has to offer. You can get by without the header upgrade just fine imho. (Although I finally bit the bullet this fall too.) I have the FMF Q4 as well and it is probably the quietest aftermarket can available but is still plenty loud and beats the snot out of the stocker you can plug with your pinkey.
There are alot of additional things that you can do with minimal results. (remove smog stuff, backfire screen,  crankcase breather mods, etc.) Best bang for buck is probably a big bore kit, but the bike will definitely wake up with the exhaust/intake mods with the dynojet kit and it is a good starting or ending point. None were very difficult to do. Getting the carb out is probably the hardest thing to do. (Seat and tank removal, a few cuss words, some elbow grease and it's done.
Here is a link to the kawasakiforms that has alot of good information. http://www.kawasakiforums.com/forum/klx-250s-71/klx250s-faq-links-30733/. There are walkthroughs on just about everything you can possibly do to these  bikes on this site as well. Here is the main kawi page. http://www.kawasakiforums.com/forum/klx-250s-71/
Google searchs with topic and kawasakiforums works good for specifics
and one for the adv site. http://advrider.com/forums/showthread.php?t=107591
Any questions, feel free to ask.

[Dr Psyko]

Thanks guys, great info! I've used the dyno-jet kits in the past, maybe will try the JD this time for jollies. I've usually used K&N filters, any plus or minus there? I needed to clean the filters 2 years ago out in SD, and I remember they seemed to clog faster than other makes, maybe I'm just not used to that much dust. When we raced dirt track karts, always used a K&N, but with a nylon pre-filter. Maybe need one of those for the SD dust.

[Hank]

I've read numerous places that K&Ns will let fine dust through in dirt bike applications.

I like Notoil or twinair myself.

[ZIGGY]

Some swear by the k&n filters, but I don't think I'd wanna use one in as dusty of conditions as the hills. The sock might help. I've been using the pre oiled no toil lately, they are reusable with the no toil cleaner and oil, and seem to be holding up well. Some people still run the stock filter. but I don't think they have as much airflow. UNI and twin air are good bets too.
I haven't seen much info on the JD kits. Most are using the dynojet. They come with a decently aggressive needle and all the jets needed even if you upgrade to a bigbore later. There are no pilot jets included, but not too many people have the need to upsize it. I didn't anyways.

[Hank]

If the KLX experts recommend dynojet, I'd stick with that.    JD has been great in my WRs and KTMs, but I can't speak for the KLX.

[tannerc]

I've read numerous places that K&Ns will let fine dust through in dirt bike applications.

I like Notoil or twinair myself.

Yup that's true.  There are a few tests proving this on the " bobs the oil guy" site.  I wouldn't put a k & n in any dirt/ dual purposes bike.