A few weeks ago I purchased an 06 KLX250S and I really want to thank this forum and all the guys who have taken the time to post all the very helpful information; thanks to everyone!
My DJ2206 kit should be here tomorrow and I have found & recieved a good deal on a 300 header and a plugless can. I need your opinions please. Most of the info I have gathered is to use a 128 main jet, clip 2nd or 3rd from top, slide lift hole drilled, and mixture screw 2.5 turns out. The DJ kit suggests the 132 for up to 3000 ft and the clip in the 4th from top groove; out of all the info I have read I do not think I have seen anyone use this setup. I really only want to remove the carb once. So what do you guys suggest?
I have no lid for the air box, aftermarket air filter, T-handle mixture screw, and I will be riding in the Foothills between 1168 to 3500 ft elevation; mostly in the lower elevation.
Thanks in advance!

 

my suggestion is 128, clip 3rd down, and I'll bet you'll still be a bit on the rich side. but review this.

https://www.kawasakiforums.com/forum...62/#post490779

 

Thanks for the reply! I had reviewed that spreadsheet before but there are only two guys listing 300 exhausts: a 351 at sea level and one who did not rejet. The air box lid was gone when I purchased the bike so I am pretty sure I need to rejet. Any issues with being a bit rich other than decrease in mpg?

 

My 2007 KLX250S ran perfectly with a 128 main. But then, that was with the lid on/snorkel removed. Didn't like the added intake noise with the airbox lid off.

 

the 300 exhaust is a little better than the stock can but is still pretty restrictive due to the header and overall design of the muffler so I wouldn't worry about the jetting being drastically different than a slip-on equipped 250 with otherwise the same mods and elevation. IMO

 

MPG, black soot on your fender and exhaust, and not the best performance. Lean conditions are generally easier to detect in the way the bike acts than are rich conditions by way of flat spots, hesitation, surging, etc. Per others, reading the plug doesn't do too much with today's fuels unless you are way off.

When I was running the 128 before big bore and open (HMF) exhaust at around 4500 ft with the lid on, the bike was so rich it burbled and would not rev out. Remove the lid and it went better, but still rich. The lid on/off is a fairly easy way to detect rich in my experience. Not all bikes, or riders, are the same. See if you can find a lid on ebay or something, if nothing other than helping to finer tune the bike. An exhaust gas analyzer is the better indicator if you really want to fine tune it.

Let us know how it turns out.

 

I understand what lean feels like on the bike; it is currently lean because it surges at certain rpm. Looks like most of the guys on the spreadsheet with the lid removed, slip-on can, and at 2000 elev are running a 124 main jet. I guess I will start with the 124 mj and see if it runs any different. If it still surges then I will go to the 128 mj. I'll be on the look out for a lid in the mean time.
Thanks everybody.

 

Like the dyno jet instructions suggest, duct tape can be used to restrict the airflow into the airbox for testing. The 2 brs pipe is loud enough that u forget a little airflow noise

 

man, decisions decisions.... I'm currently leaning (pardon the pun) towards a 124 main jet. If it proves to be too lean then I can try duct taping 2/3rds of the airbox and see if that increases richness enough. If still too lean then I will increase the main jet one size and repeat until I'm happy. I can't help but feel like I will be removing the carb more that just once.

Increased air box noise does not bother me, so lid (duct tape) or no lid makes no difference; performance is my goal.

I believe a 118 is the stock main jet size, so increasing to at least a 124 should not hurt; it just may not provide the best performance with the components I have.

Thanks again for all the replys guys!

 

You're not likely to nail it the first time. Don't stress about that.

I'm going to refer you to a great page here if you've not seen it already:
https://www.kawasakiforums.com/forum...q-links-30733/

go down and look for this: BigSky_KLX posts: Jet Conversion Chart for Keihin, DynoJet, Mikuni

Jet sizes between manufacturers are not the same. A 124 DJ is about the same size as a 132 Keihin. You're correct on the 118 Keihin stock main jet size.