Hello Kawasaki friends,

So I just traded my 2007 Honda CRF250r for a 2009 Kawasaki KLX250s and I'm pretty excited.  I'm new to Kawis and dualsports all together, but the bike seems to be in pretty good shape.  In general I was seriously underwhelmed by the power of the bike compared to MX bikes I've ridden in the past.  Over the winter I'd like to get the bike stripped down to get this thing pumping out some more power.  My plan is to open up the airbox, rejet the carb, and drop the front sprocket down to a 13t to start.  I'm in the process of putting money aside to get the 351 kit and an aftermarket exhaust.  The bike is about to hit 13k miles and I'm hoping the new top end and cylinder with give the bike a lot more life.  I know these motors are supposed to be bullet proof, but I'm curious if you guys think I should do any other work to the motor because it has such high miles.  


I found this jet kit online after reading a few other threads about these modifications.. Anyone have any opinions on whether or not this is a good kit?


Lastly, the previous owner decided to paint some of the plastics with some low quality brown paint.  No idea what kind of paint it is.. does anyone have any ideas on how to get it off the plastics or do you think my best bet is to just buy a new set.  


Thanks in advance for the help!





Hi, you want the dynojet 2152 kit, you can get it on amazon, the one you show in the picture (unless generic) looks to be for the KLX 300. You'll get the most hp with the airbox lid removed. I bought the snorkel for the KDX 200/220, it is a perfect snap in fit and flows twice as much air as the KLX snorkel, it goes down below the filter too for protection from water if that is a concern. You will definitely want that 2152 jet kit if you remove the lid or use the KDX 200 air box snorkel, the bike is jetted way lean to start with and flowing more air only increases the lean condition. You may want to join kawasakiforums.com. Lots of smart KLX owners on there and very helpful community. My settings at 2,300 ft above sea level.

'14 250S, 13/48, FSW Pipe and Silencer, DynoJet 128 main, DJ needle 3rd slot 2 shims, air 2 1/2. IMS tank/pegs. Renthal RC bars, UFO '06 KX Rear Fender, Yoshimura tailight.


Arghhh... that tan paint makes me sad...    if you are going to run it off-road, just keep them and beat the snot out of them.  Replacements are $70 - $100/side before shipping and rare on ebay. 

Dropping to a 13 CS sprocket makes a nice difference for cheap.   I ran 13/42 for a bit, but I like to ride tight singletrack so I'm now running 14/49 (w/110 link chain).  It keeps the rpm in a better range at lower speeds... but not very road friendly.

I believe I also used the 2152 kit.  You'll want to use their settings for stage 1 at first, then later bump up to stage 2 when you open up the exhaust.  I'm currently running an FMF Q4 with PB header, lidless airbox, DJ144 main, 40 pilot, needle on 1st slot, 2 1/4 turns out, at about 400ft above sea level.   I also ran the stage 2 settings of 128 main and 3rd slot on the needle and no snorkel...  both setups run great at near sea level.

If you want more snap like an mx bike, you might want to look into a pumper carb...   I'm old and a dirt noob, so I don't mind the slight lag of the CV carb... it gives me a little buffer for when I do something stupid.

351 kit is on my short list... but I still can't outride the stock 250 so it may be a while before I drop the $$

Edited by Abramsgunner

Check out partszilla for replacement plastic for the 09 n later klx250s. Check different years pricing as it does vary. I paid for black oem plastic to replace the red, somehow the bike became 10-15% faster over night! Side panels were cheap! Left $26.72 right 26.32 and I have a full set of red oem plastic I’m not needing anymore since the black looks so neato bandito!

I went with kit 2206 as the vent hole on the bottom of the slide gets drilled out to allow faster lift of the slide similar to the lighter strength replacement spring included in kit 2152. Plus the taper of the needles is different, the 2206 needles profile more resembles the needle in the fcr35 pumper carb I eventually went to for better throttle response, abit more power too esp w bills 350 bb kit. I also went w a 40 pilot and the largest dynojet main jet provided, clip in the middle, 2 bros can & pwrbmb header, uni air filter, no air box lid, reed block off plate installed, crankcase vent mod n blocked off the air box thingy, mysteriously emissions stuff fell off one day. In my quest for max hp I even followed fsw suggestion of grinding out the weld on the inside of the header flange on both the oem and fmf poeerbomb headers, matching exhaust port outlet size with the header flange id (every little bit of efficiency helps performance!) DMC eBay footpegs, edge taillight, Scott’s stabilizer, renthal bars, cycra handguards, ims 3.0 tank, 13-14x45 gearing renthal sprockets rk x ring chain, 3/4” fork spacer... 

Edited by 5Rs

Auto motive paint stripper from auto zone or kragen should soften up your paint job quickly, just remember to use rubber gloves n eye protection. Even brake fluid will work also it’ll loosen it up to make removal easy

I bought my 09, a few years ago. I traded down from a DRZ400s that was all hopped up and a real handfull!

This KLX is perfect for me! I went to the 14/47, Q4, jet kit, de-snorkel, Ascerbis hand protectors, and lots of gas. Gas is great for improving your bike's performance. Fifty or so tanks and the bike works great. 

I mostly ride in upper Georgia mountains with Adventure guys. They laff at my little bike until it gets muddy or rocky. Then I zoom by and giggle! 

My goal was to ride it until I couldn't go any faster on it. That happened right before Christmas at Durhamtown. I ran with some experienced riders on YZF250's and they were sliding, revving, jumping, and , I could keep up. End of the day, I took the lead and revved the nuts out of it! I stayed in front, slipped around a bit, but saved it, and kept it going. Big laughs at the end of the day.

Now I'm wondering:

The 331cc is on my short list, but I'd rather upgrade the rear shock first. I'm 180lbs, and see that RaceTech has a stronger spring, but is there a replacement shock I can use?

thanks, and buy more gas!!

Your gonna like the big bore performance. Carb mods plus a good complete exhaust system will have you gapping your buddies even quicker! 

I got away with just using a pvc pipe 3/4" spacer to firm up the forks, but I'm 20# lighter.... Heard good things about the springs and the gold valves - an upgrade to your shock n fork internals. I forgot where I seen it but some guy got a shock from a mx bike, the owner commented he needed to dimple the frame to get additional clearance for it to work but it looked like it would work.                                                                        

Before you do anything try some octane booster.
Sometimes they call it power booster.
They sell it at Walmart in a can in the automotive section.
That way you'll know if you can handle the power that your big bore will make.
If you like the power go ahead with the Big Bore Kit.
Just read the directions on the can and don't use too much.
We tried some in a small Honda we used too much and it blew the head.

I have no personal experience with these guys but am thinking about trying their springs and valves.

You could be the guinea pig and report back!

Cogent Dynamics out of North Carolina


They have a good rep, and I would consider them top-shelf.  I ran one of their shocks on a '05 KLR650, it was a nice upgrade and too pretty to be on a KLR....lol

On 1/3/2018 at 9:03 AM, arthur6 said:

Before you do anything try some octane booster.
Sometimes they call it power booster.
They sell it at Walmart in a can in the automotive section.
That way you'll know if you can handle the power that your big bore will make.
If you like the power go ahead with the Big Bore Kit.
Just read the directions on the can and don't use too much.
We tried some in a small Honda we used too much and it blew the head.

I been looking for that RedBull octane booster, I hurd it wuz the shit!

And maybe lighten my frame by drilling some doornob holes in it.That metal is soft, should cut weight real ez. And I been calling around for helium in my tires. I'll do anything to keep this baby alive!!



Don't waste money on octane booster, it doesn't work very well and even if you ran 110 octane it wouldn't add power at all, the only thing high octane does is prevent detonation.

Raising the compression would help performance when running hi octane fuels. Otherwise it's a waste of money. 

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