KLX250S Stalling/Computer Resets/Won't Start

Hey Thumpers,

So, I've read thru every single thread I could find that could possibly contain an answer to my issue, both here and over at Kawasaki Forums... so I/m posting it as a new topic!

My '09KLX250S (which many of you have helped me out with before) is now acting up in a very strange way that it never has before. For the past two months or so, the bike has been mainly sitting in my shed for the winter season, but I've been firing it up here and there and done a few short rides to make sure it stays in shape. Back a few months ago, I dropped the bike real hard on the Slickrock out in Moab, and ended up busting one of the notorious shift star pins. Other than being a pain to wait for the parts and ripping everything apart, and finding a new shift lever, it really wasn't too big of a deal... she's shifting better now than ever before, much crisper and more distinct shifts (I now have the newer start gear design).

When I was out on a ride (on the road) about a month ago, out of nowhere at all, the bike began to sputter under throttle (EXACTLY the same feeling as when throttling the bike too much when it's still warming up from cold). I instinctively began to baby the throttle and keep it running, but slowly it just sputtered to a stop... AND the computer flashed off and on and reset at the same time. My immediate reaction was that the battery was acting up. I was able to get it started again, but shortly down the road it stalled again in the exact same way (computer reset again), and I was never able to get it started again (not even with a roll start). For the past couple weeks, out of frustration at having yet another issue, I stuck to snowboarding and let the bike sit in the shed with the battery trickle charging, half hoping it would mysteriously heal itself!

So, fast forward to this past weekend... after doing every test I could on the battery with a mutimeter (non-conclusive, as everything read correct during a load test) - I took it to O'Reilly and Advance Auto to have them test it... O'Reilly guy said it was fried, and the Advance guy said it was fine (but didn't seem too confident). I tried starting the bike straight off the original battery, jumped it off of a car battery (with my battery removed), and also jumped it from a plug-in jumper box. I was never able to get it started again with just the battery itself, but when plugged into the car battery or jump box, I could get it to start about 75% of the time... but after idling for awhile she would just poop out slowly again... the computer reset most of the time, but not EVERY time! So I just decided to pick up a Bike Master replacement gel battery and try it out. This afternoon I installed the new battery, said a prayer, and fired her right up! it ran for a few seconds, I killed it, restarted it, fired it back up, and figured I was good to go... but as soon as I gave it the SLIGHTEST bit of throttle it died out again just like it had been. However, the computer has never reset so far when stalling with the new battery installed.

As I said, my initial impression was that it was a battery issue right off the bat, but I was/am also very suspicious of there maybe being a loose ground or electrical connection somewhere. I still haven't begun to gut the bike and check out all of that stuff, but that's what I'm about to start here in a minute. I'd really like to know if anyone can help me with suggestions on where to start though! Electrical weirdness (computer reset, etc) notwithstanding, I could also see it being a carb issue... but that makes no sense in terms of explaining the electrical crap. It also doesn't seem to me that it would be the magneto or anything like that, given the strange and varying symptoms. The fact that the computer only resets some of the times when it stalls seems to me to support the fact that it could be a loose connection somewhere.

Up until now, my bike has NEVER failed to start up right away, never stalled, and it has always run totally flawlessly.

Anyone, help??


Jon W.

I'm still struggling here... absolutely no progress whatsoever in identifying a possible cause. At this point I've run every single electrical and mechanical test that I can possibly think of, including all of the tests in the service manual and others that folks have suggested. HEEEELP!

How about checking for spark when it won't start? Use one of those cheap neon lamp goodies that go between the spark plug and the plug wire.

Ride on


sounds like it could be electric... does it run fine after you get it started???

i'm gonna go out on a limb here and say it is a combination of 2 things, but its just a guess...

bad battery AND a dirty pilot jet...

symptoms scream pilot jet (bogging off idle) and been through it before...

brand new 2012 klx250s off the showroom floor for my girlfriend, she rode it about 500 miles and then went on a road trip...

bike sat for 5-6 weeks on a battery tender...

when i tried starting it, starter cranked healthy but it wouldn't run... if it did it choked out quickly...

brought it to the dealer for initial 600 mile inspection and oil change... after getting raped on a $150 visual inspection and oil/filter change (initially told they would check valves which they did not do, only reason i brought it in... after an additional almost $200 to "clean carb and pilot jet" (grab ankles here) the bike ran like a champ and i was informed that if this bike is going to sit for a month, it needs to have fuel stabilizer added and run into the carb because of crappy new gas... a bunch of bull but the bike has been running since!!

Hmm - I had some similar probs with my '09 - but mine is an EFI/FI model.

Had the idea that I kept meeting the same garden knome, who had a remote that killed my bike.

Would die mostly when stopping at a red light - and couldn't start again before a random amount of time.

The dealer tried a new charge regulator - even if there was allways plenty of juice on the battery.

Finally the dealer got a re-call from the factory; they had discovered that the bunch of thin wires to the ECU was not sufficiently isolated fromthe frame, leading to chafed wires and lots of fun.

Wiring harness was changed and I have had no problems for close to a year now !

I realize that your bike may not be an EFI/FI model - but as the ecu re-sets itself radomly and You can't start the bike every time - there might be something related here.

Try and yank the wires leading to the ECU - on mine it's located behind the left side cover. If that makes any difference - get a torch and perhaps a magnifier (those wires are thin) and look for chafings.

Sounds like you have a plugged pilot jet. If you used gasoline with ANY ETHANOL, and it sat for 1 month, your pilot jet is plugged. ETHANOL gas plugged up several of my carb motors in 2011. WARNING: DON'T USE GAS WITH ANY ETHANOL ON CARB VEHICLES.

Edited by kx250kev

I had the same exact problem (minus the electrical). The guy who had it before me tried to open it and messed with the carb big time. I changed everything to stock jetting and it still did it. Turns out it was a vaccum leak. A small tear in the diaphragm that lifts the slide. As soon as you crack the throttle it would blubber and stall.

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