Won't Start

Yes im afraid this is another "Help wont start!!" post but I have done basically everything. I have a KLR 250. It sat for a couple years (with gas) and recently I wanted to get it up and running. took the carb out and cleaned it (Boiled in hot water then blew out the needles and other areas with air compressor) and I also took out the air filter and cleaned that. After doing this I attempted to start it, after a couple kicks, the gauges and front light would light up and the engine would rev, but then immediately die. Then it would not do this again for about an hour. I considered changing the spark plug but if it was a problem with the spark plug wouldn't the bike not start at all? Is the idle maybe to high or to low? how would I change that? Was I wrong about it being a problem with the spark plug? Any help is appreciated.

Question, this may be a stupid question... but did you boil the whole carb or did you take it apart? If you took it apart which pieces did you boil? Another question. Is the fuel petcock open? I have done that before when I tried to start the bike and couldn't figure out why it wouldn't start only to find I had forgotten to open the petcock... ha

Question, this may be a stupid question... but did you boil the whole carb or did you take it apart? If you took it apart which pieces did you boil? Another question. Is the fuel petcock open? I have done that before when I tried to start the bike and couldn't figure out why it wouldn't start only to find I had forgotten to open the petcock... ha

I took out the rubber piece that fits over the top and boiled the rest. It now starts but only runs for about 30 seconds (enough time for me to ride it down the block) and then dies. I cant start it again for about 5 minutes. Im assuming that there is too much fuel being released into the carb. 

Im not sure to be honest, but the rubber piece i think you're refering to is the float.. if thats all you took out you may have damaged the needle or something but im not to sure i've never tried boiling a carb i usually clean it thouroughly with carb cleaner

Are you sure you are getting a good flow of gas from the tank ? What does your plug look like after it dies ?

That really sounds like the float level may have been screwed up accidentally and the engine is being starved for gas.

If I read your post right it sounds like you submerged your carb in boiling water and at some point retrieved it and used air pressure to blow out the various circuits. The problem with that is water is very difficult to remove and tends to find a place to lay and cause the kind of issues you are describing. I am thinking you are going to have to take the carb off, completely disassemble it, use carb cleaner rather than water, blow dry areas that can handle air pressure, and reassemble. It is easier to make your float level adjustment with the carb off the bike. Upon reassembly on bike make sure you do not pinch any of the plastic lines that are on the carb. I would take the tank off and dump out all of the old gas and also take the petcock assembly apart to make sure there is not any foreign matter built up in it. Put tank back on bike and pour in a little fresh gas. 


You did not mention it but I hope you changed the oil and filter as part of your routine in getting a bike that has been stored for a couple of years ready to ride. Although I do not believe this has anything to do with the problem, condensation can build up in lots of places.  


Take it out for a ride and let us know how it went.

I have had the same thing happen on my 300. It was a combo of blocked pilot, stuck float valve and overall dirty jets from sitting in old fuel (forgot to drain bowl) What you're describing makes me wonder if your fuel supply, between tank and carb could be hindered as well. I fixed my problems by taking the entire carb apart and very thoroughly cleaning the jets and bowl with carb cleaner. I even sprayed some into a HDPE container to create a little pool and soaked the jets in it for about 20 mins. I also bought a carb rebuild kit for it. It was like 30 bucks. Sounds like a lot, but it comes with bowl gasket, pilot screw and associated parts and a new float valve.  the OEM float valve costs as much as the kit itself. I did all that and now she runs like a champ. Also don't forget to clean out the air cut valve and associated parts too. It's on the left hand side of the carb, its a conical, round, ear looking piece. Make sure your float valve can move freely and the floats are in good shape.


I looked in the TT online shop but didn't see the kit. you can get the carb kit here.




Oh and one word of advice, the rubber diaphragm that is attached to the slide, doesn't seem to like carb cleaner so be care full of that, those are like 120.00.


Good Luck!

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

  • Similar Content

    • By Boondock Patrol
      Hello friends, bought an ‘03 300R yesterday. Love it, but it has a squeaky odometer. Any suggestions for a fix? 

    • By PigPenKLX450
      I bought my KLX in June of this year and this pic was taken earlyer this year I kept forgetting to post it. picture was taken in dove springs. to the left is jawbone cyn way down below and to the right is dove springs. I have gotten many many compliments on how good this photo came out I thought I would share it with all of you.

    • By STi21
      Well, here we go again.
      We had previously posted our Fork Conversion How-To here on ThumperTalk, hoping to help out anyone looking to upgrade their KLX140 or KLX140L by installing a set of KX85 or KX100 Forks. Our goal was to use 100% factory OE parts. No aftermarket anything. And we accomplished that goal. The Bike is drastically improved.
      But it just didn't seem complete. We wanted to finish the job with a new take-off rear KX100 Shock. Don't get me wrong, the KLX140L's rear Shock is actually pretty good. But it is a bit short on travel and refinement. So off we went to eBay to purchase a new take-off rear KX100 Shock. (For the record, the KX85 and KX100 rear Shocks are identical in every way.)
      We would be remiss not to credit art5, codious13 and a few others here on TT for their help and inspiration. A big thank you, guys.
      In order to make sure that anyone and everyone would be comfortable with this conversion, we took lots of pictures and measurements to help make this easy for folks to follow along.
      Here we have our KLX140L with the KX100 front Forks already installed per our previous post. (Eagle-eyed readers will notice that the Bike at this point has KLX140 14"/17" Wheels on it. We have since switched back to the KLX140L's 16"/19" Wheels.) Here we are, ready to go under the knife again:

      We removed the Seat, Plastics and Airbox, and then unbolted the rear Shock. Pictures are worth a thousand words, so here it is:

      Some interesting observations can be found when comparing the KLX140L Shock versus the KX100 Shock.
      First off, the KLX140L OE Spring rate is 5.0kg/mm and the KX100 OE Spring rate is 4.7kg/mm. We stuck with the softer KX100 OE Spring, but a heavier or more aggressive rider may want to re-use the KLX140L Spring.
      Second, the stock Spring pre-load on the KLX140L was measured to be about 80mm. The stock Spring pre-load on the KX100 was measured to be about 70mm. This is measured from the top of the Spring to the center of the top Shock mounting hole. (We ended up staying with the KLX140L's 80mm setting.)
      Third, KLX140L's Shock body is about 35mm longer than the KX100's Shock body. Here is where we find our additional three inches or so of suspension travel.
      Fourth, the KLX140L's Clevis is about 20mm longer than the KX100's Clevis. Not good. We did not want to drop the rear end of the Bike down, so we'll have to install the KLX140L's Clevis onto the KX100 Shock.
      Lastly, the KLX140L's External Reservoir is significantly shorter than the KX100's External Reservoir. Again, not good in this instance. As it stands, it is going to hit the KLX140L's Frame. More on this later:

      Using a Center Punch, Hammer and a Spanner Wrench, we loosened the threaded Spanner Lock Ring and Perch as far as they would go, and then removed the Springs from the Shocks. Nothing to it. Here is the KLX140L's Shock with the Spring removed:

      At this point we needed to switch out the KXL140's Clevis with the KX100's Clevis. The KLX140L's Clevis Bolt is pictured here:

      By simply putting a wrench on both the Clevis Bolt and the Clevis itself, we removed the Clevis from both Shocks:

      Now here was a potential concern. We did not know exactly how the Clevis' adjustment mechanism (AKA Clickers) is attached to the bottom of the Shock's center shaft. We have heard that the Shock can be damaged at this point, so we were very careful during this next step.
      It turns out (Pun intended) that there is a center rod that extends down into the Clevis in order to adjust the Shock's rebound dampening. If this center rod is allowed to slide out, and it did try to, the Shock may discharge and need servicing.
      That being said, just make sure that the center rod stays relatively static during the changeover. No worries here:

      And now we have a KX100 Shock complete with a KLX140L Clevis:

      Now, here things get a bit more interesting. How to get the KX100 Shock to fit into the KLX140L's Frame? Looking at the Frame's rear top Shock Mount, we can see that there is a threaded Collar welded to the Frame. This Collar has a 10mm ID, a 16mm OD and is 20mm long:

      We installed the KX100 Shock into the Bike, but did not install the top Shock Mount Bolt. Not surprisingly, there is a fair amount of bearing free-play in the Shock's lower UNI-TRAK suspension mechanism. Without putting any significant lateral pressure on the Shock, we tilted it to the left, and took some measurements:

      And then we tilted it to the right, and took some measurements:

      There was an easy 16mm of side-to-side play at the top of the Shock. Perfect. If we ground 8mm off the threaded Collar, the Shock should fit perfectly. After covering the Carburetor's intake with Tin Foil in order to keep any debris out, the careful use of an Angle Grinder and/or Dremel Tool was all that was needed. A bit of hand filing at the end is wise to ensure everything is just right:

      Obviously, we now had 8mm of space to the left of the Shock's top mount. What to do here without going aftermarket? Not a problem at all. We removed the two dust seals from the top of the now unused KLX140L Shock and slid out the center Collar. This Collar has a 10mm ID, a 16mm OD and is 19mm long. Again, perfect:

      Using a Dremel Tool, we cut the Collar in half. This way, if we goofed up and ground one of the halves a bit too short, we would have a backup:

      Using a Bench Grinder, we ground down one of the Collar halves to exactly 8mm:

      And finally, the moment of truth. We installed the KX100 Shock with our new 8mm matching Collar and torqued everything down per the specs in the Owner's Manual. The triangular UNI-TRAK Link at the base of the Shock was flipped over and ground down just a bit, as needed, per art5's recommendation. The flipped Link raises the rear of the Bike about one inch and stiffens up the rear suspension a bit. The Link is not visible in this picture, but you get the idea:

      Another view from the left side:

      This picture shows everything in it's place:

      And there you have it. So far, the Bike feels spectacular. Very smooth, very plush and very fun. And everything looks absolutely 'factory'. Awesome.
      Even though we only moved the top Shock mounting point 8mm to the right, well within the lower bearing's range of free-play, we will keep an eye on the bearings to make sure they are not wearing prematurely over the coming years. They are cheap to replace, if need be.
      It would be surprising if tilting the Shock over a mere 1.1458 Degrees will really have any negative impact. Again, no worries. Finally, here is the completed package:

      By the way, we are not trying to take credit here and pretend that we're the first people to put a KX100 Shock on a KLX140L. We're not. We just hope that this helps anyone out there, especially folks who might feel a bit intimidated by this process, to do the same thing if they would like to. It's really not that difficult. Have fun...
      Erik (and my now 14 year old son Tyler)
    • By v55
      Hi Everyone,
      Firstly, good morning. Let me introduce myself: I'm French and I live there. I think there is the better forum for technical issue in the world and would like to find a solution.
      Here is my problem:
      I have a '2009 KLXR, and the surface of the cylinder head which support camshaft (on the right side of the engine) where there is not bearing, is destroyed. Due to that there is a clearance between camshaft and head. I change two times cylinder head and still same issue!
      I'm disappointed! Does someone has the same problem? In your opinion it's due to what? And how to fix it?
      Apologise for my english!) If it is not clear i can join a pic.
      Thank you!
    • By Nick Gavrilis
      Hi everyone, here's my (rookie) dilemma. If you had 1000€ (1.293,551$) and no more, which one of these two bikes would you choose to buy and restore up to the point of being able to trail ride on the weekends? the 4T has 21.000 miles on it and the 2T has 12.000 miles (daily commuting is not an issue here, pure fun and learning how to cope with a dirt bike is, but on a tight budget ) Also any thoughts on reliability, cheap maintenance etc, would be appreciated or if someone has another bike to suggest that suits better for the job i would be more than happy to know about it. Thanx a lot!
      p.s. thumper talk rules!