KLX-140L won't go past 5mph

Hello All, I'm new to this forum but hope to get to know it! :bonk:

So, I was riding my KLX-140L after doing some small jumps, and all of a sudden, I had a loss of power, to the point where the bike could only go 5 mph in any gear. :excuseme:

I turned the bike off and started it again, and still had no power, so I pushed it back to my garage ( I was in my backyard/orchard ) I unscrewed my oil cap, and smoke poured out of where the oil should be, ( I had the correct amount of Oil in the bike ) I let it cool down for about an hour and started it again, and I could get to about 7mph, not really any faster.

Before the problem, I had had trouble shifting out of neutral, but then I rode for 2 hours and it ran perfectly, jumped perfectly, went fast, etc ( it was riding VERY good )

When I'm in neutral I can rev the engine perfectly, ( so I don't think it's the throttle cable ), when i shift into gear is when the problem starts.

Another odd thing is that once I'm moving in first or second gear, I can ride at extremely slow speeds without the bike stalling....... normally at around 5 mph the bike would struggle then stall - but now it doesn't sturggle at all to go 5 mph.... any thing past 5 and well you can't get there

I tried to explain my prob as best as I could, my neighbor thinks it could be a loss of compression or a problem with the C clip on the carb.... ( The carb needle did have to be replaced 2 months ago )

The bike is only 5 months old, and just has weekend riding on it ( it's basically new ) so I don't think it could be a compression prob,

Any help is MUCH appreciated!

I'm not a 140 owner but I'm going to take a stab. If the engine revs good without a load and the bike in neutral, It could be the carb. If the C clip came off the needle, it would most likely fall further into the main jet causing the engine to starve for fuel under load. How does the clutch feel? Can you push the bike in gear with the clutch lever pulled in? How much free play is in the cable or lever before you feel resistance? You pushed it to the garage so the brakes aren't dragging. Start with the carb. Welcome to the Best section on TT. Go Green :excuseme:

OK, so I went over the whole bike today

1st, I checked the air box, and the element is perfectly clean, so thats not it

2nd, Checked the carb, the C clip IS on the carb, so thats not it

3rd, I tried to ride the bike and it acted exactly the same as yesterday :excuseme:

Basically, it rides like I have the choke engaged when it's not engaged, it feels like the gas/air mixture isn't right - which would obviously be a carb related prob, but I wen't over the entire carb and it seems fine

I then turned the choke on to try and ride, and it struggled horribly but didn't stall, so I turned it off after 20 feet.....

I went over the entire bike and it seemed fine - my ( old school ) grandpa thinks that it must have some dirt stuck in the fuel line somewhere, but I can't check that - so I'm probably gonna have the dealership come out and get it :smirk::foul::foul::bonk::bonk: I hate what they charge!

check and make sure sure you dont have a vacuum leak between the carb and engine. might be a crack in the rubber or something like that. Did you take the carb apart and blow out all passages with carb cleaner? Can you see through all the jets?

Wasnt there a post a while back about the rubber cap on the intake side deteriorating & causeing problems? Might be worth a check - quick & easy.

Pull apart the carb and clean out the main and pilot jets they clog easily, had this happen several times to mine, till i switched to the 24 mm carb

check all the electrical connections. If you have some dirty or corroded connections it may get enough juice at idle but not enough when at higher RPM's.

Get a small tube of dielectric grease from the hardware store and put a gob on every connetion including frame grounds.

Have you replaced the spark plug?

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 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!
    • By MostWanted117
      I have a cr85 and i have had it for a few years now. my uncle says that he wants me to get a more reliable bike. there have been a lot of options but I have narrowed down to the klx140l. I have been doing some research and found that the cr has about 10-15 more horsepower than the klx. this got me worried because I don't really want a bike that is any slower. I am sick of finishing the ride early because there is always something wrong with it. I don't know if I should keep the cr or get a more reliable bike and have longer rides.
      could people please give reasons why they think whatever they were thinking. don't just say things like " go the klx" or "the cr is way better".
      could people also bring up any other bikes that could be good ( don't want a cheap Chinese bike)
      I am 5'2 and weigh about 45-50kg ( 100-110 pounds)
      I do decent and long trail bike riding