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Jetting a KLX140L

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So I learned something on Dirt Day Saturday.... that my bike needs to be jetted. The thing wanted to die every time I stopped so someone suggested I need to replace the jets.

Can someone point me in the right direction? Where do I get the parts/kit to do the job and is it difficult?

I am pretty mechanically inclined, so I am sure I can handle it.

Thanks in advance.

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How does the motor run other wize, through the rest of the power band? If at idle is the only problem area you might try the following link first. I think your KLX140 has a fuel screw.??

how to confirm your pilot circuit setting

Also, might look at a JD jetting solution.

The engine lugs a little when running, feels like it could run better. It climbed a minimally steep hill fairly easily, but I felt that it could have been better. I have already adjusted the idle screw and it made minimal difference.

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Idle screw or fuel screw?? There's a big difference.

Did you run the test "how to confirm your pilot circuit setting"?

You stated it lugs. Where in the power band is it "lugging"? First 1/4 throttle? 1/2 going all the through 7/8?

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Idle screw or fuel screw?? There's a big difference.

Did you run the test "how to confirm your pilot circuit setting"?

You stated it lugs. Where in the power band is it "lugging"? First 1/4 throttle? 1/2 going all the through 7/8?

It was the screw on top of the carb that I adjusted. I am a newbie when it comes to working on dirt bikes.

It seems to be lugging on the lower end of the power band through to about the middle. Then when I come to a stop, it putters out and dies and I have to start it up again... almost every time. Quite annoying. It's a brand new bike with about 7 hours on it.

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What fuel are you running in it? Ethanol? 100% 91 octane pump gas? How long did the bike sit with the gas in the carb before you rode it again? One week, two, three, since last summer? Or do you drain the fuel out of the carb. after each ride?

I know you said it was new but I didn't know when you purchased it, hence the above questions. Also, has the bike ran like this the entire time you've owned it, or is this a new issue?

I do't have a KLX140 so I've looked up some other threads on TT and it does seem your KLX140 has a fuel screw. So, get your owners manual and look up the "fuel screw" and the "idle screw". We'll want to know what these are, what they do, and what they don't do as we move forward.

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What fuel are you running in it? Ethanol? 100% 91 octane pump gas? How long did the bike sit with the gas in the carb before you rode it again? One week, two, three, since last summer? Or do you drain the fuel out of the carb. after each ride?

I know you said it was new but I didn't know when you purchased it, hence the above questions. Also, has the bike ran like this the entire time you've owned it, or is this a new issue?

I am running 87 octane. The bike never sits longer than 2 weeks between rides. Should I be running 91???

As far as draining the fuel out of the carb, I think so... but I can't be certain. My street bike is fuel injected... I'm not terribly familiar with working on a carburetor motor.

The bike is always hard to start and has been like this since I bought it. I've only had the bike a few months. I bought it brand new right out of the crate.

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Tell you what. Take a look at this thread. There seems to be alot of the same issues you're talking about. You can buy 87 octane in both, Ethanal and 100% gas. Which are you using?

https://thumpertalk.com/forum/archive/index.php/t-611888.html

I do't have a KLX140 so I've looked up some other threads on TT and it does seem your KLX140 has a fuel screw. So, get your owners manual and look up the "fuel screw" and the "idle screw". We'll want to know what these are, what they do, and what they don't do as we move forward.

Need to do this

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SpyderGirl,

Your KLX140L came stock with a 38 Pilot Jet and a 95 Main Jet.

Most folks find that going to a 40 Pilot Jet and a 100 Main Jet to be about perfect. Personally, my Bike is using the stock 38 Pilot Jet and a 100 Main Jet. The 40 Pilot Jet made my Bike a little too rich off idle. (Stuttering and sputtering just a bit.)

Hope this helps...

Erik

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SpyderGirl,

Your KLX140L came stock with a 38 Pilot Jet and a 95 Main Jet.

Most folks find that going to a 40 Pilot Jet and a 100 Main Jet to be about perfect. Personally, my Bike is using the stock 38 Pilot Jet and a 100 Main Jet. The 40 Pilot Jet made my Bike a little too rich off idle. (Stuttering and sputtering just a bit.)

Hope this helps...

Erik

Yes, partially, thanks. Is there a kit you buy or instructions on how to make this modification? Like I said, I am pretty mechanically inclined and learn how to work on things very quickly. I have a shop manual for my bike and know my way around tools.

Thanks for any other help you can give me. 👍

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SpyderGirl,

I purchased the Jets from Cycle Parts Nation online. But any Kawasaki dealer can get them. They are factory option parts. I am sure they are available aftermarket also.

As for how to change them, well, the most difficult aspect of this procedure is accessing the Carburetor.

If you do a search online you will find pictures and instructions on how to change out a Carburetor's Jets. You will need to remove the two bottom screws holding the Bowl to the Carb, and then simply unscrew the old Jets and screw in the new ones. I do not have any pictures to post here, but I am sure you can find plenty without much effort.

Again, I do hope this helps...

Erik

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SpyderGirl,

I purchased the Jets from Cycle Parts Nation online. But any Kawasaki dealer can get them. They are factory option parts. I am sure they are available aftermarket also.

As for how to change them, well, the most difficult aspect of this procedure is accessing the Carburetor.

If you do a search online you will find pictures and instructions on how to change out a Carburetor's Jets. You will need to remove the two bottom screws holding the Bowl to the Carb, and then simply unscrew the old Jets and screw in the new ones. I do not have any pictures to post here, but I am sure you can find plenty without much effort.

Again, I do hope this helps...

Erik

Yes, thank you very much. I actually found that I can get replacement jets from BikeBandit and change both the main and the pilot out for about $20. I am going to try going to a 40 pilot and a 100 main like a lot of people seem to be having luck with. I have a shop manual so I should be able to figure it out.

I also found that I also need to do the jets and check the carb on my hubby's KX125 as well (his is running too rich). I guess I'll be having a jetting/cabuerator party at my house. 👍

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