1995 KX125 "Fuel economy"

My husband has a 1995 KX125 that we purchased used (supposedly it was hardly used before we bought it). While we were out at Hollister on about a 1 1/2 hour ride he ran out of gas near the end and had started the day with a full tank (about 2.3 gallons). We couldn't have rode more than 20 - 25 miles and my KLX140L was still pratically full after the end of the ride.

Any thoughts? Is this normal? This is most annoying. I haven't noticed any fuel leakage, but maybe I'm missing something.

Any thoughts???

Thanks.

you should have got more milage. I did a 30 mile loop at johnson valley with my 125 and i was out just about 32. Sounds like your float height in your carbis off, leaks out of over flow if off. Start by cleaning the carb, all jets, passages with Water hose and compressed air. See where the float height is todetrmine if in fact was off. Check reeds any way. Also, a bike that is not jetted right can have less fuel millage. Lot of black stuff coming from exaust?Get a manual, not hard to clean carb, set float height. Also check for and little cracks around fuel tank, especially around fuel petcock, turn the fuel on and shake the bike while looking at the tank,carb overflow from bowl, to see if its leaking. good luck

you should have got more milage. I did a 30 mile loop at johnson valley with my 125 and i was out just about 32. Sounds like your float height in your carbis off, leaks out of over flow if off. Start by cleaning the carb, all jets, passages with Water hose and compressed air. See where the float height is todetrmine if in fact was off. Check reeds any way. Also, a bike that is not jetted right can have less fuel millage. Lot of black stuff coming from exaust?Get a manual, not hard to clean carb, set float height. Also check for and little cracks around fuel tank, especially around fuel petcock, turn the fuel on and shake the bike while looking at the tank,carb overflow from bowl, to see if its leaking. good luck

I thought so too. Thank you for all of the suggestions, I will be taking a closer look at those items. As for black stuff from exhaust, other than oil leakage from the pipe, no other black stuff exists. I assume that the oil out the exhaust is normal on a 2 stroke yes?

My husband has expressed concern about it and has oil that has splattered on his riding gear from this. I also noticed a little fuel drippage from the overflow, but also had assumed this was normal and it does stop. Any thoughts?

I do have a shop service manual so I will do as you suggested. I will also consider changing out the jets as I have to do the ones on my KLX as well. Any suggestions on the jets for the KX??

if he fell several times, or if the bike was on its side/upside down for a little while with the gas turned on, gas will come out of the overflow tubes on the carburator. if this is not the case, the jetting on the carburator may be to rich. If the exhaust has a bunch of black spooge all over it u are running the bike way to rich. just need to adjust the carb.

Get a JD jetting kit if u dont have experience jetting carburators. they work very well and are easy to install.

if he fell several times, or if the bike was on its side/upside down for a little while with the gas turned on, gas will come out of the overflow tubes on the carburator. if this is not the case, the jetting on the carburator may be to rich. If the exhaust has a bunch of black spooge all over it u are running the bike way to rich. just need to adjust the carb.

No, I am the one that crashes all the time (I'm quite sore today). Sounds like to me that you are right on about it running too rich.

How should I adjust the carb to lean it out a bit? Would jetting be beneficial and if so, what size jets should I consider going to? The bike has an FMF full exhaust on it.

Thanks so much, looks like I am on the right path to solving this issue. :thumbsup:

overflow drippage and black stuff on the exhaust should not be there if jetted correctly. fix it and the bike will bot only have better fuel economy but it will run way better

Thanks!! I didn't think it was right, but it's my first two stroke. I will have a jetting party over the weekend on both the bikes.

I appreciate the help and advice.

No, I am the one that crashes all the time (I'm quite sore today). Sounds like to me that you are right on about it running too rich.

How should I adjust the carb to lean it out a bit? Would jetting be beneficial and if so, what size jets should I consider going to? The bike has an FMF full exhaust on it.

Thanks so much, looks like I am on the right path to solving this issue. :thumbsup:

the first thing to do would be to check what size main jet it has in it right now. you probably only need to go 1 or 2 sizes smaller. If there is still room for improvement, move the needle down 1 or 2 notches and turn the air screw out 1/2 of a turn. there is probably no need to change the pilot jet.

Definately get a manuel if u dont know wat these things are that i am talking about. A manuel should give u diagrams and such. Once again i would also highly recomend a JD jetting kit or u could also ask ur local shop for advice.

oh by the way when i say "move the needle down" you acually have to move the clip on the needle up, thus dropping how low the needle hangs

the first thing to do would be to check what size main jet it has in it right now. you probably only need to go 1 or 2 sizes smaller. If there is still room for improvement, move the needle down 1 or 2 notches and turn the air screw out 1/2 of a turn. there is probably no need to change the pilot jet.

Definately get a manuel if u dont know wat these things are that i am talking about. A manuel should give u diagrams and such. Once again i would also highly recomend a JD jetting kit or u could also ask ur local shop for advice.

oh by the way when i say "move the needle down" you acually have to move the clip on the needle up, thus dropping how low the needle hangs

I do have a shop manual for the bike, so I am covered there. I also checked for a JD jetting kit for his bike and didn't see one (the KX250 was the closest I found). I would much prefer getting a kit as well, I like to spend more time riding and less time wrenching if you know what I mean.

Now once I get the carb out how do I know what size the jets are? The bike is used so there is no telling what they did to the bike before we got it.

Thank you so much for your tips. I'll keep looking to see if I can find a kit.

I used to have a 1995 kx 125, it had pretty good fuel economy( ride at the track for a few hours and it would barely lose any gas)

So yeah there is probably something wrong with your carb. The previous owners of mine had put the wrong carb in there, so we just bought a completly new carb from some shop in NC i think.

The way you jet your carb and set your screws also depends on the exhaust you have. If its an aftermarket like Pro circuit or FMF, you will ahve to look at the website, they should have the jetting specs for your bike

I used to have a 1995 kx 125, it had pretty good fuel economy( ride at the track for a few hours and it would barely lose any gas)

So yeah there is probably something wrong with your carb. The previous owners of mine had put the wrong carb in there, so we just bought a completly new carb from some shop in NC i think.

The way you jet your carb and set your screws also depends on the exhaust you have. If its an aftermarket like Pro circuit or FMF, you will ahve to look at the website, they should have the jetting specs for your bike

Thanks, he has an FMF system on his bike. I will check it out.

It'll be a jetting / carbuerator party at my house considering I also have to jet my KLX too which is running too lean.

Definitely a carb/fuel problem as youve been told, running way rich, maybe a little high on fuel mix ratio as well. The jets will have numbers on them, the higher the number the larger the jet. Findout what stock is, what you have and go from there. On a side note, ronniesmailorder.com has some very thorough diagrams and parts breakdowns for almost every popular ride out there, if youre manual pics are lacking. Hope this helps. Now if I could just get my running problem addressed, we would both be set!

WOW, thanks for all the fantastic information. Best of luck.... to BOTH of us! :thumbsup:

No, I am the one that crashes all the time (I'm quite sore today). Sounds like to me that you are right on about it running too rich.

How should I adjust the carb to lean it out a bit? Would jetting be beneficial and if so, what size jets should I consider going to? The bike has an FMF full exhaust on it.

Thanks so much, looks like I am on the right path to solving this issue. :thumbsup:

Re-jetting will be very beneficial, for more reasons than just fuel mileage. The spooge will go away, the bike will run much crisper and more cleanly and be more responsive, the silencer packing will stay freash much longer, and the power valve assembly won't have to be serviced between rebuilds.

Print this out. It won't tell you what jets to use, but it will tell you how to determine the correct jetting:

Spanky's Jetting 101:

A correctly jetted carb makes a tremendous difference in the torque, midrange pull, top-end pull, and over-rev of your engine. If you have never jetted your bike correctly, you will almost certainly gain some performance at some point in the bike's powerband.

A cleanly jetted pilot circuit can be the difference between having to clutch the bike out of a turn or not. Hard starting when hot or cold, poor response when opening the throttle, reluctance to idle, all of these are symptoms of an improperly sized pilot jet or incorrectly adjusted air screw.

The needle can make all the difference in the world for the power of the machine in most situations, as it controls the throttle range that most riders spend most of their time using.

A correctly sized main jet could mean the difference between being able to rev out high enough to not have to shift one more time at the end of the straight, or the power falling flat on top and requiring you to make that extra shift.

Are you fouling plugs? Many people will tell you all sorts of band-aid fixes, from running less oil, to running a hotter plug. Both are incorrect fixes for plug fouling. It's all in the jetting. An engine that is jetted too rich will have combustion temperatures that are too low to burn the fuel and oil effectively, leading to deposits and wet fouling of the plugs.

Do you have spooge? There are the rare instances where a mechanical issue, such as a leaking wet-side crank seal, can cause spooge. But, by and large, this isn’t the case. In most instances, spooge is caused by rich jetting. It has nothing to do with how much oil you mix in the gas, or how hard you ride. An engine that is jetted too rich will have combustion temperatures that are too low to burn the fuel and oil effectively, resulting in deposits, plug fouling, and spooge. Spooge is nothing more than unburned fuel and oil entering the exhaust.

The only way to know what jetting changes you will need is by trial-and-error. No one can give you jetting specs, because every bike is different, every rider has a different style, and jetting is totally weather dependent. Unless the person telling you what jets to use is riding an identical bike, on the exact same track, at the same time, his recommendations are meaningless. Someone with a good understanding of jetting can get you in the ball park, but you need to do the testing to determine the correct jetting yourself if you want it right.

Jetting is fairly simple, and is a useful skill to learn if you ride a two-stroke and want it to perform at it's best.

It's very important that you start with the pilot circuit, because the pilot circuit affects the entire throttle range. When you are at full throttle, the main jet is the primary fuel metering device, but the pilot is still delivering fuel as well, adding to the total amount of fuel that your engine is receiving.

Before you start to re-jet your bike, you need a clean air filter, a fresh plug (actually you need several plugs to do plug-chop tests for the main jet), and fresh fuel.

One important detail: Make sure the engine is in good mechanical condition. If your engine has a worn top-end, fix it first. Trying to jet a worn out engine is a waste of time. The same goes for reeds that don't seal properly, and a silencer that needs re-packing. Worn reeds will mimic rich jetting, and worn rings will mimic lean jetting.

Before you start the jet testing, Install a fresh plug. Set the float level to the proper specs, an incorrect float height will affect your jetting all across the throttle range.

All jet testing must be done with the engine at full operating temperature.

As already stated, start with the pilot circuit. Turn the air screw all the way in, then turn it out 1.5 turns to start. Start the engine, and turn the idle screw in until you get a slightly fast idle, or hold the throttle just barely cracked, to keep the engine idling. Turn the air screw slowly in, and then out, until you find the point where the idle is fastest. Stop there. Do not open the screw any farther, or your throttle response will be flat and mushy, and the bike may even bog. This is only the starting point, we will still have to tune the air screw for the best response.

Now is the time to determine if you have the correct pilot installed in your carb. The air screw position determines this for you, making it very simple. If your air screw is less than 1 turn from closed, you need a larger pilot jet. If it is more than 2.5 turns from closed, you need a smaller pilot jet. If your engine doesn’t respond to air screw changes, then you either have a dirty carb, or the pilot jet is way too rich. When the pilot jet is way too rich, you are forced to use the idle screw to open the slide so far in order to keep the engine running that the pilot circuit is partially bypassed, and the engine is actually starting to draw fuel through the needle jet.

Once you have determined (and installed it if it's necessary to change it) the correct pilot jet size, and tuned the air screw for the fastest idle, it's time to tune the air screw for the best throttle response. Again, make sure the bike is at full operating temperature. Set the idle back down (the bike should still idle, despite what you read in the Moto Tabloids), and ride the bike, using closed-to-1/4 throttle transitions. Turn the air screw slightly in either direction until you find the point that gives you the best response when cracking the throttle open. Most bikes are sensitive to changes as small as 1/8 of a turn.

The air screw is not a set-it-and-leave-it adjustment. You have to constantly re-adjust the air screw to compensate for changing outdoor temps and humidity. An air screw setting that is perfect in the cool morning air will likely be too rich in the heat of the mid-day.

Now, it's time to work on the needle. Mark the throttle grip at 1/4 and 3/4 openings. Ride the bike between these two marks. If the bike bogs for a second before responding to throttle, lower the clip (raising the needle) a notch at a time until the engine picks up smoothly. If the bike sputters or sounds rough when giving it throttle, raise the clip (lowering the needle) until it runs cleanly. There isn't really any way to test the needle other than by feel, but it's usually quite obvious when it's right or wrong. A too-rich needle can often be felt simply when revving the bike on the stand. The bike will sound rough and raspy when blipping the throttle on the stand. A correctly jetted bike should rev cleanly and crisply.

Last is the main jet. The main jet affects from 1/2 to full throttle. The easiest way to test it is to do a throttle-chop test. With the bike fully warmed up, find a long straight, and install a fresh plug. Start the engine, and do a full-throttle run down the straight, through all gears. As soon as the bike tops out, pull the clutch in, and kill the engine, coasting to a stop. Remove the plug, and look deep down inside the threads, at the base of the insulator. If it is white or gray, the main is too lean. If it is dark brown or black, the main is too rich. The correct color is a medium-dark mocha brown or tan.

Please note that, when reading plugs, the tip of the insulator, threads, etc. are meaningless for jetting purposes. They can tell you a lot of things, but jetting isn’t one of them. Only the mixture ring at the very base of the insulator, inside the threads, can tell you anything about the jetting.

These links should help you to understand reading plugs:

sparkplug.gif

sparkplug%20b-w%20.gif

The slide is also a tuning variable for jetting, affecting the throttle range from 1/8 throttle to approximately 1/3 throttle. If you can’t clean up the small-throttle jetting on your bike no matter how lean you go with the pilot or the needle, the slide is the next step. But few bikes need leaner slides.

Keep in mind, even though this article is intended primarily for two-strokes, four-strokes also need proper jetting to perform right, although they are not quite as fussy as their oil-burning cousins. The only real difference in the two is with the pilot circuit.

Two-strokes have an air screw that you screw in to make the jetting richer, and screw out to make the jetting leaner. Four-strokes, on the other hand, have a fuel adjustment screw that you screw in to make the jetting leaner, and out to make it richer. Their purpose is the same, they just do it in different ways.

THANKS! I actually found that article after doing some more research on Google. Very informative. I've already printed it out and am ready to give it a shot. I doubt I could make it any worse than it already is, but I only know how the bike rides from what the person that rides it tells me (my husband), and I'm the one the uses the wrench, not him so much.

THANKS! I actually found that article after doing some more research on Google. Very informative. I've already printed it out and am ready to give it a shot. I doubt I could make it any worse than it already is, but I only know how the bike rides from what the person that rides it tells me (my husband), and I'm the one the uses the wrench, not him so much.
You found my article with Google??? :lol:

Man, that article has really gotten some mileage. I never dreamed it would start showing up on Google searches when I wrote it...:thumbsup:

You found my article with Google??? :lol:

Man, that article has really gotten some mileage. I never dreamed it would start showing up on Google searches when I wrote it...:thumbsup:

LOL... Google is everywhere, didn't you know? :)

It's a good write up. I only skimmed it, but I highlighted some stuff and think that it's going to get me going in the right direction. I only hope I don't find more problems.

Just to let you know, using less oil than what you have used wont solve the spooge problem, just have to use smaller jets etc. you can have 25:1 and wont spooge every where if jetted right. Where in cali do you live?

when my 94 was a 125, it would go further in 1 tank then a crf250x in 1 tank....

Just to let you know, using less oil than what you have used wont solve the spooge problem, just have to use smaller jets etc. you can have 25:1 and wont spooge every where if jetted right. Where in cali do you live?

That's good to know. I live in Northern California, about 40 miles east of San Francisco.

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