help a brother out with his kaw!

[dirt ninja]

I just got back into dirtbiking with my recently purchased 2002 kx250 that has a few issues. The first thing i wanted to ask is if it is hard to change out my front fork seals? I ran out of money purchasing this bike and need to save money by swapping them out myself. The next issue i wanted to address is oil&fuel ratio. I went riding for the first time with a fresh batch of fuel that was mixed 42:1 (golden spectro) and fouled my brand new irridium plug with only an hour and a half on it. :bang: My buddies tell me to lean out my fuel ratio to 60:1 (using amsoil) but ive read most other people runing a mixture of either 32:1 or 40:1 with no problems. Ive also read that i should adjust my carburator but dont want to mess with the settings if not needed (Im confused :coocoo: ). For my final question, Does anyone know if it is alright to run a plain ngk plug as opposed to the recomended 10 dollar irridium plug that my kx250 calls for. I went to the kawi dealer and they said the irridium plug is the only plug that my bike calls for. TIA!!!

 

[sick 96 250]

congrats on the new bike man, as for the fork seals i cant really help you, there is a few threads in here somewhere that tells ya how to change em out, so just search around. As for your pre-mix, 42:1 isnt to bad when using a good syn 2cycle oil, i run 40:1 in my RM and any other bikes i have. To lean your bike out you would want to go to 32:1, not 60:1, that will make the bike run richer. I would pick a mix between 40:1 and 32:1, thats more of the avg. As for you fouling your plug, its most likely a jetting issue, do a search and you will find tons of info on that as well, its all about dialing in the carb, it could even be as simple as adjusting the air screw. As for plugs, i have always ran NGK BR8ES, cheap and as long as your jetting is correct they will last long, you dont have to keep running those $10 plugs. Good Luck

 

[dirt ninja]

sick 96 rm250

Correct me if im wrong but isnt a 42:1 premix ratio leaner than 32:1 that your telling me? :coocoo:

 

[snb73]

Guys,

Don't try to "jet" your bike by the premix ratio. This is a common misconception. Pick a ratio between 40:1 and 32:1 and stick to it. Then jet the carb accordingly. Use Eric's guide:

http://ericgorr.com/techarticles/carbtuning.html

http://www.teamgreennews.ca/pdf/KX_Tech_Jetting.pdf

42:1 is richer mixture (more fuel/less oil) 42 parts of fuel to 1 part of oil
32:1 is a leaner mixture (less fuel/more oil) 32 parts of fuel to 1 part of oil

In most cases rich or lean describes the amount of fuel. Too much fuel = a rich condition, too little fuel = a lean condition. In the case of a two stroke motor we are talking about the pre-mix (fuel/mixture) as a whole. A rich condition means too much premix (whatever your chosen ratio) entering the engine. A lean condition means too little premix entering the engine.

Any BR8 series plug should work well for your bike, ie... BR8ES, BR8EG, BR8EIX

http://www.strappe.com/plugs.html

http://www.kaila.net/tl125/tl125ngkcode.html

http://ericgorr.com/techarticles/sparkplugs.html

I used the same plug last season witout fouling once. I use Golden Spectro Synthetic at 40:1

Good luck, Steve.

 

[thing2_and_thing1]

I would consider dropping the fuel to 32:1 if you are "all out" for long periods of time. 40:1 is fine otherwise.

I had the same issue with my 2000 kx250. I pulled the top off the carb and moved the clip in the needle up one position to lean it out and also made more of an effort NOT to putt around and I have not fouled a plug since. Moving the clip takes about 30 minutes and cost nothing. If this does not fix the problem, jetting is next. :nod:

 

[TimberPig]

Guys,

Don't try to "jet" your bike by the premix ratio. This is a common misconception. Pick a ratio between 40:1 and 32:1 and stick to it. Then jet the carb accordingly. Use Eric's guide:

http://ericgorr.com/techarticles/carbtuning.html

http://www.teamgreennews.ca/pdf/KX_Tech_Jetting.pdf

42:1 is richer mixture (more fuel/less oil) 42 parts of fuel to 1 part of oil
32:1 is a leaner mixture (less fuel/more oil) 32 parts of fuel to 1 part of oil

In most cases rich or lean describes the amount of fuel. Too much fuel = a rich condition, too little fuel = a lean condition. In the case of a two stroke motor we are talking about the pre-mix (fuel/mixture) as a whole. A rich condition means too much premix (whatever your chosen ratio) entering the engine. A lean condition means too little premix entering the engine.

Any BR8 series plug should work well for your bike, ie... BR8ES, BR8EG, BR8EIX

http://www.strappe.com/plugs.html

http://www.kaila.net/tl125/tl125ngkcode.html

http://ericgorr.com/techarticles/sparkplugs.html

I used the same plug last season witout fouling once. I use Golden Spectro Synthetic at 40:1

Good luck, Steve.

I've (and everyone else I've been around) always referred to fuel/oil ratios the opposite way, that a rich fuel oil mix has lots of oil, and little fuel, but it will produce a slightly leaner air fuel mix than a leaner fuel oil ratio (more gas, less oil). By your way of referring to it, you are referring to the effect on air fuel mixture directly, instead of the amount of oil in the mix.

Just to be clear, the difference here with changing premix ratios is like a 1% change from 40:1 down to 32:1, or way less than a jet size, so for tuning your jetting correctly, you need to juggle brass, not play with your bottle of mix oil. As said, pick a ratio based upon your lube needs and comfort level, and then jet the bike to get the correct air/fuel mix for proper combustion, don't try and make minute changes with your fuel/oil mix, and expect your problems to be solved.

 

[dirt ninja]

Thanks for the input guys

Im going to start with the air mixture on the carb and work my way down the line with the jetting. Appreciate the brotherly help!

 

[xprojectstevex]

If you want a cheap fix on the spark plug problem then just use a colder spark plug. The number in the spark plug type is the temperature for the plug. I know this is frowned upon by most but if your having a tough time with the plugs and just want to get some ride time in it will work for you. If your not comfortable with jetting your carb then definately don't do it, instead run a colder plug until you can pay somebody to do it. It's a pain in the ass if you don't understand what your doing because trust me you will have your gas tank off atleast 5 to 10 times trying to get it right. On top of it being a pain in the ass if you lean the mixture out too much your top end will wear out alot faster than it should. As for the mixture if I were you I would run stay at 42:1 because that mixture contains less 2 stroke oil... even though like everyone said it's not much of a difference, when times are tight do what you can. Also as thing1andthing2 said moving the clip on the needle up one will probably work and be alot easier for you to do then trying to jet your bike correctly. One last thing... check the gap on your spark plug.. if it is too small it won't burn the fuel efficiently at high speeds.... if it is too wide it won't burn the fuel efficiently at low speeds which both can contribute to plug fouling. Hope some of this helps. If you have any questions just post and I'll see it.

 

[TimberPig]

He's better off in the long run to correctly jet his bike, than try and mickey mouse it with fuel/oil ratio, plug heat range, or any other band aid fixes that mask but don't solve the problem. Correct jetting is relatively cheap, not particularly difficult and will save you money on spark plugs, gas and engine parts. A correctly jetted bike will not foul plugs, and can run a long time on a spark plug, to where you actually wear them out, not foul them and toss them. It will burn less fuel, as you aren't spitting excess fuel out the exhaust, and will have more power. So long as the bike is not set up such that it is lean, the engine life will be maximized, not shortened. Unless you count not being able to ride your bike because you can't keep a plug and gas in the thing because it is set up so pig rich it won't run, as saving your engine life.

 

[xprojectstevex]

I agree with you, no where in my post did I say that a colder plug is the best fix. He simply said times are tight after buying the bike so I'm offering cheap solutions to use temporarily until money is better. Jetting is cheap your right but if you don't know what your doing it's time consuming and becomes guess work. For someone inexperienced in jetting and air/fuel mixtures it's better to let a proffessional do it. In my opinion fouling 1 spark plug doesn't necessarily mean the jetting is wrong. Have you talked to whoever you bought it from and asked them what kind of luck they had with spark plugs?

 

[YZThumper]

When you take the carb apart, take note to what size the current pilot jet and main jet are. Also take note on where the current clip position is on the needle. Before you mess with the air mixture screw, take note of how many turns out it currently is set at. Now get your self a good manual (OEM or Clymer) and compare your carb settings to what stock is. If the previous owner is way off from stock, I'd take the jetting back to stock and start from there.

 

[TimberPig]

If he is fouling plugs already, a colder plug will only make the problem worse. A hotter plug will slightly increase the plug temp and burn off the deposits better.

If money is that tight after buying the bike, that a guy cannot afford to buy a couple $3 carb jets, how is he going to afford the $10 a tank for gas? Especially when a couple $3 carb jets will save more than a few $10 spark plugs.

I'm fairly certain his comment on money being tight was more aimed at the fork seal leak, than the relatively minor cost to tune the bike for his riding conditions. I took his asking about cheaper plugs more to be a comment on the high cost of the Iridium plugs, and how quickly his overly rich jetting is fouling them out.

 

[xprojectstevex]

Look TimberPig whatever man... I gave some advice to get the man some ride time.. if he took it cool if he decided that it sucked and to follow other advice that's cool too.. I didn't put it on here for you to pick apart.. maybe you should find someone else to argue with about this subject. This forum is for throwing ideas out to people who need them not picking each others ideas apart, I'm done talking about it.


I totally agree with yzthumper. I would write everything down before you change it, that's a great idea. Also taking the bike back to stock settings is also a good idea. Most factory bikes come off the line setup a little bit rich for longevity of the engine, the stock settings are also more versatile in different riding conditions, so if there aren't any mods done to the bike such as pipes reeds etc etc you might want to consider keeping it at stock settings.

 

[ellandoh]

simplest thing to do is use this article and the 20$ spent will be at least 10 times cheaper than the money and aggravation spent in the long run.........guaranteed


Spanky's jetting guide:

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. 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.
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.
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. The reason is simple. 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 rejet 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.
Warm the bike completely, and shut it off.
As already stated, start with the pilot circuit. Turn the airscrew 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 idleing. Turn the airscrew 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 airscrew for the best response.
Now is the time to determine if you have the correct pilot installed in your carb. The airscrew position determines this for you, making it very simple. If your airscrew 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.
Once you have determined (and installed it if it's necessary to change it) the correct pilot jet size, and tuned the airscrew for the fastest idle, it's time to tune the airscrew 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 airscrew 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 airscrew is not a set-it-and-leave-it adjustment. You have to constantly re-adjust the airscrew to compensate for changing outdoor temps and humidity. An airscrew 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.
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.
Once you have a little bit of experience with jetting changes, and you start to learn the difference in feel between "rich" and "lean", you'll begin to learn, just from the sound of the exhaust and the feel of the power, not only if the bike is running rich or lean, but even which one of the carb circuits is the culprit.
The slide is also a tuning variable for jetting, but slides are very expensive, and few bikes need different slides, so we won't go into that here.
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.

 

[ellandoh]

if you dont already know how , search around to find out how to tear your carb apart. ive posted the easy way many times. mostly near a spankys jetting guide so search on that. find out the sizes of the pilot and main jet, find out where your air screw is and what it is set at. ride your bike some and describe what it is running like at different throttle openings(NOT RPM's) and we will help you fix your rig in a flash if you want the help or you can go ahead and play with faulty fixes til you get fed up and sell it.

 

[snb73]

When I said this:

42:1 is richer mixture (more fuel/less oil) 42 parts of fuel to 1 part of oil
32:1 is a leaner mixture (less fuel/more oil) 32 parts of fuel to 1 part of oil

I meant this:
http://justkdx.dirtrider.net/carbtuning.html

Before we get into the different parts of the carburetor and how they effect gasoline delivery I want to stop for a second and define the terms RICHER and LEANER. I know these terms can cause some trouble for those who are new to the sport or new to carburetor tuning and they are often used incorrectly. The terms RICHER and LEANER refer to the amount of GASOLINE being delivered to the engine and not the amount of oil. If you’ve done a plug reading at wide open throttle and the plug indicates you are running rich ( dark brown to black ) this is an indication that too much gas is being delivered to the engine and not too much oil. I know there are people that will say "You’re running too rich, try to change your premix ration from 42 parts of gas to 1 part oil (42:1), to 50 parts of gas to 1 part oil (50:1), that should lean things out a little ". This is in fact increasing the amount of gasoline ( 8 more parts of gas for each part of oil ) and causing the engine to run RICHER rather than leaner. If you remember richer and leaner are referring to the amount of gasoline being delivered this will all make much more sense.



This is from Eric's web site:

Fuel and Oil Mixture Ratios
When we talk about the "fuel" in the air-fuel mixture for a two-stroke engine, we are really talking about a mixture of fuel and oil. If you richen the pre-mix ratio (20:1 as opposed to 30:1) there is more oil and less fuel in the same volume of liquid, which effectively leans the air-fuel ratio. And this fact gives the clever tuner one more tool to use when the correct jet is not available or when none of the standard jets are exactly right. You can richen the jetting by slightly reducing the pre-mix ratio (less oil). You can lean the jetting by increasing the pre-mix ratio (more oil). The best part is that changes in the pre-mix ratio affect the jetting over the entire throttle-opening range, but the changes in ratio must be small to prevent excess wear from lack of lubricating oil or fouled plugs from too much oil.

Pre-mix oils are formulated for a fairly narrow range of pre-mix ratios. You should examine the oil bottle for the oil manufacturer's suggestion on the pre-mix ratio. All production two-stroke dirt bikes have a sticker on the rear fender suggesting that you set the pre-mix ratio to 20:1 That sticker is put there for legal purposes. Always refer to the oil manufacturer's suggestion on pre-mix ratios. In general, small-displacement engines require a richer pre-mix ratio than do large-displacement engines because smaller engines have a higher peak rpm than larger engines. The higher the engine revs, the more lubrication it requires.

Good luck, Steve.

 

[TimberPig]

Look TimberPig whatever man... I gave some advice to get the man some ride time.. if he took it cool if he decided that it sucked and to follow other advice that's cool too.. I didn't put it on here for you to pick apart.. maybe you should find someone else to argue with about this subject. This forum is for throwing ideas out to people who need them not picking each others ideas apart, I'm done talking about it.


I totally agree with yzthumper. I would write everything down before you change it, that's a great idea. Also taking the bike back to stock settings is also a good idea. Most factory bikes come off the line setup a little bit rich for longevity of the engine, the stock settings are also more versatile in different riding conditions, so if there aren't any mods done to the bike such as pipes reeds etc etc you might want to consider keeping it at stock settings.

I'm not trying to argue with you, or pick your posts apart, I'm trying to prevent misinformation and half truths from being passed on. Band aid fixes like what you are suggesting do not actually solve the problem, they only mask it which complicates his life when they don't work. It is better to do the job right, and rejet the bike, than to try and hide it with plug changes and premix. All that does is make it last a little longer between plug fouling.

 

[TimberPig]

snb73,
I'm not disagreeing with you at all. I understand air fuel ratios and how it is changed. I have simply never heard fuel/oil ratios described by their effect on air/fuel ratio, as you are saying. I have always heard and described the fuel/oil ratio by how much oil is in it based upon the lube it will provide to the engine with a lean mix having little oil hence lean on lube to the engine (with a rich air/fuel mix resulting). The problem here is that someone should come up with a completely different term to describe a mix with lots of oil in it, to prevent the confusion caused by using rich/lean to describe both the air/fuel mix and the fuel/oil mix. How about thick for a mix with lots of oil and thin for one with little oil, at least it describes the mix instead of the confusion between fuel/oil and air/fuel mixes as with rich/lean. Save the rich/lean for the air/fuel and use that for fuel/oil mix?

 

[FruDaddy]

When I first started riding my 04 KX250, I fouled a couple plugs real quickly. I do not know what premix was in the tank, and the previous owner was significantly more aggressive than me. He has provided me with the jets to bring the bike down to my level, however, by using a B7 plug (due to my ability, will switch to an 8 when I get fast) and going to 40:1 91 octane:Motul 800, I have had no problems. Please keep in mind, I would have changed the premix anyway since it is what I run in my son's bike. And the jetting now and in the future will be based on this ratio.

 

[dirt ninja]

Great responses guys.. Really appreciate the clarification.

I really appreciate the help and the knowledge thats being shared here by all of you! :cool: This is what i did tonight as far as adjustments: I took the carb out and set the clip to the top position (moved the needle one position) which is supposed to lean the bike out by sinking the needle into the main jet more. :think: (thats what i read) I cleaned and re-oiled the filter for maxium air flow and adjusted the air to fuel screw on the side of the carb back to stock adjustment which is one and a half turns. (It was at set at two full turns by the previous owner) I also plan on repacking the silencer tomorrow so theres no doubt about that part. Im also going to use my fuel that i made up on last Sunday (42:1 golden spectro synthetic) I made this adjustment because i read from things2_and_things1 wrote that i could make a simple adjustment by moving the position of the needle up one which leans the bike out. Guys feel free to chime in if you think im making a mistake. I'll let you know how the bike turns out when i test it. :)

;

 

[xprojectstevex]

Just so you know... if you put the air screw back to stock that will make the mixture richer than it is. Keep in mind that the air screw really only effects about the first 1/8 of the throttle turn... so moving that is only going to help you if your fouling plugs while your just putting around and barely moving. If you do decide to stick with moving the air screw to 1 1/2 your most likely going to need to move the idle screw in a bit to make it idle without stalling out. The clip position is a good move because you are most likely fouling plugs at mid speed range which is exactly what the clip position effects: 1/8 to a little past 1/2 turn on the throttle. I'm not 100% sure but stock clip position is in the middle slot of the 5 slots.. if your in the top slot then it sounds like the last owner had already leaned out a bit from the stock position.. if in fact you are in the very top slot on the needle if I were you I would definately take the carb all the way off and put the jets, the air screw, and needle clip position back to stock settings and start there. Write everything down that it was set to when you got it including jet sizes. Also on the needle there is a part number on it below the notches.. you want to look at that and see if that's even the stock needle and if not write it down and get everything set up as stock. Setting the bike's carb up totally stock is the best starting point on a used bike that is new to you.

 

[dirt ninja]

I just looked up the stock position on the team green url and it specified that stock position for the needle was #2 position and i moved it to the #1position to lean the bike out. Hopefully this will work or we move to the jet kit next.

 

[xprojectstevex]

Oh ok, I wan't quite sure about the kawasaki settings.. good move. Yeah if that doesn't help it go with all stock carb settings and see what she does.

 

[dirt ninja]

figured it out

just wanted to let all the guys that helped me out during my problems. After i changed the needle position and rode my bike, I noticed that the bike was lazy or sluggish :bang: so i put the needle back to the factory setting and tried my friends suggestion by running my oil mixture 60:1. I took my bike out for a ride this weekend and had no problem with this mixture. I than yanked my plug out and noticed that it was just about perfect :ohmy: (light brown tint with very very minimal oil deposits on plug. I guess I should of followed the oil manufactures suggestion but i didnt because i read that just about everyone at this forum runs about 32:1 to 40:1 on their bike. I have however learned alot about jetting now that you all have enriched me with. :cool: Once again thanks again. :)

 

[theKDX200rider]

Solutoin: beat the life out of it with a hammer(that's what I do)