OK, I just purchased a perfect 1999 KX250, FMF pipe, FMF Q Series Silencer, renthal bars, bla, bla, bla. From a race point of view the bike rocks; however, I'm not racing the bike. I'm doing the woods thing. I went out with my buddy who has a KDX220 2002 and the bike just rocks with low gears and lots of quick power for nice wheel stands. What are some of the mods I can make to make the KX250 a better woods bike? I go down hills slow and I have to put in the clutch so the engine won't stall. Then the bike tends to load up some so, the quick wheel stand just isn't there. No, I don't want to buy a KDX220, the KX250 is perfect for my size. Any thoughts would be appreciated.
KX250 mods for more woods friendly
- Thread starter lcwarnke
- Start date
If it were my bike I would do the following:
-hotter plug
-flywheel weight
-larger rear sprocket
-soften suspension, new springs
-add protection, bark busters, skid plate etc..
-hold on tight
Also check your jetting, the a/f screw can make a big difference off idle.
If you still want more then porting for low end or a big bore would really help.
-hotter plug
-flywheel weight
-larger rear sprocket
-soften suspension, new springs
-add protection, bark busters, skid plate etc..
-hold on tight
Also check your jetting, the a/f screw can make a big difference off idle.
If you still want more then porting for low end or a big bore would really help.
Last edited:
Wow, what a small world. My buddy just purchased a very similar 99 KX250 and since he's just getting back into riding, I was a little worried he'd get himself into trouble when the powervalve opened up.
We went on the maiden voyage today for him and his bike. Since I had heard it done before I went ahead and disconnected the powervalve (externally) and wala instant KDX250. I rode the bike for about 10 minutes and actually liked it for the type of tight and open trailriding we were doing. Very versatile and safe for the novice. I was worried that maybe the valves would stick open, but it was just the opposite. It had great low end, decent mid, and flat top end, so the valves were definitely shut. Perfect powerband to go riding with your buddies KDX220!
Forget opening up your wallet for now and do this mod...it works! Also, the great thing is you can always re-connect it or disconnect it for free. Bottomline is my buddy was happy as could be, had no incidents, and the bike performed flawlessly throughout the day.
We went on the maiden voyage today for him and his bike. Since I had heard it done before I went ahead and disconnected the powervalve (externally) and wala instant KDX250. I rode the bike for about 10 minutes and actually liked it for the type of tight and open trailriding we were doing. Very versatile and safe for the novice. I was worried that maybe the valves would stick open, but it was just the opposite. It had great low end, decent mid, and flat top end, so the valves were definitely shut. Perfect powerband to go riding with your buddies KDX220!
Forget opening up your wallet for now and do this mod...it works! Also, the great thing is you can always re-connect it or disconnect it for free. Bottomline is my buddy was happy as could be, had no incidents, and the bike performed flawlessly throughout the day.
- Thread starter
-
- #4
Great ideas. I did put on Bark Busters and pipe guard, but need to put on the skid plate. I'll need to look into the power value suggestion. Easy one to make. Any down side to disabling the power valve? Also, how do you pick what size fly wheel weight to get? I'm currently running a 48 tooth sprocket, but I also have a 49 that I could pop on as well.
Last edited:
- Nov 7, 2001
- 1,234
- 0
Try the flywheel weight before disabling the powervalve. It will definitely smooth out the hit when the valve opens. Once you get used to the power delivery you will rely on the surge of power.
Regarding the weight issue, general advice is heavier for woods and lighter for mx. Steahly makes a 13oz for your bike. If that sounds like too much they also make 7, 9, and 11. Maybe someone with your bike set up for woods will chime in. Good luck, great bike by the way.
Regarding the weight issue, general advice is heavier for woods and lighter for mx. Steahly makes a 13oz for your bike. If that sounds like too much they also make 7, 9, and 11. Maybe someone with your bike set up for woods will chime in. Good luck, great bike by the way.
I know I have a 310, but the 9oz on my bike did very little to take away the hit. The hit's still there it's just more tractable now. I'd say 11 would be a good weight given your application. If it were an '01 like mine where they lightened the flywheel from the factory (and kinda took away the KX feel of the bike) I would go with the 13.
Try disconnecting the powervalve just to try it. You might like and it's free! You can always add the flywheel weight and re-connect the powervalve later.
Try disconnecting the powervalve just to try it. You might like and it's free! You can always add the flywheel weight and re-connect the powervalve later.
jmics19067
LIFETIME SPONSOR
- Jan 22, 2002
- 2,097
- 0
look up any and all posts on jetting and learn how to jet and read plugs. Raise the idle a bit to keep the bike from stalling on long downhills and tight turns but dont just let the bike set and idle while you take a break. Once you have the bike running clean and your willing to toss some money in the performance department my order would be flywheel wieght and either reeds and/or reed block that would help you with the type of riding your into. The 49 tooth sprocket will help getting you up to speed out of slow situations but the 48 will help the power come on a little smoother.
if you want to feel like playing around a bit try vp racing C12 fuel. A bit expensive anywheres from 3$ to 6$ a gallon depending on where you live but once jetted my bike had awesome throttle control.
I have a 94 yz250 with a stock cylinder and head fmf gnarly pipe and spark arrestor, 11 0z flywheel wieght and a boyeson rad valve and I am very happy with its performance. I ride in a lot of varying conditions,tight woods with lots of up and down switchbacks with tons of rocks one day /weekend then the next deep sand pits.And one of the best things I have found is to go out one weekend and try a differrent fuel and jet for it. write down the jet settings. I basicly have two completely differrent bikes swithing from C12 <nice smooth linear power> to vp racing CMP fuel<lotsa hit abrupt power NOW!>. after you learn how to jet properly and you play with the different fuels and find what you like for certain situations you can seriosly befuddle your buddy by letting try your bike and he will be wondering what you did to make the bike act so different. And all you did was drain the fuel tank and change some jets in the carb :D
if you want to feel like playing around a bit try vp racing C12 fuel. A bit expensive anywheres from 3$ to 6$ a gallon depending on where you live but once jetted my bike had awesome throttle control.
I have a 94 yz250 with a stock cylinder and head fmf gnarly pipe and spark arrestor, 11 0z flywheel wieght and a boyeson rad valve and I am very happy with its performance. I ride in a lot of varying conditions,tight woods with lots of up and down switchbacks with tons of rocks one day /weekend then the next deep sand pits.And one of the best things I have found is to go out one weekend and try a differrent fuel and jet for it. write down the jet settings. I basicly have two completely differrent bikes swithing from C12 <nice smooth linear power> to vp racing CMP fuel<lotsa hit abrupt power NOW!>. after you learn how to jet properly and you play with the different fuels and find what you like for certain situations you can seriosly befuddle your buddy by letting try your bike and he will be wondering what you did to make the bike act so different. And all you did was drain the fuel tank and change some jets in the carb :D
Try a different taper needle. I am using a ‘N3EJ’ needle in my 02 KX250. It removed the hit and created an extremely linear power band. It is excellent for trail riding, vary controllable. The only way the bike could get away from you is if you mistakenly twist the throttle wide open.
The stock needle in the 02 (NAFF) is a triple taper and dumps an extra amount of fuel at about 1/4 and 5/8 throttle. This gives the bike a hit in the power band. The ‘N3EJ’ is a double taper needle and delivers the fuel more evenly over the entire range of throttle positions.
Since I switched to this needle, I have also not fouled a plug. The needle is leaner then stock, so you will have to experiment with the pilot and the main. I am currently using a 55 pilot, 170 main, and the needle is in the third clip position. My bike also has an 11oz flywheel weight and an FMF Q Spark Arrestor.
Good luck
The stock needle in the 02 (NAFF) is a triple taper and dumps an extra amount of fuel at about 1/4 and 5/8 throttle. This gives the bike a hit in the power band. The ‘N3EJ’ is a double taper needle and delivers the fuel more evenly over the entire range of throttle positions.
Since I switched to this needle, I have also not fouled a plug. The needle is leaner then stock, so you will have to experiment with the pilot and the main. I am currently using a 55 pilot, 170 main, and the needle is in the third clip position. My bike also has an 11oz flywheel weight and an FMF Q Spark Arrestor.
Good luck
If you don't have the service manual, go to www.buykawasaki.com and look up your year's picture diagrams on the powervalve assembly. Actually , howwever, it's almost easier than changing the clip on your carb needle.
Pop the pipe off (remove silencer first, remove springs at the pipe/cylinder junction, remove the 8mm and 10mm bolts that hold the pipe in place, and gently remove the pipe without dinging up the backside of your right radiator).
Once the pipe is off, you'll see a little plastic cover. Remove the 2 8mm bolts and you'll see the mechanism that opens your valves as the rpms increase. Pretty self-explanatory after that.
There a little clip that holds the "wheel" to the powervalve actuator shaft that is connected to the powervalves in the top end. (my term...I don't know what Kawie calls it!!) Remove the clip gently and not while in the dirt. Don't lose it!!
Place a srewdriver at an angle behind the arm connected to the lower end and gently pull towards you to take wheel off while using a punch to try to push the powervalve shaft away from you and towards the engine to free the wheel. Try to keep the wheel in alignment as it makes it easier to pull off the powervalve shaft.
When it's all said and done, you should end up with a clip, the wheel, and a washer. When you do a top end, you'll have to disconnect the powervalve anyway to remove the cylinder and replace the piston. So consider this good practice.
Good luck!
Pop the pipe off (remove silencer first, remove springs at the pipe/cylinder junction, remove the 8mm and 10mm bolts that hold the pipe in place, and gently remove the pipe without dinging up the backside of your right radiator).
Once the pipe is off, you'll see a little plastic cover. Remove the 2 8mm bolts and you'll see the mechanism that opens your valves as the rpms increase. Pretty self-explanatory after that.
There a little clip that holds the "wheel" to the powervalve actuator shaft that is connected to the powervalves in the top end. (my term...I don't know what Kawie calls it!!) Remove the clip gently and not while in the dirt. Don't lose it!!
Place a srewdriver at an angle behind the arm connected to the lower end and gently pull towards you to take wheel off while using a punch to try to push the powervalve shaft away from you and towards the engine to free the wheel. Try to keep the wheel in alignment as it makes it easier to pull off the powervalve shaft.
When it's all said and done, you should end up with a clip, the wheel, and a washer. When you do a top end, you'll have to disconnect the powervalve anyway to remove the cylinder and replace the piston. So consider this good practice.
Good luck!
DEANSFASTWAY
LIFETIME SPONSOR
- May 16, 2002
- 1,192
- 0
Better l;isten to that motor real well or retard the timing if you disable the P/V because it might start banging up top and might burn a hole in the piston esp if youve got it leaned out for the woods. Might start detonating on top because your not bleeding off thev compression. May not be a problem but I would check it out . A company also used to make carb intake restrictors that would install in the venturi of your carb . Yhat could tame it a bit and maybe help out also would maybe give you better throttle response but then on a 99 KX 250 youre not really searching for more anyway.
I concur with the retard, but oh so slightly or in fact you will heat up the motor. However, this is just a trial for him. He may not like it!
I rode my buddies stock 99 with powervalve disabled running a PC pipe on pump. I ran it pretty hard around a tt track (with lots of revs until I adapted to the motorr) for 30 minutes and the outside temp was 90 degrees. Never once did the engine give me a warning sign of trouble. In fact, I stopped revving in because nothing was there to rev! It just built from a nice low end into a decent midrange with nothing on top. So, I just stopped using the top!
Now that you mention it, my bikes been down for a re-build so I borrowed the very same bike for MX practice (powervalve reconnected thank you). Side note: Ever try one of those Moto Jack Rack's. On its maiden voyage it passed with flying colors! Definitely a stout unit and easy to operate.
Anyway, it was another 90 degree day and after about 20 minutes of hard outdoor style MX on a dry track with a lot of wheelspin, the bike started pinging a bit with the powervalve re-connected. The stator plate's in the stock position, so it could probably use a little adjustment or step up to race gas.
Bottomline, pay attention to the motor, but I don't believe it's going to be an issue.
I rode my buddies stock 99 with powervalve disabled running a PC pipe on pump. I ran it pretty hard around a tt track (with lots of revs until I adapted to the motorr) for 30 minutes and the outside temp was 90 degrees. Never once did the engine give me a warning sign of trouble. In fact, I stopped revving in because nothing was there to rev! It just built from a nice low end into a decent midrange with nothing on top. So, I just stopped using the top!
Now that you mention it, my bikes been down for a re-build so I borrowed the very same bike for MX practice (powervalve reconnected thank you). Side note: Ever try one of those Moto Jack Rack's. On its maiden voyage it passed with flying colors! Definitely a stout unit and easy to operate.
Anyway, it was another 90 degree day and after about 20 minutes of hard outdoor style MX on a dry track with a lot of wheelspin, the bike started pinging a bit with the powervalve re-connected. The stator plate's in the stock position, so it could probably use a little adjustment or step up to race gas.
Bottomline, pay attention to the motor, but I don't believe it's going to be an issue.
SFO
LIFETIME SPONSOR
- Feb 16, 2001
- 2,001
- 1
The difference in delivery between a flywheel weight on a peaky cylinder and a cylinder ported for linear power is dramatic.
I found the flywheel weight to create throttle response issues without eliminating the "HIT".
I had eric port my Fe_Princesses ktm 200 for linear power and at first it was a super dog, until I removed the 12 oz flywheel weight.
Now it has a very linear delivery with nice throttle response.
I would do it again in a heart beat.
Every 200 owner who has ridden it wants the same mods.
You can get really twisted up dealing with symptoms or just go to the heart of the problem.
120$ is cheap.
I found the flywheel weight to create throttle response issues without eliminating the "HIT".
I had eric port my Fe_Princesses ktm 200 for linear power and at first it was a super dog, until I removed the 12 oz flywheel weight.
Now it has a very linear delivery with nice throttle response.
I would do it again in a heart beat.
Every 200 owner who has ridden it wants the same mods.
You can get really twisted up dealing with symptoms or just go to the heart of the problem.
120$ is cheap.
SFO, point well taken. However, it's far cheaper to try this out. Since lcwarnke sounds like he's fairly intimidated with the power delivery of his KX, the powervalve option is not too far fetched.
BTW, 200's are way cool. I'm going to try to throw a leg over an '03 SX just for fun. I think it's going to be a great combo!!
BTW, 200's are way cool. I'm going to try to throw a leg over an '03 SX just for fun. I think it's going to be a great combo!!
woods_rider1
Member
- Sep 27, 2001
- 355
- 0
As with any new bike you aquire, start out with Jetting and suspension. Jetting will optimize your power delivery, and make your carb deliver fuel efficiently. If you want to lessen the hit in your power delivery, try the double taper needle as suggested earlier, or even consider a single taper, I use them in my KTM for woods riding and they are SWEET!!!Suspension setup is for performance as well as safety, get it set up for your weight and terrain, for woods riding you might need a revalve, but at a minimum set it up for your weight.
DEANSFASTWAY
LIFETIME SPONSOR
- May 16, 2002
- 1,192
- 0
KX 250 Mellow out
Those FMF 2 stage Ignitions were going away at bargain prices for certain models and I think one of the applications was the KX . You might want to check that out also I think they were like @ $100. Maybe you could retard the base timing and use one for mellow and one setting for hyperdrive? Just a thought . We used one on a 01 KX 250 and thought it worked good .
Those FMF 2 stage Ignitions were going away at bargain prices for certain models and I think one of the applications was the KX . You might want to check that out also I think they were like @ $100. Maybe you could retard the base timing and use one for mellow and one setting for hyperdrive? Just a thought . We used one on a 01 KX 250 and thought it worked good .
- Thread starter
-
- #21
Here's the thing. The KDX220 that I rode (2002) had great bottom. Flip of the rist and the front end easily would come off the ground and pretty smooth at that. My KX250 (1999), seems to sputter at the low end. Mid to top end the KX fly's. I guess when I compare the KDX to the KX, I see the KDX as geared much lower with great low end throttle response.
If I can get my KX250 go jump out of a slow start without sputtering and if I can get my KX to do down a hill slowly without me having to always pull in the clutch, I'll be happy. I loved how how I could go down a hill pretty slow on the KDX and not have to pull the clutch. Also, poping the throttle to bring up the front tire anytime you want is also very desirable.
But, I'm 6'2", 200lbs and the KDX 220 actually felt a little small for me compared to my KX250. I think size of the rider can play a big part in choosing which bike as well.
I've got the FMF pipe, FMF Q Silencer and just put a 50 tooth sproket on. I still need to hit the hills, but my guess is that my jetting may be out of whack.
If I can get my KX250 go jump out of a slow start without sputtering and if I can get my KX to do down a hill slowly without me having to always pull in the clutch, I'll be happy. I loved how how I could go down a hill pretty slow on the KDX and not have to pull the clutch. Also, poping the throttle to bring up the front tire anytime you want is also very desirable.
But, I'm 6'2", 200lbs and the KDX 220 actually felt a little small for me compared to my KX250. I think size of the rider can play a big part in choosing which bike as well.
I've got the FMF pipe, FMF Q Silencer and just put a 50 tooth sproket on. I still need to hit the hills, but my guess is that my jetting may be out of whack.
Icwarnke, I like your ideas with the KX250. I have a '01 KDX 220, and the mods that I have done to it, we'll just say it isn't slow anymore. It's all what you get used to. I had thought about doing your idea, but then I came across the KDX at a steal, and couldn't pass it up.
Have fun and enjoy! :aj:
:yeehaw: :yeehaw:
Have fun and enjoy! :aj:
:yeehaw: :yeehaw:
Icwarnke u have a jetting problem that's all.it's making the hit worse than it probably is and causing ur low speed and load up issues.the idle/ off idle carb circuit is messed then it gets to the circuit that is right on and boom ur off...unsavory to say the least.a poorly tuned carb magnifies a violent hit .with a properly tuned carb whatever the hit is ,it's more predictable and controlable jmo.
I'm not sure what's wrong with the kx250, but my bike picks up the front tire in every gear, stock. Get it running good, leave it stock and abuse the clutch - much more versatile, and WAY more fun. I was concerned about using an mx bike in the woods, I bought a 99 RM250, and I've just geared it way down. It's a capable bike in the woods.