kdx250?????????

[kdxdumb]

need help please kdx250????

Alright I have a few questions maybe someone can help me with. 1st of all this is the first kdx250 I have ever owned. It is a 91 kdx250. What is the gas to oil ratio? Also on a 91 kdx250 is the side of the motor stampes kx250 or is this not the original engine. The reason I ask is because this thing seems to have alot of power. I can wheelie in the first 3 gears and I do not know if it is supposed to have that much power or not. I raced a guy up the street with a 01yz250 and he only beat me by half a bike. I am looking to take it to a mx track so what can I do to the suspension to tighten it up some? Last but not least I am having trouble getting it to idle. When I tighten the idle screw it idles just fine but I seem to lose power is that normal or could it be something else? Any help would be very helpful.

 

[43Duc748]

Welcome to the wonderful world of the KDX250. First off, the stock jetting is crap, so if your jetting is stock, fixing it will most likely take care of your idle problem.

As for the engine stamp. It's not a different engine. The KDX250 uses a KX250 (1988 I beleive) engine w/ a ride ratio tranny. You're right, it has lots of power, especially once you get on the pipe.

The suspension sucks. There is a lot of advice out there as to what to do to remedy it. Best bet is to replace the front forks with a like year KX250 front end and wheel. Otherwise, some have had moderate success w/ a revalve and heavier fork oil. I never messed with mine - I simply adapted my mediocre riding skills to work with it.

Anyway, I've compiled some tips here:

http://www.garage.whatburns.com/KDX2.htm

Good luck with it. I've enjoyed mine a lot... unfortunately I've since crossed over to the dark side w/ a WR426 - I still have my KDX though...

 

[mgouras]

I recently bought a 91 KDX250 and found that Web site very informative.
Do a search of KDX250 in the forums here for even more info (much of it by 43duc748)!
IN term so foil to gas ratio, I bet it is like most two strokes. The factory recomends 32:1. But with different oils, such as synthetic, and jetting to match, you can run thinner ratios.
For fork springs more sutiable to the MX, you can go to the race tech Web site. The idle problem could be a lot of things. Does it die at idle with the screw set per factory recomendation? Check for air leaks. Carb cleaner sprayed on the potential leak areas can give an indication. Does the float work? Is the float level correct? Just guessing in the dark here, and I am no 2-stroke pro ...

 

[43Duc748]

I'm sorry, I forgot the oil to gas ratio part of your question. I run 40:1 w/ Yamalub 2R. I tried some other brands of pre-mix, but I go the least spooge and no fouled plugs w/ Yamalube and my jetting.

165 main, 38 pilot w/ a 1367 needle (set in the middle groove - I think). My jetting is set for the California High Desert areas. My bike starts 3rd kick if I haven't run it for a few weeks, 1st or 2nd thereafter. I get the usual amount of smoke, very little, if any spooge and I haven't fouled a plug since I got the jetting and pre-mix ratio the way it is now. I'm running a Br7 plug as well.

Now, my WR on the other hand, has all free mods and starts 3rd kick after sitting and 1st or 2nd kick thereafter. I guess I just have my stuff set up right! :ride:

 

[abramja]

Kdx250d1

I bought mine a few years ago, actually looking for a 200/220 and ended up with this one. Knew nothing till after, thought it would be the same as the smaller bike. Not at All, except the color. But I like mine. It works for me and my moderate trail riding skills just fine. It has good power, runs great, idles good, and handles the harescramble trails of Indiana just fine. At 5'9'', I'm a little short in the saddle for it, but I like the travel, and usually don't ride over my head which keeps putting both feet down to a minimum. The guy that had it before me just had the motor rebuilt at the local shop. Other than that, the motor is stock, and I have an aftermarket baffle on it. (I have ran the stock some, and feel it has a little more umph with the new baffle. Not sure of the make?) I think it has the stock jetting. In fact, except for the baffle/b pipe?, it is as stock as it can get. I run a 7 plug, due to me putting around with my kids a lot. I would foul 8s and 9s pretty often. I fouled the 7 after running it for a year. I call that OK. It also can be a booger to start. It took me a while to figure out to choke it and not touch the throttle till it starts. Then when it starts, the engine revs to a bazillion rpms, that I regulate with the choke button till it will idle slow. It sputts a little till it gets warm, then away we go. I use Castor 927 oil at 32:1. If I was going to get rid of this, I would need to go to a 250 four stroker to keep up with the torque this thing has. Good luck with yours!

 

[kdxdumb]

I would like to thank everyone for their help, but I sold the bike this weekend. I found out it had a blown headgasket. I now have an 1986 Husqvarna cr500 if anyone knows anything about it.