Fiirst real ride of the kdx

[mercenary223]

So I took the 91 kdx200 I purchased a few months back upto walker valley orv park here in washington today. I had a experience to say the least. I weight aprox 235 pounds with gear on and I am assuming the suspension is all stock. When in 4th or 5th gear anytime I would go over a bump the bike would flout and wobble up and down due to my fat ass overworking the suspension. I kept bottoming out the rear over any bump over a foot deep and in one instance the rear rebounded so bad it came up and the seat hit my ass and I almost went over as I staired at the front tire. I bottomed out on a rock I was going over and this made me tip it over. Then the fun begins I was riding with my uncle thank god and told him after 3 hours of riding logging roads and pretty good trails I was running low on fuel. Him being the smart one says your fine as he has. Desert tank I say ok and continue on. 20 minutes later I have to put the reserve on and at this point we are lost and going up a steep rocky trail. I make it up about a half mile and that's all she wrote out of gas. So I coast down the hilly trail and wreck from going to fast trying to keep momentum up. So two hours later we are back to a main road and he goes and gets a litre bottle of fuel and gets us to the truck..

So can you make this suspension work a lot better and way less boaty with upgrades to the stock stuff. This was the scariest bike at high speeds I've ever been on. As far as power goes the bike ran awesome and was perfect for my less then talented riding skill I need to figure out how to idle it up a little wants to die when clutch is puled in other then that I love the power delivery. Is there any other back shocks that bolt right up to 1991 kdx. Thanks for your time guys and there were a couple guys on ktms that said the kdx was a great bike tried and tested they said felt good after hearing some of the guys with bad stories of people looking down on them.

[Julien D]

First off you'll need to re-spring it front and rear for your weight. See FRP offroad or ractech for spring rates. Racetech recommends them a little stiffer than FRP. You might need to rebuild the forks and shock as well, if they are bottoming that easily. Set the sag properly in the rear, and that will help immensely. You also have compression clickers on the front you can adjust, and rebound and compression on the rear shock.

[David_L6]

Re-building your suspension with the correct spring rates for your weight will help you a lot. MX-Tech ( http://www.mx-tech.com/ ) has a spring rate calculator.

Don't forget to check all the linkage and swingarm bearings. I've found the linkage to be the least maintained parts on the used bikes that I've bought.

The first thing I do with a new (or new to me) bike is go completely through the suspension. It doesn't matter what else you do to the bike if you can't stay on it.

[OLHILLBILLY]

Yes, check those swingarm and linkage bearings. The swingarm bearings were the only ones I didn't have to replace on my '04. If they've never been done, I can imagine the condition of them on a '91.

[mercenary223]

Thanks guys I checked frp and racetech. The frp is softer then the racetech which spring chart should I use I don't jump more then 3 or 4 feet in the air tops and I don't go looking for jumps I just want a good trail setup do you reccommend the softer or harder side thanks. Also you guys were right the rear shock bushings are shot and front left fork tube is leaking to be expected with a bike this old. Also where is the idle adjustment on the carb I see a big screw on the carb but when I turned it a couple urns both directions it didn't effect anything so I put it back guessing it was a air/fuel screw. Is this a carb you turn the choke one direction or the next to adjust thanks for your help guys

[David_L6]

Check MX-Tech for spring rate (the link I posted above). They are probably in between FRP (on the soft side) and Racetech (leans more toward supercross stuff). If I were strictly trail riding and going to choose between FRP and Racetech recommended rates, I'd go with FRP. Remember, you choose your springs according to your weight and the valving according to your experience, where you ride, how you ride... (trails, enduro, MX, SX, etc....).

Sorry, but I can't help you with the carb on that bike. I'm sure someone here can though.

[OLHILLBILLY]

Idle adjustment is the larger screw with the gnurled head. The air screw requires a flat head screwdriver and is right over the float bowl surface. Here's a parts blow-up of your carb..
http://fiche.ronayers.com/Index.cfm/Mod ... r%281/2%29
16021 is your idle adjuster screw.. 16014 is your air screw.
Is your throttle cable adjusted too tight and holding it open maybe. I've seen it happen, people without a clue using the throttle cable adjusters to "set" the idle.
How is it idleing now? Too fast/too slow/alright?

P.S.. I used Race Tech .44s in my forks with 8-9mm of preload. I weigh 200lbs without gear, ride in the rocks, roots, and tight woods here in the Ozarks, and they seem to be just sufficient,, barely.
But I'm not familiar enough with the older models to know if there might not be some differences in the forks' internals from the '95-up version.

[mercenary223]

Thanks guys. Soon as I start the bike it idles fine but after it gets good and warmed up it idles real low whenever I would pull the clutch around obsticles it would want to die or die. Just a couple hundred rpms off

[OLHILLBILLY]

Take the idle screw out and make sure it's not broke or something strange like that. Count the turns on the way out, run it back in to where you started at plus a couple of more, start the bike and turn it in some more until it picks up the idle to where you want it.

[Indawoods]

When adjusting the idle... you have to keep blipping the throttle so that the slide sits on top of the adjuster...