kdx250 91-94 info (us bikes)

[JJRace]

Figured some good info on the bikes would be a great sticky. Here is the info I have on them from my experience with my own:

The KDX250 is a lot like the WR250 and RM250 of the years. They are an eduro model MX bike from the factory. They suffer from poor jetting, engine performance and suspension. The factory added a XR style rear change adjuster, kick stand, larger tank, Wide Ratio tranny and lighting stator to the KX motor make up the mods to make it a KDX model.

To get the bike into peak performance, you will have to start with the motor, then jetting, then suspension.

Where to start your modifications:

]freebies:

1) Remove the airbox snorkle from the lid and cut the lid open to maximize air volume intake.

2) put the needle in the second notch from the top (carb will still be jetted to rich)

3) set the sag on the rear suspension

now you will find that the bike still has carb issues, performance issues and suspension issues. So you will be putting some money into the bike to make it into what I can become.

]money mods:

1) KX250 thin headgasketfrom 1988 (.26 vs .46 in thickness)

2) Rejet the carb -- 38 slow, 158 main, #6 slide, R1367 needle 3rd clip. This will bring the bike closer to the KX spec.

** I ran 50:1 amsoil, so jet according to altitude and mixture.

3) aftermarket pipe (anything is better than stock)

4) aftermarket silencer/SA

5) aftermarket reeds (Vforce recommended)

6) NGK Iridium IX plug (BR9EIX)

7) install stiffer fork springs (at least .38s from a KLX300) with new 2.5 or 5w oil

8) port the cylinder[/size]

9) have the cylinder head squish redone[/size]

That will get the bike's motor and jetting where it should be. It will be a different bike all together with those mods. Be sure that you inspect the clearances and replace internal parts as needed since these are old and used bikes. Also inspect the power valves, clean them and be sure they are timed properly.

The suspension will still be hurting. I found a set of 43mm forks off a early 90s KX250 and rebuilt them, then installed them on the bike with the KX front wheel. You will lose the odometer but with aftermarket units like the trailtech setups, you can easily upgrade there. The KX front suspension is a must do upgrade for anything faster than 1st gear on these bikes! For the rear, you can simply revalve and respring the stock shock.

Where parts come from:

Keep in mind that the 91-94 KDX250 was built off the 88-91 KX250 bike mainly. There are some differences between the bikes, but if you get stuck trying to find a part, be sure to cross reference those year bikes first. There are also a lot of bearing and clutch parts used of the KX500s of the same years.

-Brake Pads: KX125/250/500 89-93. pads and rotors are the same as the 89-02 KX125/250/500 for the 91-94 kdx250. So you can get the ceramic pads and wave rotors. Brake lines seem to be different though same with the Master cylinders. You can run the KX front and rear SS aftermarket brake lines without issue. A great upgrade is a 02+ CR/CRF honda front master cylinder with lever. The 07+ have the linkage for even better performance.

-Steering head stem bearings list the same for the 80-91 KX250 and KLX250 94-96

-For the Fork seals, the 88/91-95 KX250, KLX250/300 fork seals list the same as the KDX250 units (43mm units). The stock is a 43mm ID x 55mm OD x 9.5mm height. you can run the 10.5/11mm tall seals for beatter sealing.

-Fork gaurds is the same as the KLX250/300. You can run the 90-93 KX units also, but they offer no side protection to the forks

-Rear brake holder/bracket -- same as 89-94 KDX200. Use this for the rear shark fins & scotts gaurd

-Front Forks: Kayaba. .35 kg for 92-94, .34kg for 91. 43mm inverted. (similar forks as the KLX 250/300 bikes). compression only adjustment and very poor forks for anything but slow speed work.

-Rear shock: 4.8kg for 92-94, 5.0kg for the 91. Spring same for 88-02 KX and 89-94 kdx200. Eibach 996 series

-Sprockets seem to be a KX/KDX thing. No differences there.

-aftermarket Chain rollers = Small

-Chain Guides: 88-96 KX 250/500, KDX200

-Reeds are the same as the KX500 units in FMF. Boysen same as 89-96 KX250. Mototassinari use the KX500 Vforce kit.

-Lower shock bearing/seals is the same a 88-01 KX500

-Unitrak bearings are the same as a 88-01 KX500

-Rear swing arm slider is the same as the 94 kdx200 , 89-01 KX500

-Rear mudflap is the same as the kx250 (90-91)

-Looks like the seats are a bit different, but a cover would most likely fit both From a 91-94 250 or 89-01 KX500.

-Clutch: 89-01 KX500, 88-91 KX250

-Clutch cable 90-91 KX250

- Throttle Cable : 88-91 KX250, 88-02 KX500

-Top End gasket, same for 88-91 KX250 (stock thin head gasket .26")

-Piston Needle Bearing 74-02

-Connecting Rod 78-02 KX250

-Piston & rings KX250 90-91

-rear bearings wheel bearings: Timken 104 series bearings. You can pick them up at any autoparts store.

1986-2002 KX125/KX 125/KX250/KX 250 and KX500/KX 500, 1989-2002 KDX200/KDX 200/KDX220/KDX 220; 1991-94 KDX250/KDX 250; 1993-96 KLX650A/KLX650R/KLX650/KLX 650; plus the 1983-84 KL250C/KLR

-Front bearings:

Timken 202 series bearings. You can pick them up at any autoparts store.

KAWASAKI: 1983-83 KX125/KX 125; 1968-70 F3 175; 1983-96 KDX200/KDX 200 1969-70 F4 250; 1971-72 F8 250; 1973-75 F11 250;1982-84 and 1991-94 KDX250/KDX 250; 1994-95 KLX250D/KLX250R/KLX250/KLX 250; 1970-75 F5/F9 350; 1993 KLX650A/KLX650R/KLX650/KLX 650; 1993-96 KLX650C.

For the plastic, you can easily run KX front fenders and number plates. The side plates and radiator scoops are KDX250 specific. I used a 1990 KX250 rear fender for a MX look with minor trimming.

Edited February 12, 2012 by JJRace

[argclh6670]

JJ, excellent info, i just come across a 92, runs pretty good, does seem to be filthy rich thru out. IT needs a few parts but as ium finding out they are not very plentiful (kdx parts) so ur info is such a find! thanks again my man.

[JJRace]

Just remember the more KX you make the bike, the better it runs and handles. Thus the forks, head gasket and the jetting specs from a similar year KX

[argclh6670]

Hey JJ, i got a front end off of 96 kx250, everything but the front brake resevoir/lever/line.

ive been looking at possibly swapping them out, everything seems tobe the same cept the top bearing and stem @ the top. So, just to keep me smart cant i just have the stems pressed out and then swapped in triples? If its possible i think this would prolly be a huge improvment? please let me know what you think.

Also, im in the process of changing the jets, i dont have nor have resources for a #6 slide (it has a 7) this should work still right? im sorry if im asking some lame questions, im just not where i need to be knowledge wise on jetting an such.

1 more, i know in ur thread you mention a 1367 needle. Which is leaner the 1367 or a 1468 which i have on tap. and will in ur mind the 1468 be okay.

Edited January 4, 2013 by argclh6670

[Chuck671]

Hi Guys,

Maybe your KDX 250 gurus know...I've got an 89 KX 250 (same base engine) that needs a new clutch basket (getting notched). Used the parts-cross reference that's stickied (very cool...merci Jeekins!) and found that all year KDX 250 baskets share the same part number...not too many, but have seen a few of each (more KDX than KX) baskets on eBay.

But...there are two different baskets that are pictured...some with notches in the top of the basket fingers, some flush across the top. Were there more than one style of basket for that bike that Kawasaki made (w/the same part number) or do the eBay folks have the parts mixed up? If there was only one type, was it notched or flush fingers?

Saw in your note that the KX 500 shared the same basket...I hadn't thought to cross-reference that, but same basket? Don't see my/our bike nor KX 500 listed on Wiseco (well, Pro-X, but not the forged one), Hinson or Barnett for baskets.

Thus far, I've found that most of the eBayers have the accurate year on the parts I've ordered (not tons, but enough 80's vintage stuff), so it's a little disconcerting to see more than one style basket and start shelling out the coin! Any input appreciated.

Thanks and best wishes w/your bikes!

Chuck

[JJRace]

Jetting, you need that leaner slide. Check out RB designs in oregon. he can cut the slide for cheaper than a new one. Also check Ebay for a early 90s KX250 carb and it will have what you want. I know when I had the bike, I looked at the KX250 jetting specs and started there. took about 4 rides to get it completely dialed in and those were my settings. Altitude and temp may have slide adjustments on the pilot/main, but that should be your ticket.

For the triples, yes swap the steering stems. I think that should be a simple swap. You can measure the lower clamp to make sure both are the same diameter for the stem. I believe that is what I ended up doing also.

For the clutch and basket, I know I looked a LOT of the info up on LightSpeed and crossed the OEM part numbers. Aftermarket stuff really has forgotten about the KX500s and the KDX250s. So a little looking and investigating will get you answers. For the top of the basket fingers, it doesnt matter. I believe that is a weight saving notch there. A plate definately doesnt go in there!

[WReTICKET]

Excellent info! I just picked up an 89 kdx 200 for my kid, from the original owner!!! nice little bike. Front end needs to be worked for sure, too soft, for his agressive style. This bike is pretty much stock, except for new rubber and bars. One question though, any advise on a slip on silencers, that is truly silent, without loosing any power? The neighbors would appreciate it! Thanks Mark

[SS109]

Excellent info! I just picked up an 89 kdx 200 for my kid, from the original owner!!! nice little bike. Front end needs to be worked for sure, too soft, for his agressive style. This bike is pretty much stock, except for new rubber and bars. One question though, any advise on a slip on silencers, that is truly silent, without loosing any power? The neighbors would appreciate it! Thanks Mark

The '89-'94 factory silencer is the best for being quiet.

[KDXGarage]

"Just swapping stems" will ABSOLUTELY NOT work on a 1996 KX250. Press the stems out and grab your measuring device. WOW!! I did. You can, too!

[argclh6670]

"Just swapping stems" will ABSOLUTELY NOT work on a 1996 KX250. Press the stems out and grab your measuring device. WOW!! I did. You can, too!

WHY NOT? WHATS THE DIFF. OTHER THAN THE KX STEM BEING ALIL LARGER IN DIAMETER AT TOP BEARING/CLAMP

[rigidboy69]

Great information.  I have a 91 KDX 250 and looking for a rear wheel.  Does a KX rear hub from the same model year have the same offset?

[bigharty]

this info is gold mate, ive just been given a 91 kdx 250, it goes ok but its as rich as Donald trump. im keen on doing the carby & head gasket mods and ive found all the parts ill need to complete it on line.

im also keen on putting a pro circuit pipe and silencer on it and im pretty sure (if ive absorbed all the above information correctly) that part no PK89250P is the correct pipe and the correct silencer is part no  SK89200D-304 can somebody please confirm this for me please?

thanks

nick

[hoferjeremy123]

I have a 1991 kx250 and cant find a fmf exhaust pipe what other year of a kx would fit?

[rigidboy69]

I have a 1991 kx250 and cant find a fmf exhaust pipe what other year of a kx would fit?

[rigidboy69]

I have a 1991 kx250 and cant find a fmf exhaust pipe what other year of a kx would fit?