1990 KDX

Questions and comments about converting to beefier forks..
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KDXohio
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1990 KDX

Post by KDXohio »

My first post!
Not as much information on the 89-94 model conversions. I have a 1990 kdx200 looking to do the kx fork conversion. I found a front end from a 91 kx125 locally for 90$ forks, tripples, axle, front wheel everything but the caliper. From the research I've been trying to do it all looks like the 89-92 125 tripples are a direct bolt on.

KDX lower bearing p# 92116-1008
KX lower bearing p# 92116-1008
KDX Upper bearing p# 92047-017
KX Upper bearing p# 92047-017

So what im looking for is input from anyone and everyone I know most of you will say not to buy 20 year old forks but theyre better than stock and cheap so why not?

Oh and I will rebuild them that's not an issue

And my last question is since everyone would prefer newer forks will any other forks slide up in the 91 kx125 tripples?


Thanks in advance
1990 KDX200 FMF Fatty, Answer VFC silencer, VForce 3 Cage, Wiseco Piston, KX125-J series KYB USD fork conversion, Race tech goldvalves, J series front brake assembly, air-box snorkel removed, Acerbis Headlight, KX450F Front fender, Pro Taper RM bend bars, ASV front Brake lever, MSR Clutch perch and lever, RB Head mod, 36mm PWK carb, Trail Tech Kickstand.
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Re: 1990 KDX

Post by KDXGarage »

1991 is the last year for direct swap KX125 and KX250. MAKE SURE it is 1991 and not newer.

I say go for it. $90 for all that sounds good. Get on ebay and buy a complete front brake system from a 1991.

1991 - 1995 KX125/KX250 and 1991 - 1996 KX500 tubes will all fit.

The 1991 clamps have more offset than 1992 - 1995 KX125/KX250. (a little slower turning)

I don't have measurements to compare vs. each other or KDX.



...and first thing last...congratulations on the post. :grin:
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Re: 1990 KDX

Post by KDXohio »

Awesome thanks for the reply!

OK so I've got more info I found out its an 89 triple and 92 kx250 forks so now I'm not sure the forks will fit the triple clamp he seems to think they do?

Anyone know if the outer tube has the same clamp dimensions as the 91-89
1990 KDX200 FMF Fatty, Answer VFC silencer, VForce 3 Cage, Wiseco Piston, KX125-J series KYB USD fork conversion, Race tech goldvalves, J series front brake assembly, air-box snorkel removed, Acerbis Headlight, KX450F Front fender, Pro Taper RM bend bars, ASV front Brake lever, MSR Clutch perch and lever, RB Head mod, 36mm PWK carb, Trail Tech Kickstand.
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Re: 1990 KDX

Post by KDXGarage »

No way a 1989 convntional (46mm) clamp holds a 1992 USD forktube.
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Re: 1990 KDX

Post by KDXohio »

oh my bad I didn't realize 89 had conventional still. He's thinking the wrong year then the clamp is either 90, 91. Will the 92 forks fit those two years?
1990 KDX200 FMF Fatty, Answer VFC silencer, VForce 3 Cage, Wiseco Piston, KX125-J series KYB USD fork conversion, Race tech goldvalves, J series front brake assembly, air-box snorkel removed, Acerbis Headlight, KX450F Front fender, Pro Taper RM bend bars, ASV front Brake lever, MSR Clutch perch and lever, RB Head mod, 36mm PWK carb, Trail Tech Kickstand.
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Re: 1990 KDX

Post by KDXohio »

I dug up some part numbers the outer tubes changed from 91 to 92 how they changed I don't know but the caps in the two outer tubes stayed the same from 91-92 so I think its fairly safe to assume the upper clamp surface will be the same diameter (of course ill measure everything before i buy) so the question is whether or not the lower clamp surfaces were the same. It's a 2 hour drive for me to get the parts so Im not ready to make the drive until Ive worked through most of the details.
1990 KDX200 FMF Fatty, Answer VFC silencer, VForce 3 Cage, Wiseco Piston, KX125-J series KYB USD fork conversion, Race tech goldvalves, J series front brake assembly, air-box snorkel removed, Acerbis Headlight, KX450F Front fender, Pro Taper RM bend bars, ASV front Brake lever, MSR Clutch perch and lever, RB Head mod, 36mm PWK carb, Trail Tech Kickstand.
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Re: 1990 KDX

Post by KDXohio »

Oh and if anyone needs them here are the diameters on my 99 kx125 forks
upper clamp outer tube 54.75mm
lower clamp outer tube 58.30mm
Inner tube 46mm
1990 KDX200 FMF Fatty, Answer VFC silencer, VForce 3 Cage, Wiseco Piston, KX125-J series KYB USD fork conversion, Race tech goldvalves, J series front brake assembly, air-box snorkel removed, Acerbis Headlight, KX450F Front fender, Pro Taper RM bend bars, ASV front Brake lever, MSR Clutch perch and lever, RB Head mod, 36mm PWK carb, Trail Tech Kickstand.
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Re: 1990 KDX

Post by KDXGarage »

1990 has 41mm inner tubes, with correspondingly smaller triple clamps.

1991 clamps will hold the 1992 forks, just at a different offset.
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Re: 1990 KDX

Post by KDXohio »

Awesome thank you that's exactly what I needed they should be 91 clamps then 92 forks, wheel, and axle. and I sniped a front caliper,line, and master for 15$ on the ebay!

Thanks for all your help
1990 KDX200 FMF Fatty, Answer VFC silencer, VForce 3 Cage, Wiseco Piston, KX125-J series KYB USD fork conversion, Race tech goldvalves, J series front brake assembly, air-box snorkel removed, Acerbis Headlight, KX450F Front fender, Pro Taper RM bend bars, ASV front Brake lever, MSR Clutch perch and lever, RB Head mod, 36mm PWK carb, Trail Tech Kickstand.
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Re: 1990 KDX

Post by KDXGarage »

You're welcome.
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Re: 1990 KDX

Post by KDXohio »

*UPDATE I picked up everything yesterday unfortunately the triple is from a kx125j not an H model also judging by the fork caps or (fork spring seats) the forks are 93+ as they changed seats in 93 oh well I ordered a 91 125 triple as i'm trying to keep my whole stock assembly as one unit.

On a good note I tore the forks completely down and cleaned every inch of them and to my surprise

<UL>
<LI>They were full of oil.
<LI>They were not leaking.
<LI>Seals and wipers were in extremely good condition almost like new.
<LI>The bushings show no wear can still clearly see a p# etched in one.
<LI>Found one issue in one fork the long rebound dampening adjuster rod was slightly bent (most like from a previous rebuild looked like something fell on it) I was able to carefully straighten it and all seems well ill probably replace it in the future as its only 20$.
</UL>

Needless to say Ill be putting them back together with some 5wt or KAYABA O1.
1990 KDX200 FMF Fatty, Answer VFC silencer, VForce 3 Cage, Wiseco Piston, KX125-J series KYB USD fork conversion, Race tech goldvalves, J series front brake assembly, air-box snorkel removed, Acerbis Headlight, KX450F Front fender, Pro Taper RM bend bars, ASV front Brake lever, MSR Clutch perch and lever, RB Head mod, 36mm PWK carb, Trail Tech Kickstand.
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Re: 1990 KDX

Post by KDXGarage »

GOOD JOB!
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93 KYB forks on KDX200 E series

Post by KDXohio »

Well for anyone else running the early KYBs (probably the same on all except the twin chamber forks) my fork springs had worn pieces off of the plastic spring guide on closer inspection of my pistons/shim stacks I realized there were pieces of plastic under the first shim on both the compression and rebound. After I disassembled them I found pieces lodge in the pistons themselves. I can't figure out how to upload pictures but I did take a couple for when I do figure it out.

Jason I saw you had these forks from a post you had in 04 did you ever have this problem?
1990 KDX200 FMF Fatty, Answer VFC silencer, VForce 3 Cage, Wiseco Piston, KX125-J series KYB USD fork conversion, Race tech goldvalves, J series front brake assembly, air-box snorkel removed, Acerbis Headlight, KX450F Front fender, Pro Taper RM bend bars, ASV front Brake lever, MSR Clutch perch and lever, RB Head mod, 36mm PWK carb, Trail Tech Kickstand.
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1990 KDX

Post by KDXohio »

Here's a good picture of the rebound piston with all the plastic still in it I had to dig those pieces out they were very stuck!

Image
1990 KDX200 FMF Fatty, Answer VFC silencer, VForce 3 Cage, Wiseco Piston, KX125-J series KYB USD fork conversion, Race tech goldvalves, J series front brake assembly, air-box snorkel removed, Acerbis Headlight, KX450F Front fender, Pro Taper RM bend bars, ASV front Brake lever, MSR Clutch perch and lever, RB Head mod, 36mm PWK carb, Trail Tech Kickstand.
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Re: 1990 KDX

Post by KDXGarage »

Hi. I did post a picture showing a chip between a piston port and the shim. I don't know if it is still shown. There was also a picture of grey, slimy oil, with mention of "this is why a thorough inspection an cleaning is needed." Something like that, maybe a "don't do a dump and fill" comment.

I want to say mine was from thin PVC used as a fork spring spacer, chipping off.
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Re: 1990 KDX

Post by KDXohio »

Well I got the clamp and the caliper today. And unfortunately these forks don't fit the 1990 clamp the clamp is too small so back to the drawing board
1990 KDX200 FMF Fatty, Answer VFC silencer, VForce 3 Cage, Wiseco Piston, KX125-J series KYB USD fork conversion, Race tech goldvalves, J series front brake assembly, air-box snorkel removed, Acerbis Headlight, KX450F Front fender, Pro Taper RM bend bars, ASV front Brake lever, MSR Clutch perch and lever, RB Head mod, 36mm PWK carb, Trail Tech Kickstand.
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Re: 1990 KDX

Post by KDXGarage »

Jason wrote:1990 has 41mm inner tubes, with correspondingly smaller triple clamps.

1991 clamps will hold the 1992 forks, just at a different offset.

OOOPS. :blink:
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Re: 1990 KDX

Post by KDXohio »

Jason wrote:
Jason wrote:OOOPS. :blink:

Yep read twice order once! Well since the cheapest 91 clamp I can find is 46$ Ill press the stem out of the 90 into the 93 and voila! Ill still have a complete stock E series setup and a complete J series at least the calipers right hopefully
1990 KDX200 FMF Fatty, Answer VFC silencer, VForce 3 Cage, Wiseco Piston, KX125-J series KYB USD fork conversion, Race tech goldvalves, J series front brake assembly, air-box snorkel removed, Acerbis Headlight, KX450F Front fender, Pro Taper RM bend bars, ASV front Brake lever, MSR Clutch perch and lever, RB Head mod, 36mm PWK carb, Trail Tech Kickstand.
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Wrong brake

Post by KDXohio »

So I spoke too soon looks like ive again screwed myself my caliper does not fit so now Im going to sit down and ask some more questions before I waste more money Im not going to tell you the year brake system I ordered as it will just add insult to injury so heres my question the forks seem to be 92-93 so what years brakes will fit?
1990 KDX200 FMF Fatty, Answer VFC silencer, VForce 3 Cage, Wiseco Piston, KX125-J series KYB USD fork conversion, Race tech goldvalves, J series front brake assembly, air-box snorkel removed, Acerbis Headlight, KX450F Front fender, Pro Taper RM bend bars, ASV front Brake lever, MSR Clutch perch and lever, RB Head mod, 36mm PWK carb, Trail Tech Kickstand.
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1990 KDX

Post by rbates9 »

I have a set of 01 KX125 forks with triples and brakes I am looking to sell. I might even be able to round up an axle and a hub but I know the wheel is bad. If your interested.
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