90 kx125 forks on a 250D2?

Questions and comments about converting to beefier forks..
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tha_reids
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90 kx125 forks on a 250D2?

Post by tha_reids »

I own a 92 250. Got a lead today on a 90 kx 125. My friend owns a shop and gave the guy a quote to fix his bike. Way more than its worth. It's sure to end up a parts bike. Maybe mine :wink:

I read a thread that said the 91 kx500 forks are a bolt-on swap for my bike. Maybe the 90 kx 125 is too? Hard to find any info on 250 kdx swaps.
Damn 200-220's!!! :evil:

I know there may not be any kdx 250 knowledge banks in here but does anyone know anything about 90 kx 125 USD forks?

Thanks
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Post by m0rie »

I think they were a one year deal. 41mm USD's if I recall correctly. The real trick would be seeing if the 250 engine could fit in the 125 frame. That would make for some fun... :lol: Do your 250 forks have rebound adjustment?
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tha_reids
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Post by tha_reids »

thanx Morie



No rebound (what the hell was kawi thinking).
My bike is clean, only has 2,000 miles on it. Wouldn't feel right using her for a parts bike. Thats blasphemy! :cry:
Forks on my bike don't feel right to me. There is a lot stiction in the forks.
No sag at all unless I apply front brake and dip forward. Havent serviced them and I'm sure they need it. Would like to know if the springs are stock. (bike had fmf pipe, can but stock jets) :shock:

I need a game plan cuz if not, I will be tempted to throw some springs in when I service them and would be throwing money away.

What to do....what to do....
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Post by radonc73 »

I would say that chances are if they didn't replace the jets they never dove into the front end, but I may be wrong. You may want to recheck the torque on the clamps I read somewhere on here that that will cause alot of striction.
Did you look at the Kawi website to see of the PART numbers are the same? I was wondering this myself but saw on a different site that Eibach has springs that are a little longer if you just want to replace the springs.
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Post by m0rie »

If your current forks don't have a rebound adjustment I wouldn't send a whole lot of time and money on them. Put that money towards a newer set of KX forks. With that being said i'd try to go a little newer than those 90's. 95 and newer had midvalves which can be a good or bad thing depending on who you ask, and 96 have 46mm tubes which provide a pretty big jump in stability.
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Post by tha_reids »

radonc73,
My thoughts on the jets exactly. This bike had a serious spooge issue. I got a service manual with the bike so I did some detective work. I found greasy finger print smudges on the kips valve and fork sections! All over!:shock:
You still running stock setup on your forks? what are your sag numbers front and back? if you don't mind.
I took this bike out for the first time in the end of Nov. 4 days in the high desert. I only had enough time to go thru the topend, new chain, jets, and inspected it for possible mechanical failures. I never checked the suspension settings. I knew the bike sat way to high (tippy toes). Bike did well with the motor changes. First problem, front end didn't take kindly to even the shallowest of ruts. Had to re-aquaint myself with the 'how to plant my foot to keep the front from folding in at 35mph+'. Next we hit some whooptiedoos, no prob. Then we hit some that where endless. At least 100 of em. After 75 or so I had some serious arm and leg pump and had to get off the trail. I felt conquered. Other than that, everything was great.

After I got back I looked at the suspension. Rear sag was only 2"s. I backed it down to 4". I can get both feet down flat footed now :grin:

m0rie,
Thanks for the info on the years with mid-valves. Great to know when making decisions. I'll hold out for a better swap candidate.
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Post by radonc73 »

I am ALOT larger than what the manual suggests I be. Race-tech recommends a .48, ya I am a fat ass. The OEM rear spring is set for a 180lber I weigh about 230-240 depending on my winter weight coming off. :roll: The front by racetechs calc is set for a 75lb rider. That doesn't sound right. I just did the calculator so something is amiss :? I figured with being SO far out of recommendations trying to set sag would be an excercise in futility.
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Post by tha_reids »

Ya, heard they have weak springs (.35?) with a lot of preload (I'm pretending I know what I'm talking about). Too much preload would have a direct impact on front sag (duh). I spend so much time on KDX sites and read so much info on 200-220's that I tend to forget my own 250D specs :roll: The only spec I do recall on a regular basis is that the 250 is king of the KDX's!:mrgreen: Thats why they had such a short production run! Limited Edition baby! :lol:
J/K

I had this theory awhile back. Maybe KYB fork tubes are all the same (or at least some) and I can just swap the internals :grin: Only wish it were that easy.
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Post by radonc73 »

Every KDX 250 owner is special, it takes a certain type person to buy a bike with undersuspended front end with all that power behind it to bottom over most small rocks and ride the hell out of it.
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Post by canyncarvr »

Noticed the sag change from 2-4".

Mentioned this a bit earlier..on a thread that escapes me at the moment. Don't recall reading a response, either.

Anyway...setting the race sag is only 1/2 the equation. After you do that, check the free sag. THAT figure will tell you if the installed shock spring is correct for your weight.

A correct race sag that results in an incorrect free sag results in an incorrectly working suspension.

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Post by tha_reids »

Hey CC,
Free sag checked out at 1".
Fronts my only issue. This is the first bike that has taken me off a trail. First ride I literally split the base of a manzanita in half when I stuffed the bike into one. Sliced my forearm pretty good. Second ride I couldn't keep her pointed straight on a hill climb. Had to let off the throttle to avoid going head up with a rock formation, corrected my line and ended up running out of momentum just feet from the top. I can still feel that one :shock:. It just seems that when it gets extremely choppy and I'm near wide open, it feels extremely unplanted and I end up way to the right.

Probably just need to get the suspension dialed in a bit more and get better acquainted with her nasty habits.
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Post by radonc73 »

I know the feeling, the stock springs are pitiful. I heard from another site for suspension that the closest to MY 93 spring lenght of 506.5 mm is either the 975 series which is 508 mm in length or the 989 series which is 486 mm in length so you would need spacers. I have no idea about the preload and all of that. Ijust wanted to see what was compatable with my suspension. I don't know what your spring free length is but for mine those other springs will work with a little modification like spacesr or someone suggested cutting a few mm. off of the longer one.
Last edited by radonc73 on 02:30 pm Jan 13 2007, edited 1 time in total.
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Post by Indawoods »

Reducing the preload increases the sag which makes the front more planted. Check your preload and report back....
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Post by canyncarvr »

Free sag at 1"

Makes you wonder what the 2" was all about, don't it?

Good luck with the 250 front end. Obviously something is wrong with it. Maybe it was worked on by the same buy that set the race sag to 2".

(or maybe he weighed 340#)

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Post by tha_reids »

Ya, most of the questions can only be answered with disassembly.
Ride report, maybe in a week or two. Got the mx fender being fitted and a pipe guard being glassed at the moment. After those I'll tear apart the front end.

History: Bike was purchased in 93 by a 6'4" 340lb corrections officer named Lil' Bubba. 1800 miles later the bike was sold to a gentleman in Sac. He bought his 2 kids and himself a bike and gear just to turn around and sell them off a month later. :doh: When asked about the bikes performance upgrades he stated the obvious ,"(beer swig) There is the FMF pipe, can, and something to do the forks but can't recall what exactly (another beer swig). Taken with a grain of salt. Test rode her up the street ran out of gas. He put about a quart of gas in (I thought that was odd). Broke him off 8 crisp ones and the bike was mine. When I filled the tank the first time I found a small leak from behind the rear bracket. Nothing my hot air welder couldn't handle.

One of my biggest reasons for buying this bike is that it belongs to my era. My first bike was bought in 81.

Need to go shopping with the lil' wifey :neutral:
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