USD Forks . . . Shim Questions

Questions and comments about converting to beefier forks..
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Jeb
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USD Forks . . . Shim Questions

Post by Jeb »

. . . '98 YZ125 forks! They're 46mm KYBs, similar to the KX125/250 forks of that era . . .

$85 with shipping. I've been bidding here and there, pretty low bids really, waiting for this to happen. Need new seals, got a few scratches . . .

. . . I had searched earlier and didn't find where anyone had tried these yet so there's some unknowns . . .

. . . more later !!
Last edited by Jeb on 06:17 am Feb 04 2007, edited 1 time in total.
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Indawoods
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Post by Indawoods »

Need to compare them to the 98 KX forks to see if they are the same as in triple trees. Fuzzy's 97 WR 250 Triple Trees would not work at all on my KDX.....
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Post by Jeb »

What didn't work?

Before I bid, I looked at the pics on ebay and compared with my KDX triples and couldn't find anything obvious. 'Looks like the steering stop tabs have similar orientation. Just eyeballing, they look similar.

I just looked at yamaha-motor.com drawings comparing 98 yz125 and 97 wr250, not a lot to look at but they look like different triples from what I can tell.

Go here for shots of the forks for comparison and comments

Push come to shove I'll find some KX triples - the fork tubes themselves ARE similar
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Indawoods
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Post by Indawoods »

The stem hole was huge! No way I would ever get the KDX stem to fit....
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Post by kawagumby »

My 03 46mm kx500 forks fit my 99 yz triples exactly and the center TC hole was .001 larger than the kdx stem diameter, so a .004 knurl did the job nicely.
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Post by Jeb »

>|<>QBB<
kawagumby wrote:My 03 46mm kx500 forks fit my 99 yz triples exactly and the center TC hole was .001 larger than the kdx stem diameter, so a .004 knurl did the job nicely.
That's fantastic news, kawa, 'cause the '98 and '99 look the same and have same part numbers for everything I looked at!! Thanks
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Post by Jeb »

I'll need to replace the seals - any recommendations on seal mfgs?
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Post by skipro3 »

Race Tech makes good seals; about $25 a set. They are heavy duty and take about 100 miles or so to break in. That means there's a bit of drag, AKA stiction. That's important to know as stiction is an issue with these forks when it comes time to clamp them down and for tuning them.
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Post by Jeb »

>|<>QBB<
skipro3 wrote:Race Tech makes good seals; about $25 a set. They are heavy duty and take about 100 miles or so to break in. That means there's a bit of drag, AKA stiction. That's important to know as stiction is an issue with these forks when it comes time to clamp them down and for tuning them.
Did some searches on the "stiction" issue and I think I generally understand . . .

adjust torque on clamp bolts to achieve ease in fork travel (handlebar-grab test) and fork returning to position (sort of a hysteresis kind-of-thing). Should be able to torque the bolts to 12 ft-lb or so, if much less I probably have issues with the forks . . .

does that sound about right?

Thanks for bringing this up Ski, I've got a lot to learn.
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Post by canyncarvr »

By rule of KDXRIDER, 12ft/lbs has been found to be on the tight side.

Ten will do.

Makes a BIG difference!

Hint: If you're taking them apart for seals, DO check to make sure the inners aren't bent. 'Ya don't want the 'm0rie effect' to bite you after you have spent more time and $ than is necesary.

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Post by m0rie »

>|<>QBB<
canyncarvr wrote: Hint: If you're taking them apart for seals, DO check to make sure the inners aren't bent. 'Ya don't want the 'm0rie effect' to bite you after you have spent more time and $ than is necesary.
Wow - I feel special that i've got an "effect" named after me...

:mrgreen:

*edit*

For those who have no idea what were talking about this thread should explain it pretty well.

http://www.kdxrider.net/forums/viewtopi ... bent+tubes
1989 KDX 200
2007 TTR-50E
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Post by krazyinski »

I have had good luck with these from http://www.rockymountainatv.com for 69.00

* Pivot Works NEW Fork Kits.
* Kits consist of fork seals, wipers, and upper and lower bushings.
* Just like Pivot Works famous bearing kits these new Fork Kits come with everything needed to do the job the right way, the first
time.
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Post by scheckaet »

I have had good luck with these from http://www.rockymountainatv.com for 69.00

* Pivot Works NEW Fork Kits.
* Kits consist of fork seals, wipers, and upper and lower bushings.
* Just like Pivot Works famous bearing kits these new Fork Kits come with everything needed to do the job the right way, the first
time
That's the one I also used on the good recommendation of krazyinski :wink: .
Everything is pretty easy to remove, clean and re-install.
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Post by Jeb »

Thanks for the replies, guys - 'forks are due here tomorrow and I'm anxious to see how things will work out . . . more later!
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Post by Jeb »

Yep, came in today. 'Got "MX TECH" stickers on the side - don't know if that means a thing about what's inside but it's got me hoping a little - who knows, maybe it's been revalved!!

'Cursory measurements: center-to-center brake caliper mounting holes the same, distance from mid-axle to each mounting hole close enough, and . . . whew, I'm measuring the same stem hole IDs from the bottom of the bottom clamp, I believe that's a good thing!!

Minor nicks/scratches on the outers, not bad at all; inners nice-looking ('cept for the oil - definately needs the seals changed). No stripped bolt holes that I could find. 'Got the oversize bar mounts because it's a aftermarket top clamp - CRAP!! And my new fancy Emig Racing solid bar mount ain't gonna fit - CRAP (guess one of you guys can steal it from me - supposed to work on KDX or KX, confirmed on the KDX). Cheapest route is probably finding some standard size bar mounts.

'Still a bunch to check for fit, but so far the YZ forks are lookin' OK.

Sorry, I 'gotta be boring you guys to tears so I'll clam up, I'm just psyched like you wouldn't believe! (and the wife just wouldn't understand) More later (probably MUCH more!!!).
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Post by stringburner »

You are on a mission. Your KDX is gonna be like a GNCC Works machine by springtime. :partyman: I looked at my inverted foks today. KDX stem is pressed into the RMZ lower clamp, lower bearing is on, shim is in the top clamp, and I'm gonna pick them up this week. I'll post some pics when I get 'em. :grin:
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