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kawagumby

A different solution for obtaining XT fork versatility

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got mine on e-bay from a m/c recycler , 115 bucks with front guards & brackets , axle was a couple bucks more. they were in perfect condition , all yz 125 stuff

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23 hours ago, kawagumby said:

Hi Survivor,

These forks would fit, the upper and lower tubes are identical to the 125's forks.  However, your weight would be best suited to using the 125 forks, which have .41 springs, vs these 250 forks, which if stock, will have .43 springs.  The 250 stock valving is stiffer also...   The 125 combined stock springs' rate is just slightly higher than the stock single XT spring's at .8.

Here's a set you might be interested in : https://www.ebay.com/itm/2001-Yamaha-Yz125-Right-Left-Front-Suspension-Forks-Shocks-Set/223190749841?fits=Year%3A2001|Model%3AYZ125&epid=1028623562&hash=item33f7349291:g:IsUAAOSwH~RbxMqa:rk:48:pf:0

Things to look for when shopping forks include:   no scratches or pits on the lower fork surface,  the bottom compression allen is not rounded, no lumps or discolorations on the upper tubes (can indicated inter-granular corrosion), no broken tabs or stripped threads, the cap nut is not rounded.   Most professional motorcycle recycle businesses are good to deal with, and if there is a problem will accept returns - my experience is they have the cheapest prices and clean the parts too.  If you can get a set with fork guards in decent shape, that'll save another $30-40 also. I've purchased over ten of these forks, and average cost has been about $120 per pair including shipping (but I watch for good deals).

                                                                               

Million Thanks to Kawagumby for all he did to help me (me being a very poor mechanic / :excuseme:) to achieve my goal. He took time to double check my order! :banana:  All in all, it was only +/- $400, it is a pefect description by Kawagumby to achieve such an improvement on the suspension. Thanks again!
 

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On 1/15/2019 at 1:06 PM, kawagumby said:

BTW, the lower triple clamp area wall thickness of the YZ KYB forks is 5.7mm before machining.

kawagumby, could the tube be machined/shaved for that 1.1mm down one inch below the lower clamp instead of the full lenght of the thicker area (the +/-5.7mm) which seems to go a fair way below the lower clamp? Going one inch lower with the 1.1mm shaving would allow to lift it in the tripple clamp and if someone wanted to, keep the full thickness where there is no need to reduce the thickness.. If possible, can you give me the lenght in inches (reference to your YZ fork) from the top of the tube to the "one inch"lower below the lower tripple clamp Thanks again for your expertise and help.  

Edited by Survivor
clarification

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Hi,

Sure, you could limit the machined area.  On my bike, with the forks shortened 3/4",  the top of the fork cap is 11mm above the top of the upper triple clamp.  One inch below the bottom of the lower clamp is about 11 inches below that top of the fork.  (do you like the way I mixed metric and US measurements? I didn't think so...LOL.)    The only thing I would be concerned about in doing that would be the possible creation of concentrated stress - a "stress riser",  but that could likely be avoided by gradually tapering the two diameters together.

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24 minutes ago, kawagumby said:

Hi,

Sure, you could limit the machined area.  On my bike, with the forks shortened 3/4",  the top of the fork cap is 11mm above the top of the upper triple clamp.  One inch below the bottom of the lower clamp is about 11 inches below that top of the fork.  (do you like the way I mixed metric and US measurements? I didn't think so...LOL.)    The only thing I would be concerned about in doing that would be the possible creation of concentrated stress - a "stress riser",  but that could likely be avoided by gradually tapering the two diameters together.

Kawagumby, very good observation ? about the concentrated stress.Thanks for this advice. I guess that a distance of +/- three quarter inch for gradually tapering that 1.1mm would work fine to eliminate most of that stress :thinking:? Do you agree? Also, do you raise 11mm or +/- 7/16" for a rake change for corner reaction or to lower the motorcycle? All my stuff is coming in Ogdensburg, NY next week so it will be exciting to drive there and pick it up. To get this project on going makes me look forward to spring riding :banana: . This gets an old man like me something to talk about :blah: with his friend riders while waiting for the cold and the snow to go away! I am also like you and do mix the Metric, English and even the Decimal system in my hobby challenges. I sincerely appreciate your help :thumbsup:

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1 hour ago, Survivor said:

K? Also, do you raise 11mm or +/- 7/16" for a rake change for corner reaction or to lower the motorcycle?

Raising the forks to that height helped reduce effort during sweeping turns while being centered on the bike.  I would think the fork width transition you suggest would be fine - it would be interesting to see how much measurable fork flex actually occurs while riding...I wonder if there's a video of that somewhere.

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On 1/15/2019 at 1:06 PM, kawagumby said:

BTW, the lower triple clamp area wall thickness of the YZ KYB forks is 5.7mm before machining.

kawagumby, the 2001 YZ forks are on their way to the tuner :banana:. I have followed your tip (in your previous analysis) and got the shaving to be done again to reduce it at 56.03 mm (+/- 0.02 mm precision). I brought it back to the machinist to bring it down as it was not pleasant trying to fit in the clamp  before he brought it down to 56.03 mm. Thanks for mentioning that in your analysis. Trying the tube in the upper and lower clamp saved the day as doing that confirmed the shaving redone to achieve an easier fit (56.03 mm) was worth doing it before reassembling the forks. Now they fit almost the same than the OEM forks on the X Trainer. Maybe just a very tiny bit tighter but no problem at all to bring it up in the upper and lower clamp. A 1.5 mm wedge to make the gap bigger in the clamps also made magic :applause:!  Thanks so much for your constant support :prof:. Can't wait to ride it :ride:

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wow -- after getting a bunch of riding in with the k y b fronts , and adjusting to what I like , this thing is Wonderfull to ride now, unbelievable difference. the ultra slow speed technical riding  , up to way zippy trail riding,is spot on. also did the fox shock rear. transforms the  x t  totally into by far the best ( trail bike ) I ever have ridden.  well worth the expense and hassle ( minor stuff ). .  thanks for the tip

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Posted (edited)

Edit:

nvm. I’ll report back once the whole conversion is done. 

Edited by MateoMatt
Yes, rotors are warped

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forks , wheel & hub assy. , brake rotor , axle , all yz 125 . the caliper is the stock beta. I did have to center the caliper on the rotor , by using stainless washers as shims  on the mounting bolts. mine would drag to , without the shims

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Kawagumby, Thanks for the fork tip.  I finally finished my conversion on my 16 XT. The main question/problem I had was the overall length of the forks.  After removing the preload spacer/rubber bushing (about 1" long) I still needed to shorten the forks another .75". To match the old fork length (about 35.5").  So I made 2 alum spacers 1.75" long put them on the damper rod, under the cap so effectively decrease the overall length of the damper rod by 1.75".  This made the overall total length of the forks the same as the old ones.  I also cut about .75 off the spring.  Still haven't rode it yet, waiting on the rain to stop.  So the main question is how did you shorten the forks/damping rod?  Did you use a .75" spacer or????  Thanks again for the great write up.

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I shortened the forks, but I did not use overall length as the comparative dimension, rather, I used the length of the fork under compression with just the weight of the bike as the basis.  As I recall, it was somewhere around 3/4".  Also, there was no need to cut the springs with that length of shortening (which turned out to be very close, geometry-wise with the .41 yz125 stock springs).  I ended up having the top of the forks level with the triple clamp for best handling and turning.   I did use an internal spacer to shorten the damping rods.

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I had Enzo racing do mine when they revalved. He said he bored out that top metal piece to allow the springs to go higher up in the fork.

 

This was enough to lower the forks an inch from stock, which is what I wanted

 

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