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KYB PSF on KTM 350sxf

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Recently picked up some 2103 KX450f fork off of ebay to install on my 350sxf. The conversion was pretty straightforward.


 


-shim lower triple clamp


-machine axle spacers/bearing adapters for KTM wheel


-modify KTM caliper bracket and machine an additional bracket for lower mounting hole


-cut off KX fork guard mounting post from lugs and weld on new post to for KTM guards


 


One thing I noticed right away is the weight difference between the two forks. I'm not sure if the WP forks are heavier then the conventional spring KYB or Showa forks, but the weight saving was nearly 3lbs. The feel of the fork is also different then my WP's.


 


I only have about 30 minutes of time since the conversion. On the forks I had to go full soft on the rebound and basically full stiff on the compression, and slow the shock rebound down to get it decent. I wanted to get a baseline feel for the fork before digging into them. I now have the forks apart and noticed that they have already been revalved. After contacting the seller he said they were setup for a 150lbs rider, which is a good bit lighter then the 210lbs i weigh.  Anyways just thought I'd share the conversion.



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Awsome job but machining off the guard mounts is a serious job , I would use white or black kx guards ? Is the fork length and offset the same ?

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Awsome job but machining off the guard mounts is a serious job , I would use white or black kx guards ? Is the fork length and offset the same ?

 

 

I had considered using the KX fork guards but I think the KTM guard does a better job protecting the lower leg, plus I like the stock/factory appearance. Using the KX guards would've simplify the conversion. Another option is to use the PSF forks from a Honda CRF450r. The KTM fork guards are a direct bolt-on for those.  

 

Overall fork length is the same but the lug offset is not. There is approximately a 2mm lug offset difference, with the KYBs being the shorter one (KYB 33mm, WP 35mm) I'm not sure what the lug offset is on the Honda.

 

Currently I'm waiting on shims, but hopefully I will get some more seat time on it this weekend.

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Are you pulling the logs off to weld the ktm fok guard mounting points?

Reason I ask is I am pretty sure there is an oring on the tubes where they thread into the lugs.

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Are you pulling the logs off to weld the ktm fok guard mounting points?

Reason I ask is I am pretty sure there is an oring on the tubes where they thread into the lugs.

 

I left the lugs on the forks. There is so much aluminum mass there, that I would just do a small weld, cool, weld, cool. etc... Time consuming to do it this way but it keeps overall heat input to a minimum.

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Recently picked up some 2103 KX450f fork off of ebay to install on my 350sxf. The conversion was pretty straightforward.

 

-shim lower triple clamp

-machine axle spacers/bearing adapters for KTM wheel

-modify KTM caliper bracket and machine an additional bracket for lower mounting hole

-cut off KX fork guard mounting post from lugs and weld on new post to for KTM guards

 

One thing I noticed right away is the weight difference between the two forks. I'm not sure if the WP forks are heavier then the conventional spring KYB or Showa forks, but the weight saving was nearly 3lbs. The feel of the fork is also different then my WP's.

 

I only have about 30 minutes of time since the conversion. On the forks I had to go full soft on the rebound and basically full stiff on the compression, and slow the shock rebound down to get it decent. I wanted to get a baseline feel for the fork before digging into them. I now have the forks apart and noticed that they have already been revalved. After contacting the seller he said they were setup for a 150lbs rider, which is a good bit lighter then the 210lbs i weigh.  Anyways just thought I'd share the conversion.

 

 

Sweet project and nice machine work!

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or swap lugs over.

I think some of the complaints come from the size of the axle lugs( too beefy and stiff) , so it makes sense when swapping forks to keep the original lugs

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How about a ride review with the new legs?

 

 Waiting on some shims at the moment, but I'll update as soon as I take them out again.

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How do you like the bladder conversion?

 

When I got my shock revalved I asked about it but the tuner did not really encourage using one.  Instead he insisted on a low friction piston ring.  Im really happy with my setup, just curious if I am missing any benefits of the bladder.

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On the bladder conversion, it was just something that was recommended for easier servicing. I've thought of converting it back to the piston reservoir just to see if there is a difference in the shock performance. Maybe I'll switch it back over the winter. Who did you have setup your suspension?

Edited by Force_Fed

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Ride JBI did my suspension.  The shock got a low friction piston ring and speed sensitive check valve.  On the forks I had one of the first production JBI Pro Perches installed along with revalving.  The bike is kick ass now.

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Nice job on the conversion,  I fitted 2012 kyb SSS forks from a yz250f onto my 350xcf-w, using shims and yamaha front wheel and brake setup.  I just had to machine wheel spacers since the ktm clamps hold the forks ~2mm closer together than the Yamaha's.  it was a pretty easy conversion.

 

my problem ended up being the overall length of the kyb was longer than the wp, and the offsett of the kyb was ~5mm closer than the wp lugs. 

 

We ended up taking the KYB cartridges out and retro fitting inside a set of wp twin chamber tubes.  the cartridge actually threads right into the wp tubes.  the cartridge had to be shortened ~15mm using a spacer and the bottoming cones and base valve bolt needed some machining. 

 

They work VERY well in my rocky single track!  They are slid up 10mm in the clamps to match my shorted shock in the rear (6mm spacer)

 

 

 

 

 

 

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Just a quick update. I only got a couple of rides on them, trying to get the valving sorted out (too soft and slow rebound) before winter came. Over the winter I had the tubes coated and got new bushings, seals and some more shims. I finally chance to ride it again yesterday after the last valving changes and I'm finally pretty happy with them.

 

      
 

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