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2003 XR100 conversion with 2005 CR85 expert suspension

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I"m about to start a project Xr100 with 2005 CR85 expert suspension, swingarm, disc brakes and the whole thing. This is going to be done for sure I have complete access to welding, machine shop, water jet, laser you name it. Looking for some insight from anybody that's done this to a Xr/CRF frame. I'm using the XR frame not the Cr frame because my plan is to keep as much of the CRF look as possible. Thanks in advance.

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The front end is a pretty straight forward affair. Nothing too complicated there.

The shock will require moving the upper mount I'd imagine, again nothing super complicated if you can weld.

The swingarm may be interesting. Have you measured up the differences in the swingarm pivot?

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Thanks for the response. No not yet just picked up all the 85 stuff a couple days ago but haven't got in to it yet.

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You'll have to pull the steering stem out of the XR and weld it into the CR triple tree.

As ACDNate mentioned, the rear will be interesting to be sure: Without knowing all of the geometry of the CR85's swingarm...

I converted my XR100 to early CR80 suspension. I swapped out the CR shock for an XR200R unit (clickers, higher spring rate etc.). The CR shock was 14" eyelet to eyelet, the XR200R shock is 13 5/8". I moved the XR100R upper shock mount as high as possible while still being able to use the stock mounting hardware at the top shock mount.

XR200vsCR80rearshock021.jpg

As you can see, the swingarm angle is fairly extreme. Note the bolt for the upper shock mount is barely visible. To have the upper shock mount be higher and still be a nut/bolt mount would require a serious bit of rework to the seat/frame. I have since de-stroked the XR200R shock 3/16" of an inch, resulting in a 1" drop in seat height (still 4" over stock with 14"/17" wheels). I was able to bolt up the CR80 link to the stock XR100 location (see pic), just had to fab a spacer to keep the link from wandering.

The late model CR85 rear shock is (going from memory) 17" eyelet to eyelet; most of the increased length seems to be in the lower portion of the shock; this may be due to changes in the length / position of the link etc. Can't go up with shock mount, so you must go down with link. I would assume you are into at least fabbing a link mount on the XR frame, if not more.

The swingarm pivot bolt diameter for the CR85 is larger diameter than the XR100; either custom collars or drill out the XR frame to suit. I went with a custom 1 piece collar so as not to weaken the frame (which isn't all that solid to begin with).

As much as XR with full CR suspension conversions are more rare than CR with XR engine conversions, the CR frame with XR100 engine is IMO a much better bike overall. Requires less work, stronger frame, better geometry more options for aftermarket parts. However, if you want to turn heads in a knowledgeable crowd...

You will also have to alter the brake lever and weld the master cylinder bracket to the XR frame (not a big deal).

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Thanks for the input. I was thinking the same on the steering stem my other idea is to take the CR85 stem and machine it down and shorten to fit the XR frame. Like we all know the rear suspension will be the challenge. I can't start getting into it for a couple of weeks I have the Elsinore GP I'm racing next weekend so I'm focusing on that for now. Thanks again.

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