Ok guys, add one more to the list of riders attempting the USD fork swap to an XR frame. Quite a bit of research here on TT and ebay hunting brought me a pretty good deal on a set of forks, triples, and stem from a 00' CR 250. There are a few different options for adapting CR style forks to an XR. Bushings for upper and lower CR triples can be made to allow use of the stock XR stem. Specialty bearings can also be purchased to allow use of the stock CR stem in the XR neck. And finally what seems to be the most common; modification of the stock CR stem to allow use of XR sized bearings. I obviously chose to pursue the third option for a few reasons, the most prominent of which is serviceability. I wanted to keep as many wear items at possible as stock parts. This has two advantages; availability and price of replacement parts. $45 dollar a pop "specialty" thin section tapered bearings don't sound too appealing especially when being used on a 12 year old dirtbike. So now we can get to the meat of the issue; modification of the CR stem. I should begin by saying that i am NOT a draftsman. I've taken a few classes on engineering measurements but am far from an expert and probably only mildly proficient reverse modeling components. With that said, the first order of business was comparing an XR stem and bearings to a CR stem and bearings. Shown below. A little closer look at the XR setup. And the CR setup. Now to get out the calipers and model up the stock CR piece. I used a cheaper set of calipers and suspect their tolerance is +/- .01mm. Good enough for gov'ment work though! All dimensions in millimeters. Now to modify the CR stem to work with the XR bearings while remaining compatible with CR triple trees. There are a few things to say about why i did some things the way i did but most of the thoughts are included in the notes section of the drawing. With a resized stem we run into the problem of mounting the top triple clamp. The hole is too large for the stem. An insert bushing must be made to resize the hole in the clamp. Finally what the stem and bushing look like together. Last one. The difference in how the top triple clamp is located on the stem. The CR is equipped with a chamfer that provides a stop for the tree while the XR's triple appears to be limited only by the threads for the castle nut. So... would like to hear your opinions on the execution of the stem modification and bushing. I think having these drawings will make it simpler to have the modifications performed as opposed to asking the machinist to completely reverse engineer the part him/herself. And a final query: Anyone know the thread callout for the two threaded portion of a stock XR steering stem? My drawings show the outside diameter of the threaded portions and i have a cheap plastic pitch gauge that tells me a pitch of 1.0 but i am looking for something more concrete than what i have. Thanks for your thoughts and opinions.