If your planning to upgrade the rear suspension on your TZR250 you have two options. You can order a custom rear shock with all of the latest goodies, or see if you find a shock from another late model bike that fits.
I went with the second option.

If you have an early TZR, the 1KT model, then the 1999 to 2002 Yamaha YZF600 R6 shock bolts right in. The original shock is 291mm eye to eye and the R6 shock is 306, and the reservoir on the R6 shock is turned sideways so it clears the chain and swingarm. The longer R6 shock will lift the back end by about 25mm (1 inch), which will add ground clearance and steepen the steering head angle for quicker steering. The spring is a bit soft so your going to have to crank the preload up to the max. Set the compression and rebound damping settings at the stock positions minus two clicks on each.

The 2003 to 2005 Yamaha YZF600 R6 shock you can't use. The reservoir is vertical so it won't fit in. That's too bad cause its really trick looking. They also have eye joints on both ends but I haven't bought one so I'm not sure of the length.

If you have a 2XT or 2MA TZR250 then your going to have to do a bit of work to get a 2006 Yamaha YZF600 R6 shock to fit. But its worth it, because this factory shock has all the options including HIGH and LOW compression damping adjustments along with the rebound damping. The late model TZR shock is 270mm eye to clevis and the R6 shock is 291 eye to clevis. Thats more than 21mm (13/16 of an inch) longer, which jacks up the rear end by 56mm (2-1/4") if new trailingarms aren't installed. Two spacers for the top mount also have to be made and a bit machined off of the shock too.

The lower clevis mount has to be machined so it will fit onto the monocross link. As can be seen in the following picture, I've made a quick set up in a 3-jaw chuck, mounted to a rotary table, in my vertical mill. The end has to be radiused to clear the mount for the trailing arms.

I've made a few drawings so you have exact dimensions for what has to be made and machined.

The two washer like spacers are for the upper mount, one on either side. The stock trailing arms are 112.5mm center to center and making longer ones of 128mm moves the back end up by about 25mm (1 inch) from stock.
Exactly where I want it.

CONTACT ME AT TIMOTHY@NAUGHTYBOYMOTORRACING.COM