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Installation
They come with installation instructions which basically say remove the caps & springs, remove old fork oil, put in some new fork oil, extend/compress forks a few times to get out air bubbles, drop in the valves, cover with oil, get air out, set oil level, install springs & cut down spacers, install caps, and off you go.
Not being sure whether they would fit the 250 (as these are sold for the 300), I decided to check the fit before installing them. The valves fit within the fork tube just fine. Next I pulled out a damper tube to see if would fit. To remove a tube easily, put bike on rear stand and triple tree stand, pull off wheel, unscrew bolt at bottom hole of fork, remove fork spring, then use an extendable magnet to pull up the damper.
It appears the o-ring is intended to slide down into the ID of the damper tube as this is required to have the valve sit 25 mm above the top of the damper (and the instructions mention the 25mm in reference to fork spring & spacers). With my bike, the valve did not fit into the tube; the o-ring just wouldnt go into the damper tube. Measuring the OD of the valve (next to the oring) and the ID of the damper tube, there is only .002" difference between the two. For the oring to fit, it would need to completely collapse within its groove and it was just too thick and stiff to do so.
However, it would fit just fine without the oring. The first pic shows the oring installed on the valve, the next shows the valve , without oring, in place on the damper. The last pic shows about how far down the valve goes into the damper, and where the rebound hole is licated on the damper. Thus the valve does not affect the flow of oil going thru the damper rebound hole.
I put on my engineering hat and concluded that the lack of an oring would not impact damping performance. Im guessing its there for noise purposes and also saw that Mupo valves for some other bikes do not have orings either.
Convinced they were going to fit, I reinstalled the damper tube (use magnet to guide it in, install screw at bottom of fork, then pull magnet away). Then I followed the instructions up to the point where you drop the valve into the fork leg. The third pic shows a greenish looking strip in my fingers. This is the seal which goes into the groove between the upper and lower shim stacks and forces the fork oil to go thru the shim stacks instead of leaking past the valve. On my first few attempts to get the valve to go into the fork tubes, the seal was just a hair too long for the valve to fit. I ended up sanding the end of the seal a little at a time until the valve finally did fit. Be careful here, a sloppy job will let fork oil leak past the shimstacks. Once it fit, however, my magnet was not strong enough to pull it out so Ill probably need to push the valves with a rod thru the bottom hole of the fork leg if I ever need to remove them.
From this point, it was just a matter of following the directions to add oil and get the air out. The only trick really is that you need to push on something on top of the valves (i used forksprings & spacers) to extend the forks or else the valves will slide upwards from where they sit on the damper tubes. Once the oil level is set (i used the turkey baster and tubing method), cut your fork spring spacers 25mm (or the supplied spacers if they"re the right length for you), and reinstall the springs, washers, spacers, and fork caps, and thats basically it you are done.
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