I picked up a rear shock from a Raptor 125 ATV for $30 shipped. It’ll barely fit in the space available, but the Raptor 125 weighs about 300 lbs, (which is right around where I expect this bike to end up) and from what I read online, can handle a 200+ lb. adult rider quite well. It has about 2″ of travel, which should also work nicely. Of course, all this might be totally wrong once I get it together, but anything short of a $500 custom-calibrated Ohlins monoshock is a total crapshoot. At the very least, this one’s basically brand new and not total crap to start with. Given my bargain-basement strategy for this bike, it’s probably the best I can expect to find.
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“…then Goldilocks said, ‘this one’s juuust right!'”
The Raptor 125 shock flanked by the XR100 and ZX-7 shocks purchased previously. The Raptor shock is actually longer eye-to-eye than the ZX-7’s, but the diameter is smaller and it doesn’t have that huge reservoir sticking out from it…not to mention spring and damping rates more in the ballpark for a lightweight roadster. (The spring retainer has already been removed from the Raptor shock.)
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My no-buck spring compressor. Since the shock eye was actually bolted through the jack arm and I was using two separate Ancra tie-down straps, I figured it was a reasonably safe way to do it.
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The shock position mocked up w/ front patterns of HDPE and rear arms made from aluminum channel. Of course, neither of the two shock linkages from production bikes that I’ve purchased to use there will work — one’s too short and one is too long. I have to work out just the right length; there’s a very narrow window between the shock hitting the swingarm and hitting the frame at some point within the range of suspension travel. I haven’t had a chance to play with the dogbone links from the rear eye to the swingarm, but I’m considering some sort of turnbuckle linkages so I can adjust ride height after it’s all together.
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The dogbones (or turnbuckles) will have to attach outboard of the swingarm mounts, since the Raptor spring is just narrow enough to fit between the two sides of the swingarm.