I recently built a crank press jig. It is essentially the same design as others on the market but machined specifically for Honda RS125 NX4 cranks. A 1" thick steel top plate slides on four 1" hardened shafts which are fixed to a thicker bottom plate. Both plates are precision machined on all sides. I bored all the holes in one operation to maximize accuracy. The center holes were bored just large enough for the crank journals to slip fit through. I made four stand-offs which slip over the shafts to stop the top plate from over-pressing the crank. So far it seems to work well. I've rebuilt two cranks with the jig. Both came out within .001" straight out of the jig. That would be good enough to run as-is. But I was curious if I could get it even closer. A few adjustments with the brass hammer and I managed to get one crank down to .0001-.0002". The jig is very simple, yet especially effective with the Honda style cranks that have the sheetmetal covers, as it is difficult to accurately align the two crank halves otherwise. I'm happy with it. I might make more!
