Scooterotica

Just want to check my crank to make sure its running true,What is the tolerance for a highly tuned motor? Running the dial indicator gauge on the edges of the webs,ie where conrod comes out.

ideally less that .001" (inches).

take your measurement at several points, not just the center of the crank. Any alignment issues will be very apparent as you get closer to the end points. Multiple dial indicators help a lot here.

My machinist measures them on his lathe holding them between two centers (which need to be perfect). Measures them for twist, toe in and toe out.

The easiest way to check a crank for misalignment is mount it on two v blocks on the bearing diametres and then check the run out with a dial guage on the small end of the taper.(Or this can be done with the crank in situ.)Run out should be no more than a .001" has stated above.

I got 0.06 mm on the end of the flywheel taper.0.08mm and 0.09mm,total deflection on edges of webs,down the cylinder opening.Thoughts please.

The way I've seen it done was to mark the high spots and then adjust the webs with a copper hammer. Being the first one you're doing, there will be a big learning curve here. Might be best to take it to a shop and have them do it.

Was planning on that,just for peace of mind

Harry Barlow at Leicester could re-true youre crank