My bike came to me with a wobbly mag, which allowed oil to blow all round and into the mag itself. I idiotically overtightened the mag strap and broke it. When I finally got round to fixing it properly I used gasket paper under the mag and cut an extra piece for under the outboard end to get the mag shaft to line up properly with the engine seal. I can take no credit for this, I was advised to do it. Anyway it worked.
The magneto was wobbling on it's centre by the way and the seal housing was worn unevenly but fillable with a tiny bit of non hardening sealant. I think the case had been welded
The problem with completely machining away the recess for the seal to do the REME mod is accurately locating the correct centre of the newly machined hole into which the brass/aluminium seal holder will fit...
I made a jig for doing this job using a NOS set of crank cases to determine the correct location of the centre...
Another way which might determine the centre accurately enough would be to clamp the mag in place and then fit the mag gear...After adjustments to produce the correct gear mesh and with the mag straps fully tightened the gear could then be removed and the outside diameter of the magneto shaft clocked true...
This would require half the crank case to be mounted on parallel blocks with the mag attached and to be clamped to a milling machine table I would have thought...Obviously once the shaft is clocked the crank cases can't be moved in relation to the milling machine spindle..Ian
To find the center, I plan to fit the mag, mesh the gear, strap down and then remove the gear. I will machine a dummy sleeve to fit snug on the mag shaft and with the correct OD for the mod cutout. I will mark out around the OD of the dummy sleeve.
