McFarland made me a new longer precision center so I can check run-out on short parts. I've got a 60s Sporty motor of Polgreen's that we're rebuilding from parts. I picked out the nicest lookin' set of flywheels and started checking each 1/2 for run-out like I always do. The left (sprocket-side wheel) had like +.025-.030 run-out on the face. The shaft itself was dead nuts perfect. I popped it apart, and it didn't really have the right key . . . but, the tapers looked ok. We tried it with the new key, but still has +.025. I mean zero run-out would be nice, but Lakeshore H-D says +.007 is acceptable way out on the face. ABOVE PHOTOs: We even checked the shaft flange and the nut for run-out. If you think about it . . . if the nut was off, it could possibly "kink" or pull the shaft possibly. Diagnosis: Shaft ok - Taper in flywheel is damaged or just machined wrong. We checked out his other set of flywheels, and they are much better, +.005 before we trued each 1/2 - we'll use those. Maybe all that run-out wouldn't make much of a difference, but it would probably wear out your Timken prematurely, or vibrate at certain speeds, or just be a mutt of a motor with not much power. Just keepin' old Harley's alive . . . everyday.