ORIGINAL: rcdude7
I just put new bearings in a saito 150 and I guess the front bearing seated slightly deeper than the orignal because I now have rod contact with the backplate. I took care of that clearance problem with a pnumatic die grinder w/sanding disk on the backplate. No more interferance problem!
That's an odd defect. You're positive the rear bearing was fully seated? I mean the parts are made to a certain size. If the bore for the front bearing was too deep, it should have been rejected before assembly. That problem just doesn't sound right. Either the bearings or the crank weren't seated correctly.
I had an NIB OS FS-26 that rubbed the backplate. It turned out the crank was an unusually tight fit in the bearings and wasn't fully seated.