Originally Posted by FBinNY

There is one way to do this job right. If there's enough meat on the stem you can ream the 25.4 bore out to 26mm. You'll need an adjustable blade reamer (or fixed 26mm reamer) of the type shops use for seat tubes, and a bit of skill to do a workmanlike job. Any decent bike shop mechanic should be able to do it, or you can mail me the stem and I'll do it for $10.00 including return postage.