Stanley,

Depending on the condition of the barrel it may be brought back to life. There is a trick!–It requires a lathe and a glass cutter, a good one. Set the barrel up in the lathe and get it running true. Improvise a device to hold the glass cutter in the tool holder. Cut a ring above and below the air passage. This will raise the outside edge of the barrel to increase its diameter just enough to "fill the gap" and aid in crankcase compression. Don’t go crazy with the cutting depth,—just enough to raise the edge to achieve the needed tolerance. Then reset the cutter to run left to right in the tool holder and make a left to right "cut" along the barrel near the air passage opening on both sides. Those raised edges fill the gaps created when the barrel wobbled and they will sort of self adjust to their surrounding and you should once again have an efficient valve……or you could look for a better barrel.

I assume you have rebuilt the valve and installed new bearings?–Don’t do the trick w/out having new bearings.

George