I put this in the wrong thread more as a comment, Removed head from 1951 A7, running fine, no smoke and starts first kick and idles easily at low revs. but prior to me purchasing bike it had been in storage for abt 20 yrs. It has been rebored out to max. Exhaust valves were rough but have cleaned up well, and on one side I found a crack running through the spark plug hole through the exhaust seat. just wondering if if this is a common problem, it was easy to miss had to use a magnifying glass
Steve
