Thanx for your reply. Piston was scored and seized, because of user error. My wife was participating in the True Grits 50cc Fun Run and forgot that running full-throttle on a 45-year old two-stroke could cause problems.
Their are now 2-stroke oils on market now, specifically for oil and water...
Just replaced burned piston on my 1965 Harley M-65 and don't want to do it again. Owners manual specifies 25:1 ratio with SAE 30 Harley-Davidson two-stroke oil, which may be real hard to find. What have others found for antique air-cooled 2 stroke motorcycles that are actually ridden?