RE: 4 cycle lubrication
I had two of these 61's, an ASP and a Magnum. They were the same except for the name.
The Magnum had a leaky exhaust valve. I tried all sorts of lapping things to get it to seat completely but was never successful.
However, in running the engines, the Magnum ran just as good as the ASP.
I traded the engines to a friend. He uses the Magnum more than the ASP. He's had them for 5 years and never done anything to the Magnum except use it.
I suppose it still leaks?