Hi Lou

My supertigers are ringed. If they were abc or aac or any other none ringed type they would diesel much better,
The contra piston in the DD head is pretty small .680 compared to the bore 1.1" so two turns is not excessive.
From cold it takes a lot of spinning to warm the cyl/ compression chamber so it will fire. Even then it is a put put mis kind of run until things warm up.
Most authorities recommend a lesser percentage lube oil in ball bearing engines.
I don't want to damage the engines so I haven't experimented too much with less oil. Most of my mixes are 30%ether and 30% Klotz benol oil, 3% amsoil cetane booster with the remainder kero