I don't think it matters whether an engine has a wet sump oil system, a dry sump oil system or whether the oil is mixed with the fuel. Ring end gap is important for proper combustion and overall efficiency of an engine and may even be more citical in a two cycle in that ring blowby will contaminate the incoming fuel/air charge. In an ideal world there should be zero end gap in an engine that has reached proper operating temperature but that state is nearly impossible to achieve and may be undesireable in an overheated engine. Ring end gap is quite easy to measure. Place the ring in the bore and square it in the bore with the piston crown. To get real fussy and check for cylinder taper it should be measured in position at the top of the stroke and the bottom. Simply use a good quality set of feeler gages and use the old "go/no go" method of obtaining a very accurate end gap measurement.

Well, that's what I think.

Regards,
Bill