The Enya plugs are occasionaly seen, They are somewhat expensive. You see them in four strokes about as often as 2 strokes.

The plug of choice for the four strokes is the OS "F".

The OS #8 is sometimes seen in 2 stroke engines but the OS A3 is much more common due to the cost.

There are complete lists of popular plugs and how the heat ranges run on here somewhere?

One company's hot plug may be colder than another's cold plug. There are no set standards. About the only thing you can rely on is the heat ranges within a certain brand.

Enjoy,

Jim