The plugs are not fragile in use, but they are fragile to handle. That is what I meant. The 1/4-32 plugs are readily available, as Bill mentioned.

Is the mag placed into the cam? I wonder how to properly set the timing on a 4 stroke otherwise. Don't want it firing on the wrong stroke!

I know CH has converted many 2-stroke and 4-stroke glow engines so they must have a method.