................................. I ran it a little and the timing mark on the plug wasn’t quite right so I removed the little plate so I could retard it a tad more. That put the heat mark right on the bend of the plug strap.
If this method works for you and it makes the most power without causing detonation I would continue using it as a tuning tool.
I have been modifying and tuning two stroke engines for a little over 50 years and have not found this method to be an indicator that an optimum timing setting has been reached and is a safe timing setting. I try to use a method when tuning an engine that will indicate whether there was a power increase or decrease when changing the timing or jetting watching the top of the piston, combustion chamber, and spark for signs of the onset of very mild detonation. The methods I use to determine a change in power are: the dyno, the drag striip where E. T. and MPH is recorded and roll on acceleration testing using two vehicles of similar performance, on a surface of maximum traction and compare how the acceleration changes as tuning changes are made.
I want to play the devils advocate for a minute..
My testing has shown the heat mark that you mentioned on the ground strap will move to different parts of the ground strap with different styles of spark plugs of the same heat range with the same timing setting and making exactly the same power. The total length of the ground strap, the cross sectional area of the ground strap, the amount of mass in the threaded shell where the ground strap attaches, the alloy that the ground strap is made of and the combustion temperature are the main parameters that affect the temperature of the ground strap. The heat mark on the ground strap will also move with a change in coolant temperature and alloy the cylinder head is made of.
