This is an old red 3.7 ci. (early 80's AYP?) saw that used to run like a horse. Now it has become a bit of a project saw, mainly to teach my kids how 2-cycle engines work. Problem I've recently run into is, it stalls out after a few minutes of fire...seemingly after it warms up. It has no trouble starting (when cold), but once it gets going, its quite a bear. The suggested fuel is 1:16, but I've been using a little lighter (1:24). Could it be as simple as using the thicker fuel mix? Is it vapor lock? Carb?

The saw has plenty of compression and spark....which leads me to the fuel issues.

Any help is much appreciated.