Hi,
I have measures many engines and found that most chain saws have about the same timing. Trimmer engines vary quite a bit. Here are some numbers. If you want exact numbers for a specific engine, let me know. I will see what I have.

Chain saw:

Intake 140 degrees duration
Exhust 150 degrees duration
Transfer 118 degrees duration


Trimmer:

Intake 110 to 132 degrees duration
Exhust 120 to 150 degrees duration
Transfer 100 to 118 degrees duration

Dave