it is verry easy to check the timing of the ignition. The prophub has a diameter of 34mm. that give us a radius 17mm.
The circumference of the hub is 2x pi x r = 2 x 3.14 x 17 = 106.76mm
It is 360degrees in a circle. so 106.76 / 360 give us mm
pr. degree.
106.76 / 360 = 0.29655555. one degre is about 0.3mm.
so if you want 40deg. advanced timing. you will meassure 12mm between center of the magnet and center of the cencor when your piston is att top.
40deg. is what it is set att the factory, and I have that on my val. But the one i have in the storch i had to set the timing to 30deg. that is the other type of this engine with 3 piston rings ang higher compresion.