I changed the dynamo pulley on my bike this morning.
I followed the fitting advice and allowed a twist of 45° each way on the bottom run.
https://youtu.be/WpAAWnoPp2IThis is almost certainly the last bit of tinkering I will do on that motorcycle.
PS., while I'm here, do you have any idea what that little screw is doing in the timing case; it was there when I bought the bike. I can only surmise it's something to do with the A&R unit. The hole for the screw is only about 2mm.
PPS. In the next picture you can see the 'High Capacity' steel/iron bodied oil pump I fitted when I was restoring the bike.