I found this old post when searching for a way to make sure that the magneto is in line. Well, all is relative, but I think that one should try to make the best of it.
Yes, the alignment of the magneto sprockets also caused me so head scratching! I was thinking about some form of laser pointer, too. But how should one attach such a device? The chain alignment tools that you can buy is placed on a flat surface of the (rear) sprocket. Then you can see the beam along the chain to the other sprocket.
The problem is that the Scott magneto sprocket has hardly any flat surface. This is what I came up with today, simply some straight bar attached to the magneto sprocket. Then you can “rest” this bar against the crankshaft sproket by adjusting the magneto. I think that the included pictures explains the whole thing. The camfer on the crankshaft end is to avid contact with the crankcase. The only snag is that you can’t use this device with the chain in place. On the other hand,once done, you can shribe two lines on the magneto platform, so you can return the magneto in the same place, if you’re forced to remove it.
As I’ve been working with mechanical constructions for forty years, I’ve come to the conclusion that the simplest (=mostly the best!) constructions is the hardest to think up! It’s all too easy to go overboard and adding complications!