For the 1950 racing season, Harley engineers mounted their trusty Wico single-fire magneto up front, horizontally(again) and made up this really neato -50R gear cover. It has an access door to "easily" change your ignition timing if you feel so inclined. Here's the kicker. You don't just move loosen the magneto and move-it to adjust it. You unbolt this cone-shaped gear, that locates on a pin and is secured by the center nut. It has multiple positions to achieve the degrees in timing you need. Some smart cookie figured out which hole you need to use to get the precise degree or advance or retard. Moving one hole doesn't mean "a little bit more" . . . the ratio of holes to gear teeth is not consistent or uniform. This is a real head scratcher too. I won't even go into how to time this thing, 11/32" and large lobes and #1 is rear cylinder . . . or I'll be confused(again), and you'll be newly confused. The moral of the story is don't let it go out the door unless you know it's right. Right?