Where would they have fitted a generator?
The KL model was originally planned for release in the early 50's. Instead, the poor performing K model was rushed into production to fill it's gap. The high cam KL was continuously plagued by overheating problems, so the later (1954), experimental XL overhead design superseded it. At one point both the KL and XL were being tested side by side. Harley originally didn't want an overhead design based on the old flathead four cam bottom, but it worked and it's performance pretty much surprised everyone. What shouldn't be a surprise is that the XL's top end was designed by the same guy (Charley Featherly), who had done detailed work on the Knucklehead and later the Shovelhead. Since early Panheads had trouble with their aluminum heads, he stuck with iron like on Knuckles. Charley also thought that the valve covers on Pans held too much heat.
