That one is a 1949, I think it was the last year for the rubber band front suspension. After that they went to a Hydra-Glide type setup.
They also dropped the Bosch electrics around this time. My 57 was Delco, also 6V. All of the Hummers used the German Bing carburetors.
I remember my 1968 Sportster had a Bosch regulator, but a delco generator, and a Fairbanks-Morse magneto, no battery.
Sitting at a light at night we had to keep them revved to around a thousand RPM's to keep from getting hit in the ass by a cager.
The regulators would go bad after a couple dozen trips through the two bit car wash. After forking over $65- a couple times at the H-D shop I wised up and went to a V-W dealership and got the same thing for about eight dollars. A mag could be had off of a Wisconsin V-Twin for about thirty bucks, and the Tillotson carb rebuild kits could be bought at any snowmobile dealership for a few dollars.
As far as the Sportster tank...........well, now you know the rest of the story.
BTW, the first year of the Sportster was 1957, the year after the last K Model wich was the same thing only a 750cc flathead.
A photo of me and my 68 PaintShaker.
