Hello all, I have been looking over my Sportster frame and also a spare K model frame that I have trying to figure out just what all these codes and casting numbers signify. Now the casting numbers seem to be consistent on both my frames the what I believe to be a Sportster frame and the K model frame. There are slight differences though. For example the casting number on the underside of the sportster frame in the rear section by the seat is on the right side if looked at from the rear, the K model frame has those casting numbers on the underside but on the left side. On the right side there is also a flat part and a difference in the casting on the K model which looks like a place something was mounted but I am not sure what.
I also noticed on the REAR Gas tank mount just below the forward seat mount there is a letter and number stamped. On the K model frame it says K6 on the Sportster frame (I think its a Sportster frame) it says K3, What do these numbers/letters mean?
There is an old frame on ebay right now and the seller claims that its a 1957 Sportster frame because the letters/numbers stamped on his are 6I which would be 6 for 1956 and I because it is the 9th letter in the alphabet or the 9th month that year September 1956. This makes logical sense but is that what these numbers letters really mean? If so what do my K6 and K3 mean? I was pretty certain that my one frame was the Sportster frame but according to this method I guess the K3 would be November 1953....but the castings are different and the K3 frame looks exactly like my father's Sportster and the K model frame K6 I know thats a K model because the castings are different.
If any can shed some light on this subject please leave a message or e-mail me at Powerlifter626@yahoo.com