by thefrenchowl » Wed Sep 16, 2015 4:55 pm
Hi Eric,
Top tree with 4 tabs for switches can be K or XL. Both available as K (52/E54) or KH/X (L54/58) geometries...
As a quick check, hole for steering shaft is contained within the angle formed by the back edges lines of the top tree on the K and KR/XLR trees. I call these K geometry. Also used on early KH.
These 2 top tree back edges lines converge towards the middle of the steering hole on the KH/X top tree cause they pulled back the hole to bring the fork tubes parallel to the steering axis and changed both top and bottom castings to suit. I call these KH/X geometry
Except on mid year KH when they actually moded/cut/welded the existing K top and bottom trees to KH/X geometry (the new castings were either not available yet or K type moded as penny pinching measure)
You can clearly see on the above factory XLRTT shots that the tubes are not parallel to the steering axis, that's K geometry.
But the frame on this XLRTT prototype is a pre 57 KR frame. When the proper -58R race frame came for the privateers XLRTT and KRs after 1958, they both had the Sportster top stamped steel motor mount.
The rare (I only saw one once...) -57R frame for the KR only is a goose neck race frame with the K top mount casting.
Back to the top tree that started this topic... I can't comment, having no idea what is fitted on the real bike, race or street items...
Guys wanting advise on such rarefied stuff should put photos on... ; - )
Jerry was kind enough to post photos of a frame, and I can date it "post 58" by looking at the thick webbed seat casting and top stamped motor mount, deffo Sportster items, mixed with K geometry front steering casting... You won't see that combination in any K, KH or X street frames!
Paul, yours a street frame... When you repair the oil tank mount bracket, don't braze it, it is actually silver brazed (lower melting temps, better capilarity and stronger than brazing...) like the whole rest of the tube/cast junctions...
Patrick