Got it all sorted out today. A small tweak to each curve got it clear of the crank. My mistake was measuring my curve from the tip of the expansion chamber, then welding the new piece on at the end of the chamber. The tip extends 3/4" past there. The original plan was to put a bracket on the end of the chamber and one on the pipe to bolt them together, but I was having too much fun throwing arcs so they got welded.
Anyway, I had to make some hangers. I went with a 3 piece design, a loop over the chainstay, a straight piece, and a loop around the pipe.
Here's the finished result:
New exhaust installed.jpg
The next thing it's getting will be a reed valve (got to look them up shortly).
This is what it sounded like with just the expansion chamber
This is what it sounds like with the completed exhaust pipe
installed. (I discovered after recording that the exhaust studs needed another half turn or so since it had warmed up so it was making a small drip under the port).
Just a little difference. I didn't adjust the idle screw between shots, honest.
Got to take it out for a spin, it's supposed to rain tomorrow, it should be better Wednesday or Thursday.