I haven’t updated this in several months, mainly because I haven’t progressed enough to have anything new to show. I decided that I definitely want to go with a Bultaco engine, for several reasons: 1) I like Bultacos. I’ve owned three of them, and they’re great motors. 2) I know Bultacos (See Point #1). 3) Any other motor would require additional frame modification, and thus time and expense. 4) I would like the finished product to be “a Bultaco” rather than a mongrel combination of engine and frame. That might also help me get a street title for this bike.
So I’ve slowed down while looking around for just the right Bul motor. Even though any Bul 5-speed engine will fit my frame, they’re not all identical. I am being a bit picky about the particular model I go with. In keeping with the budget aspect, the asking prices for complete Bultaco motors vary widely. I would rather bide my time and find something that’s not at the top of the price range.
In the meantime, I bought a set dummy set of Bultaco engine cases to use while making up the swingarm pivot. I also bought a stock rear engine mounting bracket. Not sure which way I am going to go at this point, but I’ve definitely reined in (or perhaps restricted) my options a lot by settling on an engine design.