Seen at the Fast Eddie's Motorfest in Stouffville. Sept 7 2019.
The owner restored the bike and said he rebuilt the vertically split two cylinder engine, not a straightforward design. The clutch lives on the left end of the crankshaft and the gear change mechanism is a disc located on the bottom of the engine.
I gave up on a Big Bear project in the pre-internet years (the shifter mechanism came disassembled in a box) when you could not find parts or information for any old bike. I do like the scrambler pipes.