A 1934 BMW R7 a nice looking Bike 
This is
not the bike I'm making right now, although it might be my next one. Seriously beautiful bike:

Maybe too many swoops for me to make out of plasticard though. (Those fenders would be hell.) Might be more of a putty job.
You're very warm with this guess though, in that the bike I'm making also has an enclosed engine.