Only engines with a purposely unbalanced flywheel have only one crank web, Q35, 42, Sachs 2.4, etc...The old Homelite Super Hustler II had a single counterbalance crank just like a Quadra..There was no flywheel, the engine had points and a battery..The steel hub was ground away almost to the crank on one side, same as a flywheel made purposely out of balance.....The Super Hustler II turned a 20-10 Master Airscrew about 6000 rpm, got way smoother at that rpm....
Dario Brisighella sold "overbalanced" flywheels for the old Quadras, made 'em smoother...
Seems like the cost was about $10...[8D]