1956 Moto Guzzi Airone Sport

Left side of engine showing external flywheel right next to the rider's footpeg.
Wouldn't the American safety bureaucrats freak if they saw this?

Making the flywheel external meant the didn't have to build a case for it, which saved some weight. With a smooth finish on the flywheel and proper footwear on the rider (leather boots), there should have been was little chance for trouble.
More pictures of the bike here. They started building it in 1939, but production was soon interrupted by the war. They resumed building it after the war and continued up till 1957.