This is unusual in that it is a two stroke 'split single', also know as a 'Twingle', as it has two bores but a common combustion chamber. The conrods are connected to a common crankpin so the pistons rise and fall together.
However, while I was looking up details of the Puch, I came across a really interesting article on a group of riders attempting an 8,000 mile (13,000 km) trip across the US on Puch/Allstate 250s, retracing the journey made in 1804-06 by a party lead by explorers Lewis and Clark. I've searched the Internet, but can't find any more details of this trip (anyone help?)
It looks like things didn't always go to plan!
Talking of Lewis and Clark, the first time I'd heard about them was the Long Ryders singing on The Old Grey Whistle Test.