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.
You can see from this cutaway that the bores are offset so the pistons are slightly out of phase. The rear barrel contains the transfer ports and the front, the exhaust port. I'm not entirely sure what the perceived advantages in this layout is, but Puch (and others) built split singles for a number of years. This diagram (not of a Puch) gives an idea of how the system works.
James Dean on a Puch - cool or what?
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!
Oops!
Talking of Lewis and Clark, the first time I'd heard about them was the Long Ryders singing on The Old Grey Whistle Test.
When I bought my first bike, my father suggested we go to Sears and check out the motorcycles there. They had the 250 Twingle and Benelli made 106 'Supersports'. We sat on them and after I made remarks about how quaint they were, and started listing all the modern advances available like overhead cams and electric starters and the like, he said something like 'I see you've done your research, o.k. off to the Honda shop'. I liked the looks of them, but had ridden enough bikes by then to have a fair idea of what I really wanted, a 750 Honda or a Commando. Of course I had to settle for a 175 and wait a few years for the 750's.
ReplyDeleteI found a mention at a newsletter of the Twingle expedition.
ReplyDeletewww.richmondriders.com/newsletters/sep07.pdf
There were links to a lot of other people following the expedition route, but not on Sears Allstates. My sister and her husband tried to stop at as many waypoints as they could from the highways on a mini-motor home trip they did a couple years ago.
PBS ran a Ken Burns documentary on the Lewis and Clark Expedition.
www.pbs.org/lewisandclark/
Might be able to watch episodes of it there.