There’s a good chance that many of you have never heard of an Allstate motorcycle. They were produced by Puch in Austria and sold in Sears, Roebuck, and Co. catalogs under the Allstate brand name for nearly two decades.
While our mechanics had certainly heard of Allstate motorcycles, this was their first opportunity to personally work on one. This 1954 Allstate 175 (pictured above) was brought to us in September with the goals to get running, replace cables, replace the twist throttle grip, and address a shifter seal leak. Although cosmetically it arrived in excellent condition and didn’t at all allude to the fact that it was now a 65 year old motorcycle, the task seemed tall given the relative rarity of these machines, and thus the scarce availability of replacement parts.
Image source: Sears Allstate Riders
After testing for good compression and finding the engine to be free, we decided to first tackle the carburetors to get it running soundly. We cleaned the carburetor and ensured the jets and passageways were clear to allow proper fuel flow. To operate the carburetor, we then custom fabricated a throttle cable.
Next, we cleaned the points and successfully got it running.
Next, we cleaned the points and successfully got it running.
Although our work is nearing completion, we are still navigating the process of addressing an ongoing charging issue. It is common during the unlayering process of getting these vintage bikes running to discover new problems only after other problems are successfully solved. In this case, it required first getting the motorcycle running for the charging problem to present itself.
While researching Allstate motorcycles for a richer understanding and history of these machines, we stumbled upon a diagram (pictured below) depicting a “Split-Single Two Stroke”. As our mechanics had never even heard of such a concept, they were initially very skeptical that the particular machine we had held this same design. Their skepticism was disproved with a closer inspection through the spark plug hole with a borescope. To their delight and amazement, enclosed were two pistons within the same cylinder.
We later found that a twin piston single has been dubbed the ever-appropriate nickname of a “Twingle”, meaning “twin single”.
Image source: Sears Allstate Riders
This design is unique because there are two pistons operating within the same combustion chamber. On both the upward and downward movement, the pistons are in slightly staggered height positions. When they reach TDC (top dead center) they achieve matching heights simultaneously.
This uncommon bike with it’s peculiar engine design has shown us that even old dogs can learn new tricks. We’re sure this will be a talking point for years to come and hope to one day have an opportunity to split one of these engines apart to see a twin single firsthand.
Image Source: ClassicJapCycles.com
