Twingle

In internal combustion engines, a split-single design is a type of two-stroke where two cylinders share a single combustion chamber. The first production split-single engine was built in 1918 and the design was used on several motorcycles and cars until the mid-1950s, although Puch continued producing split-single engines for motorcycles until 1970. During this time, the design was occasionally used for engines with four or more cylinders.