If you ever loved a two-stroke, even though you may not know it, you partly have Alfred Scott to thank. He designed his first vertical twin two-stroke engine in 1904. It was a 450cc engine mounted in a V-shaped frame that tucked the fuel tank down between the rider’s legs, for better ease of riding. Scott’s two-stroke design was the first ever to complete the Isle of Man TT course in 1910.
From 1911 to 1914, Scott handily set new IOM course lap records. Soon, Scott was so competitive at IOM events that, for his sins, he was penalized by having engine displacement multiplied by 1.32 as a handicap. Pretty soon, he was competing against four-stroke bikes of much higher displacement.
Now, about this specific bike. Scott’s Squirrels were race homologation models, which offered 486cc of displacement from their water-cooled two-stroke vertical twin engines. This particular one was restored for Steve McQueen by Kenny Howard—who you may know better as Von Dutch. McQueen later regifted this bike back to Von Dutch, who later sold it.