I quit riding a motorcycle about ten years ago, because it was just too scary, but every now and then, I think about maybe getting back on a two-wheeler. This machine might just do it:
The plans call for individual engines coupled together with a double-sided drive belt in sets of three in alternating V configurations. In other words, a set with one engine above and two below alternated with a set of two above and one below. An additional drive belt will be arranged between the rows of engines. The original centrifugal clutches on the chainsaws will be used. And a two-speed transmission is suggested to transmit the power to the rear wheel. (Later a 5-speed Harley-Davidson transmission is substituted.) The bike will be called the Dolmette.
The engines are the PS-7900 professional chainsaw engines. In standard trim, each of these high-performance, air-cooled, 79-cc engines generates about 6.3 horsepower at 9,500 r.p.m. For use in the Dolmette, the engines were tuned and tweaked to deliver about 7.1 h.p. at 10,000 r.p.m. Maximum torque delivery is 4.1 foot-pounds at 7,750 r.p.m.
Ultimately, the design for the powerplant was increased to 24 engines. When all are combined, the result is a 24-cylinder unit with a displacement of 1.9 liters and output of 170 h.p. and 95.9 foot-pounds of torque at the centrifugal clutches, both large for a motorcycle.
Link to article in Chicago Tribune (free reg req'd)