During 1928, Joe Petrali (who switched back and forth between Harley-Davidson and Excelsior) was joined by Gene Rhyne as a factory rider for the Schwinn company. The two teammates won both flat track and hillclimb events for the Chicago manufacturer who, for the most part, had ignored competition since Bob Perry's death in 1920. His interest in racing rekindled, Schwinn instructed his chief engineer, Arthur "Connie" Constantine (designer of the H-D "Peashooter" and the Super X) to build an overhead 45 that could successfully compete with Indian for the 1929 National Hillclimb Championship.
Using a standard Super X as the basis for his motor, Constantine changed the ratio between the bore and the stroke and designed hemispherical combustion chambers with oversize valves (the old Excelsior strategy). The overhead-valves were compressed by double chrome vanadium wire springs, each cylinder exhausting through twin ports. The new motor (with a compression ratio of 10:1) was designed to run on alcohol-benzol fuel, and when dyno-tested was said to develop one horsepower per cubic inch!
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