Production of singles was spotty after 1918, with a “half 74” produced half-heartedly from 1921-23. Smaller riders turned to other brands for suitable mounts, like the Indian Prince introduced in 1925. Harley-Davidson’s attitude to one-lungers changed after the AMA introduced a 21 CI racing series for 1925 (Class A racing), with Indian and Excelsior expected to provide the bulk of entries, as both factories built singles at that displacement.
Harley-Davidson, as usual, rose to the challenge, luring customers with a pair of new singles in 1926, the “A” and “B” 21 CI (350cc) models. There were both sidevalve engine models (the A with a magneto, or B with battery/coil), or one could choose a better-breathing OHV engine (the AA with magneto, or BA with coil ignition) with a whopping 50-percent more horsepower (to a total of 12 HP).
The sidevalver was cheaper and lighter, and it sold better than its OHV brother, regardless that the OHV would soon make a significant mark in the worldwide dirt-track racing craze. Both the OHV and sidevalve models had detachable cylinder heads (a first for Harley-Davidson), and the OHV had especially sprightly performance with its good power-to weight ratio. The BA shared a motor with the soon-to-be-legendary “Peashooter” dirt-track racer (the Model S), which had a shorter, lighter frame, which was identical to the Rudge speedway chassis. Many racers tuned the Model B overhead-valve engine for work on the track and modified their frames for short-track dirt racing.
This 1927 Model BA single appears to be just that; a home-tuned racer with a short-track frame, racing Schebler AMX12 carb, a magneto ignition and twin exhaust ports. It was restored in 1995 in factory-racing Olive-green livery, and is a thing of beauty—a terrific example of a Harley-Davidson single-cylinder racer.
Report by mecum.com