Pro Stock Motorcycle Pro Stock Motorcycle Pro Stock Motorcycle, formerly known as Pro Stock Bike, is a motorcycle drag racing class that is the two-wheeled equivalent of Pro Stock. It has been a feature of NHRA drag racing since the 1980s when it was added to the professional class structure and has since spread around the globe. The first points championship season was the 1987 NHRA season. The class has for years been dominated by inline-4 cylinder Suzuki based bikes but in recent years Harley-Davidson based V-twin machines have become more competitive due to favorable rule changes (160 c.i. Harleys vs. 107 c.i
BSA unit twins new cycle parts, including the "oil-bearing frame". Apart from cosmetic items, the cycle parts were shared with the Triumph twins. (Triumph was a subsidiary of BSA). To produce a 750cc machine for AMA Class C racing, BSA lengthened the stroke of Lightening's crankshaft by 11mm to give a displacement of 751cc. 202 machines were produced to meet the minimum production requirements. All were exported to the US, most to the East Coast distributor in Baltimore. By 1972 BSA were in serious financial trouble and the Firebird Scrambler was discontinued in an attempt to reduce costs. With rival British motorcycle manufacturer,