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
Motorcycle engine systems, was a significant factor in forcing the redesign. Traditionally, engines and gearboxes had separate lubrication systems with different grades of oil; but modern practice is to use the same oil for both. The majority of motorcycle engines are configured as singles, parallel twins, triples, fours and sixes; and all these may be inline or transverse. Vee engines include V-twins and V-fours, and horizontally opposed engines include flat-twins, flat-fours and flat-sixes. Wankel engines are either single-rotor or twin-rotor. Bigger bikes tend to have more cylinders for smoothness and increased power. Modern singles range in capacity from 50 cc to 660