Motorcycle Dyno And Motorcycle Dyno Videos

One purpose of dynamometer testing is to measure an engine's horsepower and torque curves. A dynamometer is an invaluable tool to anyone working with motors. A dynamometer, or dyno, measures power output from a motorcycle’s engine by either connecting to the countershaft (front) sprocket or a rolling drum that the rear wheel spins. Cycle World’s dyno is a roller drum, sometimes called a chassis dyno.

As a part of our motorcycle review and motorcycle comparison process, we run all of the motorcycles that come to us on the dyno and add it to our motorcycle dyno video library. Whether it be a 125cc Honda Cub or a supercharged Kawasaki Ninja H2, any motorcycle that comes into our garage is guaranteed to see the dyno.

Motorcycle manufacturers publish specs for their bikes, breaking down trail, tire size, engine components, compression ratio, stroke, and most importantly engine power figures. Engine power is rated in horsepower (hp), or in kilowatts (kW) for those using the metric system. The measurement for torque, or the rotational force generated by the engine, is pound-feet (lb.-ft.), but you will also see Newton-meters (Nm) as another unit for torque measurement.

Most modern motorcycle dynamometers operate one of two ways, depending on where they measure power output from. An engine dynamometer measures power output at the crankshaft of the motorcycle and this normally occurs with the engine not mounted in the bike. This is where most manufacturers obtain their power numbers from.

The more common type of dyno that you see, and the one located in our Cycle World office, is called a roller drum, or chassis, dyno. This operates by placing the motorcycle’s rear wheel in contact with the roller drum and having the torque produced by the wheel spinning the drum.

Brake horsepower (bhp) and wheel horsepower—whp, rwhp, fwhp, or awhp—are a creation of the testing methods of engine torque. Engine power measured from the countershaft, or front sprocket, is called brake horsepower. Engine power measured from the wheel is aptly called wheel horsepower.

Wheel horsepower is measured on a chassis dyno, and is a more accurate representation of real-world power. Wheel horsepower takes into account power losses from the drivetrain, fluids, clutch, and rotational mass such as the rear wheel because the motorcycle’s power is measured with all of these items interacting with the engine and dyno. 

Brake horsepower will most likely be the power numbers that you see listed on a manufacturer’s website. No, they are not lying to you, that engine does produce 200 hp, but doesn’t drive 200 hp to the rear wheel. A rule of thumb is to take 10 to 15 percent off of that power number you see on a manufacturer’s website. That should give you a good approximation for wheel horsepower of that bike.