Motorcycle, Curtiss V-8

Motorcyle with Curtiss V-8 aircooled engine, 30-40 horsepower. Black overall with white tires.

Before achieving fame in aeronautics, Glenn Curtiss started his career with motorcycles. The early aviation community began to seek out Curtiss because of his growing reputation for designing powerful, lightweight motorcycle engines. In 1906 he designed his first V-8 engine in response to several requests from early aeronautical experimenters.

As a manufacturer and racer of motorcycles, it was only natural for Curtiss to wonder how fast he could move on a motorcycle with his V-8. He instructed his workers to construct a frame that could support the weight of the engine. The Curtiss V-8 was air-cooled, producing approximately 30 to 40 horsepower at 1,800 rpm. The motorcycle used direct drive because a conventional chain-and-belt transmission could not withstand the power of the massive engine. Curtiss took the motorcycle to the Florida Speed Carnival at Ormond Beach in January 1907. He recorded a record-setting speed of 218 kph (136 mph) during his run. He was dubbed "the fastest man on Earth."

Before achieving fame in aeronautics, Glenn Curtiss started his career with motorcycles. He began developing motorcycle engines in 1902. The first was a single-cylinder model generating 3 horsepower. In 1903 he designed an 8-horsepower V-twin engine. These models were followed by four-cylinder in-line engines ranging from 15 to 25 horsepower. In 1906 Curtiss designed his first V-8 engine in response to several requests from early aeronautical experimenters for powerplants for both lighter- and heavier-than-air aircraft.

The early aviation community was beginning to seek out Curtiss because of his growing reputation for designing powerful, lightweight motorcycle engines. As a manufacturer and racer of motorcycles, it was only natural for Curtiss to wonder how fast he could move on a motorcycle with his V--8 engine. He instructed his workers to construct a frame that could support the weight of the engine.

The frame measured nearly 2.4 m (8 ft) in length and the overall weight of the machine was 125 kg (275 lb). It was a prototype built exclusively for the Curtiss V-8 engine. Because of the size of the engine, the seat was mounted behind the power plant so that the rider would not get burned. This in turn necessitated extra long handle bars, which made steering awkward. It used an automobile rear wheel and a motorcycle front wheel. The tires were manufactured by B.F. Goodrich. The machine was not equipped with any suspension system at all. Only the small springs on the seat cushioned the operator's ride. Needless to state, the ride was anything but smooth.

The Curtiss V-8 engine was air-cooled, producing approximately 30 to 40 horsepower at 1,800 rpm. The motorcycle used direct drive because a conventional chain-and-belt transmission could not withstand the power of the Curtiss V-8. The motor was mounted with the crankshaft running lengthwise and was connected to the drive shaft with a double universal joint. A large bevel gear on this shaft meshed with a similar one on the rear wheel.

The engine had two carburetors, each one supplying four of the eight cylinders on each side. There was no choke. The transmission was direct drive, with no clutch. The F-type cylinders were cast of special hard gray iron that was very durable. They were carefully ground and lapped to ensure near perfect compression. The cylinders were set at 90 degrees and were of two-piece design. They had a bore of 3 5/8 inches and the stroke was 3 1/4 inches. The head and pistons were also cast iron. The crankcase was of aluminum. Each of the pistons was fitted with four rings. The intake valves were automatic, atmospheric operated. The exhaust valve was push rod-operated from the camshaft. Curtiss used strong forged alloy steel for the internal components. The individual thin-wall cylinders and the head were attached to the crankcase with high tensile nickel alloy steel studs, contributing to the better-than-average lightness of the overall engine.

Jump spark ignition was used, energized by dry cell batteries. Lubrication was achieved by a splash system. The oil tank was located in front of the seat, holding approximately one liter (one quart) of oil. Fuel capacity was approximately 9.5 liters (2.5 gallons).

Curtiss took the motorcycle to the Florida Speed Carnival at Ormond Beach in January 1907 to make a run with the V-8. The judges agreed upon a two-mile run to get up to speed, one mile for the actual test, and two miles to stop the motorcycle. The machine's braking system was minimal, looking like something that would be found on a geared bicycle. It was a hinged paddle device on the rear tire, which did not permit a quick stop. Tom Baldwin and "Tank" Waters, who traveled with Curtiss, positioned themselves on either side of the machine and pushed the motorcycle until the engine started. Curtiss recorded a speed of 218 kph (136 mph) during the run. He was dubbed "the fastest man on Earth."