Yamaha TZ 750

The Yamaha TZ750 was a series production two-stroke race motorcycle built by Yamaha to compete in the Formula 750 class in the 1970s. Motorcyclist called it "the most notorious and successful roadracing motorcycle of the 1970s". Another journal called it the dominant motorcycle of the era, noting its nine consecutive Daytona 200 wins, starting in 1974.

Another triumph of note was when Joey Dunlop rode to victory in the 1980 Classic TT during the process of which he upped the lap record on the Snaefell Mountain Course to an average speed of 115.22 mph (185.43 km/h). This is also the fastest recorded lap of the Mountain Course by a Yamaha 750cc two-stroke machine.

It was rated by journalist Kevin Cameron as one of the five most influential motorcycle designs: its monoshock suspension, high-strength frame and wide tires were necessary to handle the high engine output, and became standard for sportbikes.

Twin TZ750 engines powered the Silver Bird motorcycle land-speed record setting streamliner motorcycle, the first to break 300 miles per hour (480 km/h).

Source Wikipedia

The official Yamaha 350 racer, Jarno Saarinen, rode to victory in the 1973 Imola 200 Miles after having won that year's Daytona 200. It was at the Imola race that motorcycle fans first got word of the four-cylinder Yamaha 700, a new speed demon that had been built by the most famous manufacturer of international racing motorcycles to challenge the Suzuki and Kawasaki three-cylinder 750s.
Saarinen was responsible for the publicity leak, although it was not all that indiscreet. The new Yamaha engine consisted of two 350-cc. racing engines put together. In tests it generated 140 h.p.

The Yamaha 700 was tested secretly on the company's own track. Giacomo Agostini, who had joined the team, tried it out first after the test driver Hideo Kanaya had tuned it. Agostini had switched to Yamaha chiefly to race formula 750 in the United States. He rode the new 700 to win the 1974 Daytona 200 Miles and the Imola 200, sister race of the Daytona. From that moment on, the 750 class throughout the world was the exclusive property of official and private riders of the Yamaha, except for occasional sorties by Kawasaki and Suzuki.

At first the four-cylinder 700 had an engine built by putting together a pair of two-cylinder Yamaha 350s with gill-port distribution. The engine generated some 115 h.p., making possible a top speed of about 185 m.p.h. The chassis had the classic double cradle with traditional suspension. Altogether the motorcycle weighed over 350 pounds, which was too much for a racing motorcycle. Agostini tried out an interesting chassis modification in order to improve the vehicle's maneuverability and stability.

A rear suspension with triangulated Yamaha 700 Four-cylinder swinging fork was installed. The upper arm worked the single central shock absorber, which was mounted in a semihorizontal position under the fuel tank.

The new type of suspension, called "monocross" or "cantilever," was installed on all subsequent Yamaha racers. In 1975 the TZ 700 became the TZ 750. It was not a question of merely increasing displacement, but involved an overhaul of both the engine and the chassis. The Yamaha Daytona had always looked bulky and clumsy, but after this overhauling it looked sleek and powerful.

The Yamaha TZ 750 was unbeatable in formula 750 racing. Suzuki and Kawasaki turned out new models without being able to overtake it.

Until the end of the 1976 season, Cecotto, Roberts, Romero, Agostini, and Victor Palomo—FIM formula 750 champion in 1976—rode official, private, or partially-assisted Yamaha TZ 750s. Thanks chiefly to its mechanical robustness and its 140 h.p., this motorcycle dominated the major speed races.

Motorcycle: Yamaha TZ 750 (model OW 31, official 1976 version) Manufacturer: Yamaha Motor Co. Ltd.,
Type: Daytona and FIM formula 750 Year: 1976
Engine: Yamaha four-cylinder in-line, two-stroke, with cross-port distribution. Displacement 750 cc. (66 mm. x54 mm.)
Cooling: Water
Transmission: Six-speed block
Power: About 140 h.p. at 10,700 r.p.m.
Maximum speed: Over 185 m.p.h.
Chassis: Double cradle, continuous, tubular. Front, telescopic fork suspension; rear, cantilever telescopic suspension
Brakes: Front, double hydraulic disk; rear, single hydraulic disk