Yamaha TX750

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Yamaha TX750
Yamaha tx 750 juin 1973.jpg
1973 Yamaha TX750
Manufacturer Yamaha Motor Company
Parent company Yamaha Corporation
Production 1972-1974
Engine 743 cc (45.3 cu in) SOHC parallel twin
Top speed 95 miles per hour (153 km/h)[1]
Power 63 horsepower (47 kW) @ 7,500rpm[1]
Transmission Five speed sequential
Weight 235 kilograms (518 lb) (wet)
Related XS650

The TX750 was a Yamaha motorcycle made in 1973 and 1974. It was loosely based on the XS650 but had what Yamaha called an "Omni-Phase balancer" to counter vibrations which are inherent in a parallel twin with the crankshaft set at 360 degrees (both pistons rise at the same time). Using a pair of balancers (one to stabilize the imbalance of the cylinders, the other to counter the rocking caused by the first balancer), Yamaha’s Omni-Phase balancer essentially eliminated vibration in the TX750, producing a smooth ride previously thought possible only in a triple or a four cylinder.[2] This new system was a first for a motorcycle but resulted in massive failures for the first model year. Although, these problems were fixed in 1974 sales never picked up and the machine was shelved.

Reception[edit]

Cycle World magazine, in their October 1972 issue positively reviewed the concept when they wrote: "The result is smoothness beyond belief," . "Shut your eyes and you are on a four. It couldn’t be a twin." In addition, the bike was set up with a single front disc brake with provision to install a second one on the other side. European machines were delivered with twin disc brakes from the factory. The bike also had an interesting warning light system with a brake pad wear indicator, a first for a motorcycle.

Reliability Problems[edit]

The bike was popular at first but soon reliability problems began to emerge and the problems lay with the Omni-Phase balancer: At high rpm the balance weights would whip oil in the sump into a froth, aerating the oil and starving the crank for lubrication which resulted in bearing failure.[3]

In addition, the balance chain would stretch, resulting with the counterweights being out of phase and making the engine run rough. Although Yamaha quickly repaired the problems, including a deeper sump and an adjustable balance chain, sales fell and the TX750 became synonymous with poor design and reliability. The 1974 Model was extensively modified with a revised sump and does not suffer from reliability issues.[citation needed]

References[edit]

  1. ^ a b Holliday, Bob (1974), Motorcycle panorama: a pictorial review of design and development, Newton Abbot, p. 108, ISBN 978-0-668-03647-4 
  2. ^ Richard Backus (November–December 2008). "1973-1974 Yamaha TX750". Motorcycle Classics. Retrieved 2009-08-10. 
  3. ^ Richard Backus (November–December 2007). "The Yamaha TX750". Motorcycle Classics. Retrieved 2011-10-04.