Yamaha TRX850

The Yamaha TRX850 is a sports motorcycle with a 10-valve dohc 849 cc 270° parallel-twin engine. Yamaha first released it in Japan in 1995, and a version for the European market became available in 1996. The TRX is lighter, lower and sportier than its stablemate, the TDM850; but in 1999 Yamaha stopped making the TRX, while the TDM series, enlarged to 900 cc, remains in production.

Design and development

The TRX engine has five valves per cylinder, three inlet and two exhaust. It produces some 84 Nm of torque and around 80 bhp. Unusually for a dry sump design, the oil tank is not remote, but is integral to the engine, sitting atop the gearbox. This feature eradicates external oil lines, gives faster oil warm-up, and simplifies manufacture. The shallow sump allows the engine to be sited lower, for an optimal CG position. The 360° crank of the original TDM was changed to a 270° crank for both the TRX and later TDMs. The engine has a balance shaft to smooth out vibrations.The conventional telescopic front forks have clip-on handlebars, and the rear suspension is a rising-rate monoshock unit.