Yamaha TRX850 - Design and Development

Design and Development

The TRX was designed to exploit the 1990s craze for big twin-cylinder sportsbikes, being aimed particularly at the 900 cc Ducati SuperSport V-twin, whose tubular trellis frame it echoed. However, the TRX's price was high and it sold poorly in Europe, being overshadowed by faster and more sophisticated motorcycles such as the Honda VTR1000, Suzuki TL1000S and Ducati 916. In 1999 Yamaha stopped making the TRX, but the TDM, enlarged to 900 cc, remains in production.

The TRX dry sump engine produces some 84 Nm of torque, and around 80 bhp. Uniquely, the oil tank is not remote, but is integral to the engine, sitting atop the gearbox. This design eradicates external oil lines, gives faster oil warm-up, and the shallow sump allows the engine to be sited lower, thereby benefitting the CG position. The 360° crank of the original TDM morphed into a 270° crank for both the TRX and for later TDMs.

Compared to the TDM, the TRX is lighter, lower and sportier. Its front forks are conventional telescopics, while the rear suspension is a rising-rate monoshock unit. Owners often replace the original disc brake calipers with superior Yamaha "Blue-Spot" items. The heavy stock exhaust silencers tend to choke the output; so any TRX benefits from lightweight units. The original-equipment Michelin Macadams were hard-compound tyres that gave poor adhesion. Popular replacement tyres include Michelin Pilots or Pirelli Diablo Stradas.

The TRX was intended primarily as a solo machine, with only the barest provision for a pillion passenger, namely very high pillion foot pegs, a small thin seat, and a token seat strap (rather than a proper grab rail).