The TRX engine was derived from that in the Yamaha TDM850, but the TRX is lighter, lower and sportier than its TDM stablemate. The parallel twin engine produces some 85 Nm of torque and 79 bhp. The engine has five valves per cylinder, three inlet and two exhaust; the inlets are 26mm the exhausts 28mm. Unusually for a dry sump design, the oil tank is not remote, but is integral to the engine, sitting atop the gearbox. This feature simplifies manufacture, eradicates external oil lines, and gives faster oil warm-up. 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 in 1996, after which time the TRX and the TDM shared the same engine and transmission. The engine has a balance shaft to smooth out residual vibrations.