TDM850 and TDM900 Are Separate Generations
Yamaha developed the TDM850 as a road-focused sports tourer for changing European mountain-road surfaces. Yamaha’s history describes the original model as using an enlarged version of the XTZ750 Super Ténéré parallel twin with a 360-degree crank, downdraft carburetors, a steel Deltabox frame and a wide-ratio five-speed transmission. Yamaha’s technical history records a major 1996 TDM850 evolution to a 270-degree crank, so even first- and second-generation 850 applications should not be combined without checking the year.
For 2002 Yamaha introduced the TDM900 as a full model change. The 897cc generation added fuel injection, a six-speed transmission and an aluminum frame. These are substantial platform changes, not a simple displacement increase. A service item may be explicitly cross-listed between an 850 and 900, but that one listing does not make their engine, induction, brake, chassis or electrical systems interchangeable.