RESTORING
Gone from Yamaha’s UK model list after a mere two years, TDRs are now in big demand
Could it be that Yamaha’s TDR250 is more popular now than it was when current in the late 1980s and early 1990s? Certainly that would appear to be the case in the UK, where two-stroke fans now can’t get enough of Yamaha’s quirky Powervalve twin.
Owners desperate to live the TDR experience gladly snap them up, regardless of what territory they were originally sold into. Quite right too, the genius of the TDR250 is now all too apparent.
There was some confusion among the British motorcycling public when the TDR250 arrived in 1988. That was compounded by the contemporaneous availability of the TZR250 2MA; pretty much the same engine in a sportsbike package, aluminium Deltabox frame and all – much more our kind of language back then than the TDR with its tubular steel frame. One brochure said of the 250: “The Yamaha TDR – adding a new dimension to the already exciting field of sport riding.” Fair enough, but it needed a slightly squinty view to see that dimension.
If the TDR250 was meant to be a trail bike, it lacked a little focus. That despite Yamaha specifying a trail style chassis and lowering the parallel twin engine’s first gear for better dirt tractability – with the commensurate benefit of snappier acceleration on the road – and fitting a crossover high-level exhaust expansion to give better low and mid power delivery with good ground clearance. The Mikuni TM28SS carbs were rejetted to match the pipes and different airbox. Crankcase induction was via reed valves. The liquid-cooled engine had its two-stroke oil supplied by Yamaha’s established Autolube system. Power output was a claimed 49bhp at 10,000rpm. There was a 240cc version for the French market.
Yamaha used what it called an ‘orthogonal’ arrangement of engine mounts to minimise vibration. The same theory was applied to the TZR; ‘orthogonal’ describes a layout placing the mounts at right angles to one another.
The TDR could claim a world first with its combination of a CDI ignition with a digital advance system. This 4-bit microprocessor system also controlled the all-important YPVS set-up.
Chassis-wise, the tubular steel frame had a high headstock for long air-assisted forks with decent travel of 160mm. Castor angle of 27° and 114mm trail made for a short wheelbase and quick steering, even with a chunkily shod 18-inch wire-spoked front wheel. Rear was 17-inch. Yamaha’s Monocross suspension featured at the back, again with long travel, this time 150mm. The box-section swingarm was aluminium for Japanese domestic market bikes while the rest of the world got steel.
Brake discs were the same size as the TZR with the TDR having a single 320mm
