Yamaha 850SS, any­one?

Practical Sportsbikes (UK) - - Yamaha Trx850 -

SINCE THE ar­rival of thetdm850 in 1991 there had long been spec­u­la­tion about the cre­ation of a sports­bike with the same twin cylin­der en­gine. But it took the cre­ation of a one-off spe­cial to spuryamaha into ac­tion.

The ‘850 Su­per Twin’ was cre­ated by lead­ing Ger­man mag­a­zine Mo­tor­rad and was es­sen­tially an FZR600 fit­ted with ATDM850 en­gine from parts do­nated byyamaha them­selves.the fac­tory then con­firmed its in­ter­est by tak­ing the bike to its Euro­pean base in­am­s­ter­dam for fur­ther eval­u­a­tion.

Af­ter this, in the au­tumn of 1994, ru­mours of an of­fi­cial sports TDM850 be­gan to gather se­ri­ous pace, es­pe­cially when a pro­to­type mule was spot­ted un­der­go­ing test­ing in the south of France.

Even so, when first launched in 1995 the TRX850 was never in­tended as a Euro­pean model, and was first sold only in Ja­pan.

On face value it was a bliss­fully sim­ple idea: takeyamaha’s per­for­mance twin en­gine, bolt it into a semi-sport­ing road chas­sis with lots of cost cut­ting via raid­ing the parts-bin and voila – a ‘Yamaha 850SS’.

In re­al­i­tyyamaha got a lot closer to the Ital­ian than that rather sim­plis­tic ap­proach sounds, cour­tesy of two vari­a­tions. Firstly, rather than use its own trade­mark ‘Deltabox’ twin-spar alu­minium frame (as the Ger­mans had done with the Su­per Twin),yamaha’s en­gi­neers pretty much copied the tubu­lar steel trel­lis-type frame which had be­come a Du­cati trade­mark.the re­sult, at first glance at least, left no one in any doubt about which ma­chine the new Yamaha was as­pir­ing to beat.

Sec­ond, and prob­a­bly more im­por­tantly still, thetrx’s five-valve, par­al­lel-twin mo­tor wasn’t ‘just’ that of the TDM850. In­stead, it had been sig­nif­i­cantly and clev­erly re­worked with a new 270º crank­shaft (in place of the TDM’S 180º) to give a lumpier sound and feel more akin to that of av-twin – a prac­tice that’s widely copied to­day.

The re­sult was im­pres­sively ef­fec­tive: twist the throt­tle of theyamaha and you’d be for­given for think­ing you were aboard a Du­cati SS shud­der­ing through its char­ac­ter­is­tic rough spot be­tween 3-5000rpm.above that, a bal­ancer shaft smoothed out vi­bra­tions as the Ja­panese twin fired up to its 8000rpm red­line. Else­where, how­ever, thetrx’s de­sign was more

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