TALE OF THE TAPE: VERY OLD v VERY NEW

Motorcycle News (UK) - - Features -

1985: head­stock height 894mm 2016: 759mm

The new bike is wind tun­nel tested, and also car­ries a lot of ex­pe­ri­ence gained in rac­ing. The big dif­fer­ence is frontal area: the 2016 bike steer­ing head is 139mm lower, and the top of its front tyre is 16mm nearer the ground too. It’s also got a faired-in head­light, lower screen, and 21mm higher seat, which cleans up the air flow over your back when you’re crouch­ing down.

1985: cra­dle frame, air­box be­hind carbs. 2016: beam frame, air­box above in­jec­tors

De­spite the F’s im­pact when it first ap­peared, its over­all de­sign faced more back­wards than for­wards. The frame used a rel­a­tively new ma­te­rial – alu­minium – but was still de­signed as a cra­dle to house the en­gine, rather than a means to trans­mit steer­ing in­puts from the head­stock to the swingarm pivot. And the en­gine was re­stricted by a tra­di­tional in­take path brought about by a hemmed-in air­box and up­right carbs. Yamaha’s 1985 FZ750 had al­ready solved both these prob­lems.

1985: 41mm damper rod 2016: 41mm usd Big Pis­ton

By 1985 it was com­mon knowl­edge that fork tubes needed to be stiff. The snag was mak­ing them so. The old bike’s con­ven­tional legs re­lied on 41mm steel tubes to re­sist bend­ing un­der brak­ing. To­day’s bike also has 41mm tubes, but in an up­side down de­sign. The brak­ing forces are largely han­dled by 50mm alu­minium outer tubes, car­ried much closer to the ground so they bend less.

1985: 24.75° 2016: 23.95°

Another sur­prise: the elec­tronic pro­trac­tor shows the two bikes are within 0.8 de­grees of each other. The old GSX-R was pretty rad­i­cal for its day. Its big front wheel kept it calm most of the time, but it could get slappy. The new bike, equipped with a steer­ing damper, is far more sta­ble. The new GSX-R isn’t just shorter, stiffer, lighter and more di­rect; all the de­tails are bet­ter too. We in­ves­ti­gated the in­ter­nal fric­tion in both bikes’ forks. The trick is to mea­sure the length of the ex­posed chrome leg twice – once af­ter push­ing the forks down and let­ting them re­turn, and again af­ter lift­ing them up and let­ting them re­turn. The dif­fer­ence in the two fig­ures (any­thing un­der 8mm is good) gives an idea of the in­ter­nal fric­tion. Sur­pris­ingly there wasn’t much in it: 5.5mm new, 4.1mm old. That speaks vol­umes for Nathan

Colombi’s re­build.

One GSX-R is rock steady, the other isn’t. We got out the tape mea­sure to dis­cover why

1985: 529mm 2016: 583mm

Back in 1985, if a swingarm was alu­minium that was al­most enough. It wasn’t un­til 1994 that Suzuki added sig­nif­i­cant brac­ing. To­day, the L6 uses pre­ci­sion cast­ing to cut weight and add stiff­ness. It’s also 54mm longer, even though the wheel­base is 37mm shorter. That’s be­cause the new bike has an in­clined en­gine with a stacked gear­box, to min­imise its front-to-rear length and get weight for­ward. A longer swingarm re­acts less to chain pull forces, help­ing sta­bil­ity. You can gun the L6 banked over on bumps and it stays com­posed.

1985: 1427mm 2016: 1390mm

You would think the F, with its 37mm longer wheel­base, had more sta­bil­ity. But the L6 beats it by hav­ing shorter load paths through the (far stiffer) chas­sis and wheels, higher qual­ity sus­pen­sion and vastly su­pe­rior tyres.

1985: 719mm in front of rear con­tact patch, 513mm above ground 2016: 727mm, 548mm

Cen­tre of mass is the point through which all the forces on the bike can be said to act. It has a crit­i­cal ef­fect on trac­tion (as the bike pitches un­der brak­ing or ac­cel­er­a­tion) and sta­bil­ity. A typ­i­cal mod­ern sports­bike’s c of m (with a full tank) is level with the rear wheel rim, and slightly for­ward of half way be­tween the axles. Adding a rider raises it level with the rear tyre, and nearer the cen­tre.

The 1985 GSX-R’S c of m is sur­pris­ingly close to the lat­est bike’s. But there is a dif­fer­ence: the new bike uses ex­pe­ri­ence de­vel­oped in the early Mo­togp years to clus­ter most of the heavy stuff near the cen­tre of mass. The old bike is a lot more spread out. You feel it in­stantly when you try and change di­rec­tion quickly. The new bike can do it; the old bike can’t.

1985: 10,500rpm/83bhp 2016: 13,200rpm/130bhp

The two bikes share a bore and stroke of 70mm x 48.7mm. Suzuki tried a 73mm bore in 1988/89, and 72mm in 1996-2005, but oth­er­wise they’ve stuck to the orig­i­nal di­men­sions. So how did they get 26% more revs? Lighter com­po­nents. Grad­u­ally, by shav­ing a few grams here and there, a fac­tory can re­duce the mass of the key mov­ing parts – valves, pis­ton and con­rod – so they can be ac­cel­er­ated and de­cel­er­ated more quickly, and still stay re­li­able. Apart from ti­ta­nium valves in the new bike, the ma­te­ri­als for the other two com­po­nents have hardly changed in 30 years.

Ru­pert Paul and Bruce Dunn mea­sur­ing up the vi­tal sta­tis­tics Aero­dy­nam­ics Brutish and ag­gres­sive, it’s still a sexy beast Ba­sic lay­out King of the acro­nym, full floater doesn’t sound so ap­peal­ing though Fork de­sign Clas­sic white-faced clocks for the first

Thor­oughly mod­ern er­gonomics, you can steer it us­ing your core Swingarm Wheel­base Three decades of devel­op­ment and it’s the L6 Cen­tre of mass Sus­pen­sion per­for­mance the old bike could only dream of hav­ing En­gine Beefy usd forks, su­per-slip­pery aero­dy­namic

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