Technology: New super athletes


Technology: New super athletes

The three question marks

Three new ones, three unknowns. The sporty roars of the millennium season could be the Honda CBR 900 RR, Honda VTR 1000 SP-1 and Suzuki GSX-R 750. What makes the three of them potential high-flyers?

Super athlete. Low weight, high engine power, easy handling ?? Properties that cannot easily be reconciled. For this reason alone, the Columbus Superbike egg is likely to remain undiscovered in 2000. However, three completely different newcomers could come a big step closer to the ideal: the Honda CBR 900 RR big bike with an unconventional frame layout, the slim superbike replica Honda VTR 1000 SP-1 and the completely redesigned superbike base Suzuki GSX-R 750. The manufacturers propagate excellent aerodynamics and consistent for all three
Lightweight construction. In terms of dry weight, the CBR and GSX-R want to set class records with 170 and 166 kilograms and are hardly removed from the minimum permitted weight of a racing superbike (162 kilograms). The two owe their flyweight to many optimizations, such as thinner-walled, hollow camshafts, housing covers made of magnesium alloy or even fully electronic and thus light instruments. While the CBR drives elaborate titanium manifolds for a walk, the Suzuki relies less on exotic materials in detail, but on narrower rims, a brake system with only four brake pistons per caliper or even narrower triple trees.
With a dry weight of around 200 kilograms, the VTR-SP is on par with other sports twins, but it still disappoints expectations. But further weight optimization would probably have raised the price above the magical 30,000 mark limit? after all, the elegantly equipped SP should remain affordable and suitable for everyday use. It carries voluminous stainless steel silencers and offers space for two passengers. Quite likely that after a consistent upgrade to a racing motorcycle with light wheels, an adequate exhaust system, single seat and light tank, it should not only be light in accordance with the regulations, but also be perfectly balanced. Apart from that, it is much more that decides at the regulars’ table
Power. With a nominal 136 hp, the VTR sets a new V2 record, comparable to the record-breaking 140 horses of the Suzuki GSX-R 750, which with a nominal 187 hp per liter even slightly exceeds the liter output of the previously dominant 600 class. Another record? Well, the CBR 900 lets 152 mounts gallop (the performance of the German version has not yet been determined) and tops all other 1000s. But sheer performance says less than that
Performance weights, determined with a weight gain of 100 kilograms each for 18 liters of fuel and a fully equipped normal driver. How many kilograms does a horse have to accelerate with the new ones? 1.77 for the CBR, 1.9 for the GSX-R and 2.2 for the VTR. For comparison: A 170 HP World Championship Superbike with 24 liters of fuel at the start weighs 1.58 kilograms – no production motorcycle has been as close as the CBR, which gives hope for enormous acceleration. All three blow by elaborately programmed
Manifold injection gasoline into the intake ducts, the two four-cylinder with one each, the VTR with two injection valves each. Interesting: While Honda arranges the injectors of the CBR at an acute angle to the intake port, Suzuki returns to a larger angle. In addition, the Suzuki technicians put a second upstream of each throttle valve, which a servomotor opens via engine management depending on the operating status. This is to cultivate the throttle response and increase the torque at low speeds. The Honda CBR 900 RR, on the other hand, uses other measures to trim its performance curve. One flap in the airbox varies the air supply depending on the load and speed, while another in the collector of the exhaust system changes the cross-section, also depending on the current operating status. The VTR strengthens its performance curve with a flap in the airbox inlet (see photo on page 43), which regulates the air supply depending on the speed. But first and foremost, the performance arises in the
Engines. Here the trend is towards even lower oscillating and rotating masses, here the trend towards increasingly extreme stroke / bore ratios is stalling. Only the VTR draws level with the so far most radical V2 of the Aprilia mille SP, while the CBR and GSX-R show comparatively conventional relationships. The straight design of the intake ports and increasingly compact combustion chambers due to increasingly acute angles between the intake and exhaust valves (identical for the CBR and GSX-R) are also evolutionary. Straight ducts, in turn, require long valve stems that are continuously acted upon by bucket tappets. Material development helps here as well as with other highly stressed assemblies. Thin-walled forged pistons oscillate in all three engines, while the Honda bushes made of sintered aluminum alloy and the Suzuki galvanically applied treads to the aluminum cylinder ensure wear-resistant friction pairings with good heat transfer. A treat on the VTR engine: a particularly high-speed camshaft drive that is suitable for racing using gear wheels. All motorcycles strive to be extremely compact, way ahead in the
Engines placed under the chassis, which put weight on the front wheel and allow long swinging, which improves controllability. We have three very compact aluminum bridge frames with large cross-sections for the greatest possible rigidity, but with three different mounts of the extremely rigid swingarms: completely conventional in the frame on the GSX-R, supported on the frame and motor on the VTR-SP-1 ?? according to Honda for the purpose of the greatest possible torsional rigidity – separated from the frame only in the engine in the CBR (see photo on page xx), this time with the astonishing reason that a certain flexibility improves controllability. Well, we’ll see. Both Hondas, now finally also the CBR, roll on 17-inch rims at the front, both decelerate with huge braking systems (CBR: 330 millimeter disc diameter). Tighter and more complex spring elements across the board? consistently with upside-down fork and shock absorber with integrated expansion tank – should suffice for the increased sportiness, so that a decrease in damping during racing is hopefully a thing of the past. It is very interesting that the basic chassis data such as wheelbase, caster and steering head angle are again more moderate and apparently everything is done to load weight onto the front wheel. Well. And the
M.orally? Quite simply: A generation of super athletes is approaching us that will remain affordable despite the elaborate construction and consistent design. Does it keep everything that it promises? Let’s see, MOTORRAD is looking forward to a hot test winter.

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