GP1 technology: Yamaha YZR-M1

GP1 technology: Yamaha YZR-M1

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A new four-stroke in-line engine in the tried and tested chassis of the 500cc two-stroke machine: With this combination, Yamaha can stir up the GP1 World Championship from next season?

Hand on heart: The Yamaha concept for the GP1 World Championship 2002 didn’t exactly knock the true technology freaks off their feet.

An in-line four-cylinder four-stroke engine in the modified chassis of the 500cc two-stroke engine? that didn’t seem to be the most creative solution for the new challenge in the premier class of motorcycle racing. Honda, on the other hand, provided a real wow experience with the presentation of the V5 prototype.
For a long time, Yamaha also kept the heart of the racer known as the YZR-M1 secretly hidden behind the black paneling, which opened the door to speculation. Rumors kept popping up that the engine for the new high-tech world championship would only be an offshoot of the R1 engine. But now the covers have finally fallen. And lo and behold, a compact, very flat new design came to the fore, which has only the most important key data in common with the series engine: four cylinders in line, two overhead camshafts, five-valve technology, wet sump lubrication and electronic fuel injection. Otherwise the GP1 engine differs fundamentally from the well-known four-stroke engines from the Yamaha sports program.
Particularly noticeable is the fully milled motor housing, which has a very specific peculiarity. The parting line at the level of the crankshaft runs at an angle of 45 degrees to the rest of the housing and thus indicates a mounting option that was already common to the legendary MV Agusta racing machines. After loosening the housing screws, the upper part of the housing including the crankshaft and the complete engine can be separated from the lower part with the complete power transmission. What does this solution mean in racing practice with the cylinders separated from the housing in contrast to the R1? Not only can the engine be swapped quickly, but Yamaha can also use engines with different bore-to-stroke ratios, depending on the race track. The ultra-short cylinders of the GP1 engine currently suggest an extremely short stroke of around 40 millimeters, which is also necessary in order to be able to mobilize significantly more than 200 hp at speeds of around 15,000 rpm.
When driving the two overhead camshafts, Yamaha does not use the gear technology common in racing engines, but relies on a combination of two gear wheels and a short timing chain. This drives an intermediate gear in the cylinder head, which sets the two camshafts in rotation. The small gears enable the small valve angles that are important for a compact combustion chamber. Typically Yamaha, the GP1 engine also has three intake and two exhaust valves per cylinder. The power is transmitted via the dry clutch, which is mandatory for racing purposes, and a cassette gearbox that allows the wheelset to be changed even with the engine installed.
The elaborate but extremely compact engine brings despite the larger displacement – according to its own information, Yamaha does not fully exhaust the limit of 990 cm3 allowed in the new GP1 World Championship? around ten percent less weight than the 750cc engine of the superbike R7. The lambda probe located in the collector of the titanium exhaust system is also noticeable. It helps to analyze the mixture composition and to regulate it accordingly and paves the way for a catalyst that may be prescribed in the future.
The chassis with the obligatory bridge frame made of welded aluminum sheets with adjustable steering head angle and swing arm mounting, the upside-down fork and the suspension strut from Öhlins with titanium spring largely corresponds to the current 500 Grand Prix motorcycle, which is known for its good handling. The radially screwed Brembo monobloc four-piston brake calipers on the front wheel or the Marchesini magnesium wheels, which are used in both 17 and 16.50 inches at the rear, also come from the YZR 500 collection. The voluminous banana swing arm alone carries it the higher weight and the increased power of the GP1 engine. The comparatively generous engine braking torque of the four-stroke engine is to be reduced when downshifting by means of electronic and mechanical solutions that are later also planned for street motorcycles.
S.The carbon fiber material is almost a matter of course for the 24-liter tank as well as for the cladding and seat. All these measures help to keep the weight at the prescribed limit of 145 kilograms and thus to be competitive in the GP1 World Championship from the start. Which does not seem to be just a dream of the Yamaha strategists, as the previous test program with Max Biaggi, Carlos Checa, John Kocinski and the Japanese factory drivers shows. The powerful M1 racer has already survived more than 1000 kilometers at racing speed, achieved record lap times in Brno and a full ten km / h more top speed than the 500 on the short home straight. In preparation for the new World Cup, Yamaha is currently clearly in pole position ?? simple solutions are usually not the worst.

Short test in Suzuka

While the Yamaha Grand Prix stars Max Biaggi and Carlos Checa have been testing the M1 four-stroke machine for months, it was not until the beginning of August before the Honda five-cylinder GP1 racer was driven by a current World Championship driver for the first time. Of course, this honor was reserved for Valentino Rossi (photo), the superstar of the Japanese brand and top favorite of the 500 World Cup. But Rossi’s GP1 maiden voyage in Suzuka, Japan, which took place two days after his victory in the eight-hour race there, was adversely affected by bad weather. Due to heavy rain, the Italian was only able to do a few laps with the RC 211 V. Nevertheless, Rossi was very impressed by the V5 prototype with a displacement of 990 cc: “I think that the four-stroke machine will soon surpass the two-stroke engine. The new GP1 engine has a hell of a lot of power and the bike is a lot easier to ride. However, we are only at the beginning of development and will have to do a few more tests before the new motorcycle is competitive and we can tap the great potential that the concept has. ”In October, Honda wants the RC 211 V on a European racetrack for the first time try out.

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