More on Yamaha's 4-stroke GP bike - The YZR-M1 - September 2001

Yamaha has competed in 500 GP since 1973 and was the first marque to win a 500 World Championship with a two-stroke machine two years later in the hands of Giacomo Agostini.

Two-strokes have dominated ever since and Yamaha is still a leading contender, currently fighting for the 2001 World Championship, the last-ever 500 crown before the new regulations for four-stroke is introduced in 2002.

The decision to switch the focus of this category to four-stroke machinery will further enable Yamaha to take the high technologies they develop for the racetrack and integrate them into the products of the future. It’s for this reason Yamaha was deeply involved in this vital transition from the very outset, working with fellow members of the MSMA (Motorcycle Sports Manufacturers Association), Dorna and the FIM, and aims to be ready to win with its all-new YZR-M1 when the contest for the 2002 World Championship begins.

Yamaha officially announced its YZR-M1 four-stroke Grand Prix machine in April 2001, a couple of months after we published the worlds first footage of the machine in action.

The M1 code following Yamaha’s traditional YZR race prototype prefix stands for Mission One. The machine uses an all-new in-line, four-cylinder engine with Yamaha’s enormously successful trademark five-valve head design. The chassis is a direct development from that of the YZR500 two-stroke GP bike, featuring an adjustable head stem and swingarm pivot, the major distinction being the geometry – chosen to ensure the most can be extracted from the four-stroke with its different engine characteristics.

Many configurations were considered when deciding on an engine format for this new category of MotoGP, with Yamaha’s finest engineers concluding that the in-line-four layout offers the best balance of compactness, outright performance and power delivery.

The YZR-M1 commenced its test schedule in Japan last autumn, moving to Malaysia and Australia before commencing a gruelling European programme in May 2001. In June the M1 was the first of the new-generation four-strokes to run in public, when test rider Norihiko Fujiwara rode two demo laps at the Catalan GP in Barcelona.

The YZR-M1’s engine may be of a well-recognised configuration but it is no ordinary in-line four. The new GP regulations permit a maximum capacity of 990cc, which allows excessive power outputs, more than can be effectively used on modern-day racetracks. This made exotic technology such as pneumatic valves unnecessary and the real challenge has been to produce controllable performance, power that works with the rider, the tyres and fuel system that manages consumption efficiently to meet tight fuel limits.

Immediately, there can be a direct link here to street riders who want the safest, most useable, most efficient performance from their motorcycles.

The initial efforts of the Yamaha’s engineers have been focused on harnessing the YZR-M1’s 200-plus horsepower in a linear way that won’t only produce quick one-off lap times but rather a winning pace over full-race distance. This involves painstaking work with the YZR-M1’s sophisticated engine-management system and with Yamaha’s technical partners, especially in the related areas of suspension and tyres.

“With the new four-stroke, we believe that tyre life is the most crucial issue of all,” says Yamaha 500 Grand Prix project leader Masahiko Nakajima. “We are working to produce an engine that looks after its tyres all the way to the finish of races and we are doing a lot of work on tyre development. From this point of view the new formula is a big challenge, because the extra speed, weight and torque of the four-stroke means a lot of extra work for the rubber.”

The super-compact in-line-four engine (10% lighter in weight than that developed for the YZF-R7), chosen specifically to complement overall performance, is housed within a Deltabox chassis that is directly related to that of the YZR500.

For many years the YZR500 has been respected as the best-handling 500, so it has been Yamaha’s desire to instil the YZR-M1 with similar handling and steering characteristics. The two bikes’ chassis are visibly similar, though the M1’s massively braced swing-arm bears testament to the engine’s huge power output.

High-tech software and hardware is also being employed to meet the challenge of reducing the negative effects of engine braking during downshifts, thus improving controllability during deceleration – another innovation that will offer obvious benefits to the street rider.

Following initial shakedown tests in Japan, at Yamaha’s private Fukuroi test track, the YZR-M1 has enjoyed an intensive testing and evaluation programme at tracks in Asia, Australia and Europe.

The YZR-M1 made its international testing debut during December 2000 at Sepang, Malaysia, where Marlboro Yamaha Team 500 stars Max Biaggi and Carlos Checa had their first outings on the bike, alongside test rider Norihiko Fujiwara.

In February 2001 the YZR-M1 ran at Phillip Island, Australia, and after another session at Sepang was taken to Europe for its intensive testing programme.

By this stage Yamaha had also engaged former GP winner John Kocinski as lead test rider for the project. Kocinski, who won the 250 World Championship with Yamaha in 1990 and later went on to win 500 GPs and the World Superbike Championship, has unrivalled knowledge of what’s required from an ultra-high-performance racing motorcycle.

In the hands of these various riders the YZR-M1 immediately met expectations, in both lap times and race-distance endurance tests, showing better acceleration and top speed than the 2001 YZR500 – helped by the improved aerodynamic bodywork. Everyone who tested the bike in these early outings agreed that the YZR-M1 is easier to ride than a 500 because power delivery is so smooth and linear, making an easier machine to drive off the turns.

“Power output is very similar to our current 500 GP bike, with a little more at the very peak, around 15,000rpm,” explains engine designer Masakazu Shiohara. “But there’s a much wider spread of power and torque output is high, with a very flat curve.”

Nevertheless, development work in Europe has continued to focus on further smoothing and fattening of the powerband, ensuring that the 200 plus horsepower engine looks after its tyres with the greatest efficiency. And, by using new technologies, there has been crucial progress on improving performance during downshifting. Throughout the testing programme the YZR-M1 has proved to be highly reliable, the engine able to cover over 1000km, while running a pace within a fraction of the lap record at each racetrack.

Some of the greatest riders in the world have already ridden the YZR-M1 and all of them have heaped praise upon the machine, now more than halfway through its development programme.

Biaggi first rode the YZR-M1 last December and more recently tested the bike at Mugello, in Italy. “The four-stroke seems to have similar power to the 500, but the character is different,” says the Italian. “The bike doesn’t feel so heavy, a little more than the 500, but not too much. The main thing I’ve been thinking about is the base chassis set-up. It is just a prototype machine at the moment, so nothing is fixed – engine position, weight distribution and so on. The YZR-M1 keeps getting better and it’ll be great when we can focus exclusively on the bike later in the year.”

Unlike Biaggi, team-mate Checa has plenty of four-stroke racetrack experience, because he trains on his own highly tuned R1 streetbike. “I feel better on the four-stroke, more comfortable,” says the Spaniard. “The engine braking doesn’t always help but what you do get is a constant connection between engine, tyre and tarmac, so you have rear traction all the time, so you can feel what’s going on at the rear. The four-stroke gives you more constant pressure on the tyre, and also delivers easier power, unlike the 500 which is sharper.”

Kocinski also enthuses about the YZR-M1’s performance. “It’s a nice bike to ride, Yamaha have done a good job,” says the American. “They’ve got it to a high level very quickly. But racing is never ending – you’re always trying to make things better, so if you’re doing your job, you’re never satisfied. We are very close to the present YZR500 performance but right now we’ve got a little way to go. Five hundreds have been around for years and this bike has only been around for a few months. It’s not easy to beat a 500 – they’re very fast motorcycles, the fastest in the world. You can’t just come in and outperform them straight away, but we’re getting there.

“Yamaha improve the bike every time I test, it’s a big challenge for all of us and I’m enjoying it. There’s a lot of potential there, it’s just a matter of squeezing it out. The power is definitely smooth but there’s one hell of a lot of it.”

We scooped the world with the first footage of the bike way back at the beginning of the year
Some MPEG video released by Yamaha
Low-Res - 800 KB
High-Res - 1.5 MB