MICHAEL ESDAILE: THE ORIGIN OF THE 2009 YZF-R1

Inside MotoGP: The Origin of the 2009 Yamaha YZF-R1: the 2004 MotoGP YZR-M1

For the 2009 model YZF-R1, Yamaha adopted a two-plane (or ‘cross-plane’) crankshaft.  While some poorly-educated scribes refer to this as a ‘big-bang’ engine, it is nothing of the sort.  With the crankpins displaced at even 90 degree intervals, it has irregular firing intervals between each combustion stroke and is something first reported on by MICHAEL ESDAILE in an article he wrote for Kiwi Rider in April, 2005…

YAMAHA, like Honda, was one of the keenest proponents of the four-stroke MotoGP class when it was first proposed as a replacement for the long-standing 500cc class, which had come to be dominated by two-strokes.

In 2001, the Federation Internationale Motocycliste (FIM) established the MotoGP technical rules and Yamaha developed a five-valves per cylinder 990cc in-line four cylinder four-stroke, equipped with carburettors.

This latter feature was a real surprise as all other makers of MotoGP four-strokes adopted electronically controlled fuel-injection. 

The in-line four layout was chosen by Yamaha as the most compact method of building a 990cc four-stroke racer.  The reasoning was that it allowed the engine to be located in what the Yamaha engineers considered the ideal location without a second bank of cylinders getting in the way. 

No doubt the success of Honda’s V5 RC211V made the Yamaha men wonder about the wisdom of the in-line layout, but they stuck with it, switching to fuel-injection in 2003.

However, the record shows Yamaha had little success with the original YZR-M1.  The first season (2002), Yamaha’s lead rider was Massamiliano Biaggi, backed by Carlos Checa.  Biaggi finished second to Honda’s Valentino Rossi, with 215 points to Rossi’s 355 while Checa was fifth in the title chase, amassing just 141 points along the way.

Of some small consolation to Yamaha was the fact Biaggi won the Czech and Malaysian GPs on the new four-stroke – but that was small beer compared to Rossi’s 10 wins on the Honda V5, backed up by a win each for Honda-mounted Alex Barros and Tohru Ukawa.

For 2003, Biaggi switched to Honda power while Brazilian veteran Alex Barros was signed to ride the Yamaha alongside Checa, with Shinya Nakano, Oliver Jacque and Norick Abe also on YZR-M1s.

The results were even more desultory – the best finish being Barros’ third placing in France.  Highest points scorer for Yamaha by season’s end was Checa, seventh on the table with 123 points while Barros was ninth with just 101 points.

Yamaha knew it needed to do something pretty smartly to restore glory to its grand prix effort and its Technology Development Division got to work to give the YZR-M1 a major re-think.

THE BIG CHANGE

While the engineers explored several different options, feelers were extended to Rossi.  Unhappy with what he considered poor treatment at Honda, the Italian eventually switched camps, taking the majority of his pit crew with him.

In January 2004 the Italian and his crew got to work, testing four chassis and engine configurations before settling on the direction he wished to take.  The chassis he chose reportedly had a little less lateral rigidity for more front-end feel at maximum bank angle as well as an inverted swing-arm that saw the reinforcing bridgework on the underside to help lower the centre of gravity.

At the same time, Rossi preferred the engine with a four valve cylinder head (in place of the old five valve layout) and a revised firing order.  In place of the normal two-up two-down crankpin single plane crank used on in-line fours, the Yamaha engineers adopted a two plane crankshaft with the centre two crank-pins arranged 90 degrees apart from the two outside cylinders to provide firing intervals identical to a 90 degree V4, such as the 1988 RC30 Honda.

Rossi found this crankshaft layout, along with the four valve cylinder head, offered a more predictable power delivery and better traction – a point familiar to riders who switched from in-line 750cc fours to Honda’s RC30 V4 in 1988…

For Valentino the advantages were instantly noticeable – a more predictable power delivery, improved tyre wear and better drive, especially in the closing stages of the race.

One feature Rossi also came to appreciate after his first test aboard the M1 was Yamaha’s trademark reverse rotating crank layout.  Put simply the reverse (compared to the rotation of the front and rear wheels) rotating crank partially counteracts the gyroscopic forces created by the front and rear wheels.  On the M1, the reveres rotating crank partially neutralized this force and improved the M1’s turn-in response.  Basically Rossi only needed to think where he wanted the bike to go and it was there, as some of the passing moves he made under brakes highlighted.

THE ROSSI FACTOR

Although there had been a huge advance in the technical package of the YZR-M1, the greatest single advance for Yamaha was Rossi’s signature on a two-year contract.  Winning the first GP of the 2004 season was a huge boost to the technical team at Iwata and one can only imagine the extended celebrations at season’s end when Rossi clinched the MotoGP crown ahead of a phalanx of Hondas.

The next best Yamaha rider in the final points tally was Checa, way down in seventh place on 117 points, while new-comer Marco Melandri was 12th on 75 points, a point ahead of Japanese veteran Norick Abe.

For 2005, Checa went to Ducati, Abe to Superbike racing on a Yamaha YZF-R1 while Colin Edwards joined Rossi.  Meantime Melandri was proving a force after spending a year getting to grips with the 220 plus horsepower, 145 kg Yamaha four-stroke.

On the technical side, for the 2005 season Yamaha slimmed down the engine to improve aerodynamics as well as installing an electronic controlled Idle Control System (ICS) and Traction Control System (TCS).  The former is to reduce engine braking and thus avoid rear wheel hop on the approach to slow corners while the latter is designed to control rear wheel-spin.

In addition, the chassis had been fine-tuned: the swing-arm was longer and the bike rodes higher on its suspension in an effort to get more weight transfer onto the front tyre during braking.

With Honda throwing more resources into its own MotoGP effort, the 2005 season promised to be a titanic battle: Yamaha vs Honda; Rossi vs Sete Gibernau.