The start of something great: Yamaha’s first V4 MotoGP bike!

Roberts liked the 0W61 V4’s power delivery but the bike was a nightmare to ride anyway, because the crankshafts were too light, so whenever the rear tyre broke traction the engine revs took off, spinning the tyre.

Crankshaft weight has a huge effect on race-bike dynamics: too light and the rear tyre will spin up too easily, too heavy and the bike won’t turn well.

The 0W61’s traction problem was exacerbated by a radical and too-clever-by-half rear suspension system.

Its rear shock was mounted horizontally across the machine, to make the best use of available space and allow the best routing for the exhausts from the rear cylinders of the vee. This was a nice idea, but too many linkages were required between frame and swingarm, drastically reducing the shock’s effectiveness.

And then there was the frame itself… a combination of square-section aluminium tubing (which had been all the rage for a few years) and larger sections that offered little longitudinal rigidity, which would’ve contributed to the bike’s habit of getting horribly out of shape while accelerating away from corners.

Remember that the early 1980s was a period of great experimentation, with chassis engineers still searching for answers to problems that were getting bigger as engines became more powerful and tyres offered more grip.

Roberts only scored a single victory on the 0W61 – the Spanish Grand Prix at Jarama – which he considered one of his greatest successes, because the bike was so difficult to ride. But like he used to say, “What doesn’t kill you, makes you stronger”.

Yamaha engineers learned plenty from the 0W61 to become much stronger. They went back to the drawing board and reemerged from their design shop in early 1983 with the 0W70 V4. This machine was a big improvement and played a starring role in Roberts’s nail-biting head-to-head battle for the ’83 MotoGP crown with Honda’s Freddie Spencer.

Roberts vs Spencer is still arguably the greatest MotoGP duel of all time

Its frame was much stronger, with aluminium spars running from the headstock all the way to the swingarm pivot. Yamaha engineers didn’t know it at the time, but they were pioneering a concept that still reigns supreme in MotoGP: the twin-spar aluminium frame.

“When they started stiffening everything up, I could go faster and smoother for longer,” says Roberts.

In fact, although Yamaha pioneered the twin-spar frame in the premier class, its engineers had nicked the concept from Spanish engineering genius Antonio Cobas, who built a twin-spar chassis for his 1982 Kobas, ridden by future 250cc world champ Sito Pons. Cobas’s creation was essentially an adapted monocoque, because a full monocoque would make the bike pretty much impossible to work on.

After the handling nightmares of 1982, the 0W70’s rear suspension was of conventional design and had another upgrade, from a Yamaha shock to an Öhlins unit, a first in MotoGP. The Swedish suspension company had worked miracles for Yamaha’s factory motocross bikes, so it made sense to bring their expertise into road-racing.

“As soon as I started working with Öhlins they began talking low-, medium- and high-speed on bump [compression damping] and the same on rebound,” said Roberts in Colin Mackellar’s excellent book Yamaha. “I could say, ‘I think this one needs a little less rebound high on top because in fast corners it’s tying me down a bit’, and it meant something to them. It was like heaven.”

The Roberts-versus-Spencer battle raged all season, ebbing and flowing between the two Americans as they rode harder and harder, while their engineers kept marching forward with engine and chassis upgrades. Roberts’ V4 had more power while Spencer’s brand-new, three-cylinder NS500 was nimbler. Their battle is still arguably the greatest MotoGP duel of all time.

In the end, it all came down to two corners – the right-handers that lead onto and off the back straight at Anderstorp, venue for the Swedish GP, penultimate race of the year.

Both riders knew that every point counted, so when they arrived at the end of the back straight on the last lap they both went deeper into the corner than ever before. Spencer out-braked Roberts and both ran off the track, Spencer winning the scramble to the finish line.

The three-point difference between first and second eventually decided the title in Spencer’s favour, by just two points from Roberts, who still doesn’t like to talk about what happened at Anderstorp.

Although Roberts blames Spencer for the incident, Roberts’ crew chief Kel Carruthers sees it differently.

“It was the mistake Kenny made at the corner going onto the back straight,” says Carruthers. “If he had done that corner right, Freddie wouldn’t have been on his tail at the end of the straight and Kenny would’ve won the championship.”

The disgruntled Roberts retired from GP racing at the end of the season — a year too early because Yamaha finally built another good 500 for 1984.

The 0W76 took Lawson to the 1984 title and was the basis of the machines that won the 1986 and 1988 titles with Lawson and the 1990, 1991 and 1992 crowns with Wayne Rainey.

There were two 1984 developments in particular that transformed Yamaha’s V4 into a championship-winning motorcycle.

First, the engine. Yamaha switched from rotary-valve induction to reed-valve induction. The company had popularised reed valves in the 1970s, because reeds softened the power delivery of hard-to-handle two-stroke engines, but later switched to rotary valves in search of more peak power. By the 1980s, reed-valve technology had come a long way, so Yamaha returned to reeds, no doubt encouraged by Spencer’s 1983 title win on Honda’s reed-valve NS500.

Second, the chassis. The 0W76 featured Yamaha’s and MotoGP’s first proper twin-spar aluminium chassis, instantly recognisable as the great-granddaddy of those currently used by Aprilia’s RS-GP, Ducati’s Desmosedici, Honda’s RC213V and Yamaha’s YZR-M1.

Honda’s 1985 NSR500 copied the concept, as did Suzuki, when it unleashed the RGV500 in 1987. Within a few years every factory bike on the grid used aluminium twin-spar chassis powered by reed-valve V4s. And it stayed exactly like that until the 500s were legislated out of existence in the early years of the 21st century.

Yamaha took another step forward in 1985 when it installed contra-rotating crankshafts in its 0W81. Its earlier V4s had both cranks spinning the same way, which creates gyroscopic effect, which hurts handling and steering. Contra-rotating cranks largely cancel each other out. Cagiva and Suzuki soon followed suit.

From there to the final 2001 500cc season the YZR500 developed step by step, but never won another title after Rainey’s hat-trick, because Honda’s NSR was too good and its riders, especially Mick Doohan and Valentino Rossi, too talented.

When the big four-strokes were announced, Yamaha decided to build an inline-four 990, largely a marketing decision to promote its range of inline-four road bikes.

After all, this was the whole point of switching to a four-stroke only class. Racing two-strokes was no longer of interest to the manufacturers because they had stopped selling two-stroke road bikes, so the only way factory race departments could get decent budgets out of their big bosses was to race bikes that had some relevance to the road market.

The first iteration of the YZR-M1 was a disaster, a bit like the first V4. Yamaha’s first four-stroke GP engine was 50cc under the capacity and used carburettors, not fuel injection. Meanwhile Honda’s sublime RC211V V5 rewrote the rules of what a MotoGP bike should be. In the first two years of the 990s the RC211V won 29 GPs, against the M1’s two.

Then Rossi arrived, the Italian superstar just one part of a complete overhaul of Yamaha’s MotoGP project. Rossi rode the M1 to the 2004, 2005, 2008 and 2009 titles, Jorge Lorenzo followed with the 2010, 2012 and 2015 crowns, then a long wait before Fabio Quartararo beat Ducati’s Pecco Bagnaia to the 2021 championship.

However, the writing was already on the wall. V4 MotoGP four-strokes had always had more horsepower than the inline-fours but they struggled in the corners, until the arrival of downforce aerodynamics fixed many of those issues.

That’s why Yamaha is building a V4, because the inline-four’s corner speed advantage is no longer enough and when everyone else – Ducati, Aprilia, KTM and Honda – is racing V4s you need a V4 to battle with them.

I wonder if Yamaha will call its new bike the YZR-M2.