PROTON KR3
The exotic Proton KR3 GP came close to perfection in 2002… before being outlawed to make way for MotoGP’s new ‘diesels’
It was murder, plain and simple. Murder by committee. The victims were some of the most beautiful racing motorcycles ever made. The V3 Protons, created by a legend and crafted by engineering artists, were cut short in their prime. Not before, however, one of the lithe, lightweight triples claimed a final pole ahead of the new MotoGP monsters at Phillip Island. Jeremy McWilliams set the fastest-ever lap at what was then the fastest track on the calendar.
That achievement was a final high point, confirming its status as the fastest two-stroke GP bike ever. A fact backed up with best two-stroke laps and race times at several other circuits in that 2002 season.
In that race, as elsewhere, McWilliams and teammate Nobu Aoki were bullied out of the way by the new-generation 990cc four-stroke MotoGP bikes. Having a faster lap time didn’t help. Clumsy through the corners but faster down the straights, ‘the diesels’ were always able to get in the way. Two-strokes were doomed, deliberately so, by rules that gave fourstrokes a double-size advantage. If only they’d had one more year, the final iteration of Kenny Roberts’ dream of challenging the Japanese factories had every chance of success.
It had begun seven years earlier, with a typically maverick decision by Roberts, the former triple champion now a team manager for Yamaha. Kenny was still a king, but something chafed. He would describe the factory Yamahas as “sticker bikes”, bemoaning how at year’s end the factory takes them back. This undervalued the role of the team’s engineers, and left the team with nothing beyond their trophies. Kenny’s move to become a racing manufacturer in his own right was typically bull-headed, but the pitfalls were not all of their own making. Backing and the name Modenas came from a Malaysian scooter brand, but the technology was British, and inspired by the light and agile threecylinder Honda on which young Freddie Spencer narrowly beat Kenny’s more powerful V4 Yamaha in 1983. Kenny knew to his cost just how effective better braking and corner speed could be.
The rules were helpful, with a minimum weight of 115kg for a triple compared with 130kg for a four. Team Roberts engineers, led by the late Warren Willing, modernised and developed the idea, but renowned race-car engineer Tom Walkinshaw, his TWR firm prominent in the F1 Belt surrounding Roberts’ Banbury base, was responsible for final design and manufacture.
Work started during 1996, and when the bike took to the tracks in 1997, it was condemned to go through early development very much in public. This proved rather embarrassing, for there were many teething troubles and breakdowns for the riders, French exoff-road superstar Jean-Michel Bayle and Kenny’s eldest son Kenny Junior. Results up against Honda, Yamaha and Suzuki were sometimes respectable: Bayle qualified on the front row at Brno, and achieved three eighth places (Junior got two). But the Mk1 Modenas had one over-riding flaw, explains Team Roberts stalwart Tom O’Kane, nowadays heading Suzuki’s test team. “It was a very clever bike,” he says. “But some ideas were ahead of their time.”
‘It was a clever bike but some ideas were ahead of their time’
‘You could literally ride it to the shops – it would tick over at the lights’
One original feature of the twodown/one-up V3 engine was that two cylinders shared a common crankcase volume, with one downcylinder piston rising and falling in synch with its adjacent up cylinder, and no main-bearing between them. “We used to call it ‘a flying web’, because the middle web was unsupported, with a crank-pin on each side of it,” O’Kane says. “It was an ambitious design, and there were certain issues with cylinder filling, with two carbs feeding into the same crankcase volume.”
Another unconventional feature was the under-seat radiator, fed by an air duct beneath the fuel tank. O’Kane continues: “That bike had standpipe carburettors, which were also custom-made.” These replace the usual float-bowl/needle valve with a weir system. “With Yamaha, we’d been having float-chamber problems with pressurising the airbox.” The special carbs were meant to obviate these difficulties. All of these were undermined by a single basic problem: vibration. “There was a decision made early on that it wouldn’t have a balance shaft, so the vibration level was quite high. We went back to conventional carburettors and radiator position, but without a balance shaft… you can’t retro-fit one.”
I summed up the problems in that year’s Motocourse: “vibration so severe that it snapped footrest hangers, frothed the fuel and the coolant, chafed through wiring, caused component failures and in general subjected the bike and its riders to a constant destruction test”. Roberts blamed a misleading promise of greater stiffness from the crankshaft manufacturer. Clearly, a redesign was required. It came with a surprising degree of help and cooperation from the Japanese rivals, largely (explains O’Kane) because of the friendship and respect for Kenny.
There were three key figures – the chief of Keihin Carburettors Mr Ito, HRC director Yoichi Oguma, and Yamaha’s “Mike” Maekawa.
The Mk2 didn’t appear until the latter half of 1998, and reversed the layout, with two cylinders up and one down. It also had a balanceshaft, and was essentially designed and built in Japan.
O’Kane explains: “The parts were made by specialised engineering firms with experience supplying the existing teams. So there was quite a crossover, and they were companies we would never have access to without Kenny being Kenny.” This help for rivals, says O’Kane, was not unusual, “for, let’s say, small operations. We’d supported the Patons back in the Yamaha days; Yamaha were likewise very generous with their resources when Cagiva were being developed. The paddock is a family, and nobody wants to see anybody humiliated. It’s a very Japanese thing.”
The second engine eliminated the vibration with a balance shaft. But this brought its own problems. “It was basically quite long – the layout of the shafts was like an older design, less ‘stacked’ than current designs. That meant we couldn’t get the chassis performance we wanted.” And how: 1999 was the worst season yet. Junior and Warren Willing had both gone to Suzuki, Bayle was hurt and retired mid-year; several riders including David de Gea, James Whitham and Mike Hale faced all sorts of problems.
But Mk2 bought the team time to design and build the ultimate KR3. Engineer John McGee was a crucial addition. He designed a compact and well-balanced bike, which rider McWilliams describes as “the most beautiful I ever rode… the bike I felt more at home on than anything else.
“The thing was like a little toy – so easy to flick, to steer. You could put it wherever you wanted, and it delivered the power so smoothly and seemed to get a lot of grip from the tyre. By the end of 2002 we were pretty much on equal footing with the V4s. Lacked a little bit of top speed, but you’d make it up on the brakes and in the corners.”
At the same time, “it was such a clean, efficient little motor, you could literally put lights on it and ride it to the shops – it would tick over at the lights.
“A 500cc two-stroke went 202mph way back in 1993. Had we continued with development, with the current injection technology, I reckon two-strokes would be going quite a bit faster than the current four-strokes – and they would be incredible to watch.”
KTM’s development of off-road two-strokes, in which McWilliams played a role, proved them cleaner than four-strokes as well. “And nothing beats the sound a twostroke,” he added.