HONDA’S V4 EVOLUTION | Columns
Honda’s RC213V is another step in a development process that started in the 70s – we look back at 10 of Honda’s big-bore breakthroughs
Honda has long believed the V4 to be the ultimate engine layout for a motorcycle, and it may be right. Done well, a good V4 mixes four-cylinder power with V-twin midrange and torque. That combination of devastating speed and easygoing power has made Honda’s four-stroke V4s dominant in all kinds of racing, including the Isle of Man TT, the Bol d’Or 24-hour and Daytona 200, as well as the World Superbike Championship and MotoGP.
Honda’s first V4 began life at a set of traffic lights near the Asaka R&D centre. Engineer Shoichiro Irimajiri was on his way home from another gruelling day spent dreaming up ways of beating the two-strokes when he had his Eureka moment. Gazing at an oval(ish) traffic-light housing, he realised similar-shaped pistons might allow him to increase valve area and give a combustion area equivalent to two normal pistons.
The result was the madly exotic oval-piston New Racer. Honda thought they might achieve the impossible and beat the two-strokes if the NR could rev twice as high. At 22,000rpm it failed, but along the way, Honda learned a hell of a lot about exotic materials, special oils, slipper clutches and so on. They also worked hard: an NR500 engine with its 32 valves and eight conrods took 60 hours to build!
Despite the NR’s failure, Honda had faith in the V4. The VF750S (the Americans called it the Sabre) was revolutionary – it was the first water-cooled 16-valve 90° V4. The VF featured cylinders cast into the upper crankcases, a hydraulic clutch and a cylinder head with details taken from the NR. Despite water cooling, the VF weighed 30kg less than the air-cooled CB900 it replaced.
The VF was praised for its smoothness and friendly power, but shaft drive and mid-Atlantic styling didn’t go down well with riders expecting something sporty. On top of that, early models were beset by engine problems which almost led to Honda axing its entire V4 program.
Although the VF750S was a cruiser with no sporting aspirations, Honda was itching to show what a V4 could do on the racetrack to help wipe away memories of the NR’s demise. The RS1000RW was packed with NR tech, like its slipper clutch to reduce wheel hop – the first of its kind in a big-bore racer bike. The engine vindicated Honda’s belief in the V4, producing over 112kW (150hp) and excellent torque. In fact, it made too much power for 80s tyre tech – Freddie Spencer led the 1982 Daytona 200 until his rear tyre flew apart. The RS was also big and heavy. Its size and its water cooling – at a time when other four-strokes were air-cooled – earned it the nickname, the Water Whale.
It didn’t take Honda long to improve on the VF750S. The VF750F (Interceptor in the US) was its first V4 sportsbike and scored the V4’s first major successes. When Spencer got a VF at Daytona in 1983, he took just five laps to beat his lap record on a 1024cc in-line four. Spencer says the bike represented the biggest development jump he experienced in a superbike career that spanned the 70s, 80s and 90s.
Spencer loved the F because it felt more like a racebike than a roadbike. He also liked its narrowness, which increased cornering clearance. The in-line four had long ago run out of clearance, so Honda removed the alternator from the crankshaft and mounted a belt-driven snowmobile ignition box behind the cylinders.
The 750F inherited its slipper clutch (a roadbike first) and Pro-Link rear suspension from the NR, while the rest of the chassis owed much to lessons learned from the Water Whale.
Superbike racing was already huge in the US, but it had yet to cross the Atlantic. So while Spencer and Fred Merkel dominated with the Interceptor, Honda built something different for Europe.
The RS860 – an over-bored VF750 motor in an F1 race chassis – was immediately just as dominant. Honda France won the Bol d’Or 24 hours, Wayne Gardner won the 1983 British F1 title on his 860, and Joey Dunlop won the F1 TT and F1 World Championship. This was the start of Honda’s V4 dominance that continued into the 90s.
The 100kW/275km/h (135hp/170mph) RS was fast and bulletproof, partly due to the V4’s shorter, stiffer crankshaft which also required fewer bearings for reduced internal friction – always a Honda obsession.
The RVF750 was the bike that fully established Honda’s V4 legend. For more than half a decade it was the most successful four-stroke on the planet. In 1985, when Spencer won the first-ever Daytona 200 superbike race on the VF, the RVF won the F1 TT, the Bol d’Or and the Suzuka 8 Hour.
While the RVF’s engine was similar to the RS860’s, the chassis was all new. The twin-spar aluminium frame was based on Honda’s NSR500 and NSR250 GP bikes, while its single-sided swingarm came from the innovative Elf endurance racer.
Although the VF750F dominated the US scene in ’84 and ’85, Suzuki’s GSX-R750 also arrived in ’85, so Honda had to get busy. The VR750 turned up one year later and swept all before it, adding to the V4 legend. The VFR was also the bike that turned the masses onto Honda’s V4. On the road and the track, it was a superb all-rounder: fast, agile and easy to live with.
Once again, lessons learned in HRC’s V4 racing program featured heavily. The VFR inherited gear-driven cams from the RVF, reducing friction by 30 per cent. The twin-beam frame was also inspired by the RVF and allowed Fred Merkel to ride so hard that he bent the front forks. Honda subsequently equipped the bike with a GP front end.
The RC30 was Honda’s greatest V4 for the common man; well, the common man who had around $20,000 to blow. The RC was a World Superbike homologation special which sped sportsbike development forward by at least five years. The engine was much changed – its 360° firing order created that wonderful droning exhaust note, which evokes memories of the TT and the Bol. It had titanium rods, which weighed 50g less than the VFR’s, and cost eight times as much. The twin-beam chassis shared the same geometry as the RFV, allowing riders to ride impossibly tight cornering lines, just like Mick Doohan and Wayne Gardner on the RVF.
The RC won the first two WSB titles and dominated the Isle of Man for years, winning its last TT in 1993, five years after its launch.
The RC45 was the successor to the RC30, but did little to further the V4 legend. Honda started all over again – so much so that the RC45 project leader never even spoke to the RC30 boss!
Everything was new. Bore and stroke were changed for the first time since the VF750S, from 70 x 48.6mm to 72 x 46mm, for more revs. The chassis was all new and the bike weighed more than the RC30.
While the RC30 won WSB first time out, the RC45 took four years, by which time HRC was spending more money on the bike than it had on the NSR500. The 45’s strong point was endurance – it won five Suzuka 8 Hours.
And here it is, the bike that’s the blueprint for Honda’s latest racer on the road, just as the RVF750 was the blueprint for the RC30. The RC213V was Honda’s first V4 four-stroke MotoGP machine, arriving three decades after the VF750. Of course, it’s entirely different from its ancestor, but at its heart it’s still a water-cooled, 16-valve, 90° V4. It does produce a bit more power, however, up from 60kW to 186kW.
Words Mat Oxley
Pics AMCN archives