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Ikuzawa Honda VFR750 Road Test

Sept 1987

I ought to own up here and now and admit I have a thing about V4 Hondas. I like them. Especially in racing form. I've never come across one that I didn't have to be prised off, and even Honda's rivals would admit that in factory spec, at least, they have a pretty impressive record over the past four or five seasons. Let's face it: GSX-R Suzukis notwithstanding, the V4 Honda is currently the world's top four-stroke racing engine.

In view of this, I find it remarkable that so few European endurance and TT F1 teams run V4 Honda-based machinery, especially since HRC offer a selection of admittedly very expensive engine and chassis kits to convert your standard road bike into — well, if not quite a Joey Dunlop replica, at least a pretty close imitation. Ask anyone who runs one of these bikes and they'll tell you that if you can afford the steep initial cost, you'll end up with an engine that is pretty well bullet-proof, yet delivers competitive horsepower whether you opt for the 360-degree VF unit or the current 180-degree VFR.

Writing this the week after watching the Barcelona 24 Horas at Montjuic, I've just had excellent confirmation of this claim. Two VFR Hondas with race-kitted engines started the race, both finished. One was second, the other fourth after losing laps early on with an electrical fault, but both were running as strongly at the end as at the start. The runner-up Swiss team did nothing but refuel and change tyres and brake pads all race.

By contrast, only two of the nine GSX-R750 Suzukis that seem to have become the de rigueur choice for the racing privateer, finished the gruelling race. Four of the seven others retired with blown gearboxes, and another with the usual Suzuki hole in the crankcases where a rod had let go. The results of that race just about sum it all up — yet in Europe for some strange reason the Honda just hasn't caught on.

Maybe things will be different next season. After riding the Harris-framed Team Ikuzawa VFR750 endurance bike, fitted with full HRC race-kitted engine, at Japan's Sugo Raceway recently, I'm more than ever convinced of the engine's merits. And when you match it to a fine-handling European race chassis, the result is a rocketship that has me groping for superlatives.

The idea for the Harris VFR came as the result of the collaboration struck up over the past year between the Harris brothers (bespoke chassis manufacturers to the world), and Tetsu Ikuzawa to manufacture the XBR Honda single-cylinder cafe racers now selling in steady numbers all over the world.

Ikuzawa, best known as the first Japanese car racer to make it into The European big-time as a member of the Frank Williams team in the 1960s and now boss of a topline endurance car team, has close links with Honda which date back to his days as a member of the works motorcycle team in Japanese national races circa 1960. Since giving up car racing, he's returned to bikes as a hobby, but like most successful men, he takes his hobbies very seriously. Apart from riding with great verve and much success in classic races, Tetsu has opened a superbly appointed retail bike shop in downtown Tokyo which concentrates on Hondas (and Triumphs!), and in each of the last few Suzuka eight-hour races has entered a Team Ikuzawa bike specially built for the event, powered by Honda engines and generally ridden by European riders.

For the 1986 Suzuka eight-hours, Tetsu decided, in view of his link with Harris, to have them design and build a machine for him to enter — or rather, not one but two identical bikes, one to act as a spare. With the recently launched race kits for the new 180-degree crank VFR750 now available from HRC, the choice of power unit was obvious — though with engines and spares supplied directly from HRC, this was perhaps more of a semi-works entry than a true privateer effort!

Whatever, in this way the first-ever V4 Harris-Hondas came to be built; though as Steve Harris recounts, it was a close-run thing to have them ready for Suzuka.

"Tetsu first placed the order in February this year," he explains, "but the set of HRC crankcases sent over in April turned out to have different engine mounts from the standard cases, so though we drew up the chassis and built some of it, when the race engine arrived in mid June we had to do a lot of work over again. With the race at Suzuka at the end of July, we had only time for a brief test at Mallory which didn't teach us much, before shipping the bikes out to Japan a couple of weeks before the race. We ended up having to do most of the development out there, but the Team Ikuzawa set-up is so professional and well-equipped we were able to sort out most of the problems in time for the race."

The eight-hour big name occasion that the Suzuka endurance round has become, almost ended better than the team could have dared hope: with an hour to go, riders Graeme McGregor and Ray Swann were lying eighth overall and first privateer Honda. Sadly, the final pit stop saw the rear brake caliper jam when the pads were changed as a precautionary measure, dropping the bike to a disappointing but meritorious 12th place at the finish. Six weeks later, it was presented in its eye-catching all-white livery for me to sample at Sugo: a rare and sweet treat lay in store.

Like other recent Harris racing chassis for the Rotax 250 and Yamaha FZ750 engines, the British-built frame for the VFR unit is a Cobas/Deltabox-type twin-spar design, manufactured in high-grade aluminium, now specially made in the UK to Harris's specification: previous supplies used to come from France.

"Really, it's the obvious design for this engine," says Steve Harris. "The V4 Honda is a very unusual shape for a motorcycle engine — almost square. With all the different mounting points down at the back of the cases, it lends itself very well to this type of chassis, though you do run into problems with the swingarm because of the run of the rear exhaust pipes. That's why we had to run a split swingarm."

The actual chassis itself weighs just 8kg, though thanks to the considerable weight of the engine itself, the bike as a whole is no lightweight, scaling 375lb dry in endurance form with lights and starter. However, it's so beautifully balanced that apart from a subconscious feeling of bulk, you aren't aware when you ride it, that it's such a big or heavy motorcycle. Nor does it feel like it has an extreme forward weight bias as is the current fashion — yet it has, at 54/46 per cent (front/rear), a fact you would never guess from the ultra-cosy riding position, close-coupled, compact, yet without throwing undue weight on to the rider's arms and shoulders which would quickly become tiring in a long distance race.

I must admit that I've had occasion to be very critical of the steering of Harris race frames in the past, particularly their second attempt at the 750/600 Ducati engine which seemed to me to have far too much trail and an abrupt transition from understeerto oversteer which required a high degree of commitment and great concentration to ride hard. The VFR Ikuzawa Honda couldn't be more different.

Harris appear to have completely re-thought their approach to front end geometry, making for a more controllable, less nervous bike that is reassuring to ride, yet steers quickly and easily into the turn. Trail is a more conservative 4.1 in and the head angle is a nominal 24.5-degrees, though this can be altered in half degree increments from 24- to 26-degrees with cups and cones.

It was the biggest bike by far of the several I rode that day, yet I doubt if any were as quick through the tight bottom chicane as the Harris-Honda. It could be flicked from side to side almost effortlessly, with the beautifully progressive rear suspension rising and falling gently as the White Power unit compressed and released over the bumps and dips. It felt like floating on a cushion of air: is this the first racing hovercraft?

At the front, the choice of White Power's new generation inverted forks doubtless had much to do with the bike's excellent response under braking — you can stand on the front stoppers well inside the 150m board from top speed in sixth gear, yet know that you'll brake without fuss down to around 70mph in third without fear of the front wheel tucking in or starting to chatter on the excellent Dunlop front crossply, then boot it hard through the second part, using the Honda engine's notable torque and flexibility to get a good drive out and up to the right hander soon after.

This bike is so much fun and so reassuring to ride, you can hardly stop chuckling to yourself as you scoot it round the track. About the only criticism I have of the Harris frame's handling is a lack of traction which showed up exiting the fast, off-camber, right-hand sweeper going down the hill, then again pulling hard round the right climbing up and out of the bottom chicane. Each lap the rear wheel would slide lazily but noticeably out of line, and on one occasion the rear radial which otherwise kept the situation under control let go with a full-blooded slide under acceleration. I suspect the culprit is the extreme forward weight bias, which leaves the back end light under certain circumstances, though at the same time it does indeed help to glue the front tyre to the ground on the way into corners. I suspect too this is a trait of the bike you can't dial out, but instead have to live with and be watchful for.

This was the first time I had ridden a racing version of the 180-degree Honda V4 engine —the '86 factory VFR engines have 360-degree cranks slipped inside, allegedly to give better traction due to the altered phasing of the power delivery. Gosh —what have I said: perhaps that's the reason for the bike's apparent rear end lightness. At any rate, having been delighted by my fortnight aboard a VFR road bike during the IOM TT this summer, I was surprised to find that the race-kitted engine in the Ikuzawa bike is not at all as smooth as the factory 360-degree engines I've been fortunate to ride previously. It's much cammier, and likes to be kept revving above 8500rpm to give noticeably good power, though at the same time maximum torque available falls off quite steeply after 11,000rpm. Peak power of 131bhp (presumably at the crank) is delivered at 12,200rpm according to the factory chart for the race kit, though you can rev it safely till 13,000rpm if you must.

The ultra-flat torque curve and gobs of liquid power of the factory RVF racers aren't in evidence on the kitted engine, and I suspect it would be a fair bit slower than one of then1 coming out of a slow corner like the bottom chicane at Sugo. But performance is still excellent for a kitted street engine, though with the kit comprising new pistons, rods, cams, valves, cylinder heads, electronic ignition, a beautiful multi-part, four-into-two-into-one exhaust and close-ratio gearbox, what you have here for your millions of yen is effectively a factory-built

Stage 3 power unit. Of course, they keep Stage 4 (and upwards!) for themselves ... The price of the entire kit, which also includes wheels and front forks, is a staggering £9000-odd. No wonder there aren't many of them about.

With the smooth-shifting, left foot, one-up gearchange offering a ratio for every occasion, there seemed little point revving the engine unduly, and I found it best to change up at just over 12,000rpm, which still kept the revcounter well in the powerband. By holding on to gears and making best use of the engine's still excellent torque, I found I could do the whole two-mile Sugo circuit in just 13 gearchanges, whereas with a GSX-R Suzuki I'd have needed at least another six changes more.

The close ratio gearbox was more necessary on this bike than on the 360-degree RVF, because it just isn't so lazy, but it still has a much wider band than any of the four-cylinder opposition.

The Harris chassis does retain the tendency to sit up in corners under braking, though not as noticeably as on other bikes built by them, perhaps due to the lack of an antidive system in the WP forks. These were extremely well set up, and, for example where other bikes would suffer from more or less severe front wheel chatter over the ripples round the fast left sweeper at the bottom of the hill, the White Powers just rode smoothly over them with hardly a trace of the skitters.

The Harris-lkuzawa Honda VFR is another ideal marriage, much like their XBR single-cylinder bike, of British chassis knowledge and Japanese engine development. And it's all clothed in what I find very alluring bodywork which contrives to look functionally beautiful — not quite a British Bimota, but nearly. Even the need to cut into the fairing to create space for a second water radiator to counter the cooling problems all teams suffered from at Suzuka hasn't spoiled the bike.

Steve Harris is convinced a market exists for a street version and I agree with him, especially if the option of fitting either a new(ish) 180-crank VFR or a cheaper/older VF750 engine can be offered. Ever ready to supplement the range of low-volume, high-profile bikes he offers for sale through the Team Ikuzawa shop in Tokyo, Tetsu is likely to agree with him. So it's a question of when, rather than if, we'll see a V4 Harris-Honda available for road use alongside the XBR single.

Specification

  • DOHC V4 water-cooled, four-stroke with ISO-degree crank
  • 70 x 48.6mm
  • 748cc
  • 131 bhpat 12,200rpm
  • 11.5:1
  • 4 x 34mm Keihin
  • Transistorised electronic
  • All-metal, oil-bath multiplate
  • Six-speed close-ratio
  • Aluminium twin-spar
  • Front: 54mm White Power inverted
  • telescopic forks with 40mm
  • stanchions
  • Rear: Aluminium swingarm with full rising rate monoshock suspension using White Power unit
  • 24.5 degrees
  • 4. Tin
  • 55.9in
  • 54/46% front/rear
  • Front: 2 x 310mm floating disc with four-piston AP/Lockheed calipers Rear: 1 x 220mm fixed disc with twin-piston caliper
  • Front: 5.25 x 17 Dunlop crossplyon 3.Sin. Dymag
  • Rear: 3.70 x 7.20 Dunlop radial on 5.5in. Dymag
  • 375lb dry with endurance equipment
  • 170mph
  • 1986
  • Team Ikuzawa, Tokyo, Japan.