Honda VF750 Birth of the V4
By the late ‘seventies, Honda’s venerable across-the-frame four was looking a bit tired, at least in marketing terms. Inside the world’s biggest producer of motorcycles, it was time for a change. A V change.
Leaving the Grand Prix two-strokes aside, Honda had initially embarked on a four-cylinder Vee formation four-stroke with the NR500 racer, first seen in 1980. Except that the NR500, while technically a V4 to comply with the FIM regulations that stipulated no more than four cylinders in the 500cc class, was really a V8, with eight conrods, 32 valves and oval pistons. History records that the NR500 was a humungously expensive exercise that netted just two race wins over two seasons – the first at Suzuka in Japan in early 1981 and the second, and final, at Laguna Seca, USA in July of the same year, when 19year-old Freddie Spencer won a five lap sprint race. However, without the lessons learned in the NR500 project, painful as they may have been, the future would have been very different indeed. In 1983, Honda surrendered in the 500 GP class and went with the flow, first with the lithe and user-friendly NS500 v-3 two stroke, and later with the NSR500 V-4 two stroke. But the V-4 four stroke concept was not dead, with a line of very successful V-4 endurance RVF racers emerging. The oval-piston concept, for which Honda had filed numerous patents, was even dusted off in the form of the 165hp NR750, which was given a win by Tasmanian Malcolm Campbell at the Calder Park round of the 1987 Swann Insurance International Series during the European off-season. The FIM replied to that looming threat by banning oval pistons from international racing. ‘Racing’ here is the key word, because after another hiatus, the oval-piston concept appeared again in the form of the luscious NR750 road bike (also known as the RC40) which made its public debut (as a marshals’ bike) at the 1990 Suzuka Eight Hour Race. So to hark back to road motorcycles, as opposed to racing exotica, we need to visit 1982, when Honda launched the first road-going V4s, sold as the V45 Sabre in the USA (the ‘45’ referring to the capacity in cubic inches, actually 45.69 ci or 748.8cc) and as the VF750S elsewhere. For the 1983 American market, there were also two Magna models – in semi chopper style – in 45ci and 65ci (1098cc) sizes. These shaftdrive models used a six-speed gearbox. Why a V4 anyway? Back in the ‘thirties, both Matchless and AJS had used the layout, which is narrower than a transverse or in-line four, has a ‚
shorter and hence stiffer crankshaft, and in 90degree form, a near perfect primary balance. As far back as 1919, Melburnian Saville Whiting designed and built a complete motorcycle powered by his own 500cc side-valve V4 engine (see full story in OBA 10). The new Honda engines adopted a specification of water-cooled, ninety-degrees, double overhead camshafts with four valves per cylinder, but with major differences in the cylinder head design itself. In place of its traditional 60-degree angle between inlet and exhaust valves, the new V4 used a 38 degree angle, basically taken from the NR500, with a flatter combustion chamber and piston crown. In USA, the Sabre and Magna models sold in satisfactory numbers, the larger V65 particularly, especially after Honda hired top drag racer Jay Gleason who took the machine to a 10.92 second quarter-mile time at Orange County Raceway in California – at that stage, the fastest production motorcycle ever tested. Honda made much of the achievement, and the fact that the V65 was actually built in USA at the Marysville, Ohio plant which had previously built Goldwings. The European market on the other hand was lukewarm to the V4 concept. After all, Honda already had an excellent design – and a highly successful one in TT racing – in the DOHC CB750 and CB900 models. But in 1983, along came a substantially redesigned V4, known as the V45 Interceptor in USA and the VF750F in other markets, including Australasia. The VF750F used basically the same engine, but with a five-speed gearbox. This change came about because of the choice of chain drive over the earlier shaft, meaning a smaller gearbox capacity and room for only five ratios to fit comfortably. It used a rectangular-section steel frame which was dimensionally similar to the racing RS1000RW that had enjoyed much success in AMA, Endurance, and even TT racing. The frame was painted silver and neatly matched the aluminium-alloy swinging arm. Honda also managed to reduce the price in most markets to somewhere near that of the CB models, and with 86bhp and around 210km/h available straight out of the box, the V4 was undeniably quick. The styling was all- new, with a purposeful three-way adjustable airassisted front end featuring Honda’s TRAC anti-dive, with a half fairing to contain instruments and warning lights, as well as provide a degree of wind-cheating. Honda chose a 16-inch front wheel, which was at the time the way to go in GP racing but was soon superseded by the 16.5 and later 17 inch hoops, with an 18-inch at the rear, suspended by the company’s ProLink system with four-way damping adjustment. Front forks were an interesting design with air assistance and, on the right side leg only, three-way damping adjustment. To keep everything cool, the liquid passed through twin radiators, and although this should have been entirely adequate, very soon after its release reports began filtering in of overheating issues, and worse still, premature camshaft wear. Honda had a big investment in the long-term viability of this concept, so sprang into action to mount a remedy before it became a pandemic. What transpired tarnished the model’s reputation considerably – not to mention its sales – and for a an explanation we turn to the words of author and model expert Greg Pullen in his 2014 book, Honda V4. The Complete Four Stroke Story. “Although the theories and fixes came thick and fast, starting with revised jetting and then various camshafts and tools for tappet adjustment, the reliability and quality-control problems of the 1982 VF model were eventually attributed to the automated production equipment…Revisions were brought in in 1983 to address the problems from the previous production year…but they proved inadequate. More camshaft woes surfaced during 1984, with half a dozen cam revisions over the course of a single year. With the early V4s, the problem with camshaft wear – in an ironic twist – was blamed on the decision to use ‘less troublesome’ threaded tappet adjustment rather than shims...In essence, the problem was that the camshafts could rock in their bearings if the tappet adjustment was incorrect, or if the top and bottom castings that had the camshaft bearings machined into them were not a good match. Honda did not match components to get the best fit from the inevitable variations in mass production, instead trusting to the precision of their new machinery to avoid such variations. In addition, rough castings could lead a mechanic to ‘feel’ he had the tappet correctly adjusted and secured by a locknut, when in fact further tightening was needed.
“As a result, camshafts and cylinder heads continued to wear catastrophically…At first, Honda believed the solution lay in improved oilways, and they pressed ahead with V4 road bikes in an ever higher state of tune, with disastrous results. These problems were most obvious and embarrassing on the VF750F (Interceptor). Perhaps this was inevitable given that this was the V4 in the highest state of tune (90hp at 10,000 rpm was phenomenal for a four-stroke 750 roadster in 1983), and because the model was most likely to be bought by a demanding rider. Because the V4’s woes stemmed from unmatched components, some engines were affected more than others, and some not at all; it all depended on how poorly the components matched one another when they came together on the production line.”
A Colonial crisis
In Australia, and in New Zealand, the Castrol Six Hour Race was the ultimate showroom shootout; strictly supervised stock-standard models going head-to-head in a contest of speed, reliability, and increasingly, tyres. Based at Sydney’s Amaroo Park since 1970, Honda had won the race only three times; with Bryan Hindle and Clive Knight in 1972 on a CB750, in 1980 when Wayne Gardner and Andrew Johnson triumphed on the race-replica CB1100RB, and in 1982 with Gardner and Wayne Clarke on a CB1100RC. The organisers, Willoughby District MCC, were getting peeved over the hijacking of their race ‘for standard touring motorcycles’ by the new breed of thinly-disguised racing machines, and for 1983 introduced new regulations that reduced the top limit to 1000cc and rendered the 1100 Hondas and Suzuki Katanas obsolete. Suzuki responded with a 1000cc version of the Katana for the Outright (751cc to 1000cc) class, but the majority of the entries for the October 1983 race were for the Up to 750cc class, and overwhelmingly by Honda VF750 runners, 14 in fact. Many felt the 750s were the choice for Outright honours, and qualifying showed this, with VF750s taking the first three spots on the grid and seven of the first eight. Malcolm Campbell’s pole position lap of 55.72 seconds was a full two seconds faster than a 750 had ever managed before, and marginally faster than the 1100s had done in the 1982 race. Just 0.21 seconds covered the first five qualifiers!
There was however, the bugbear of reliability, given the VF750s’ appetite for top end components. In practice, Bernie Summers’ VF750 broke a conrod and dumped him heavily. Prior to the start, the Campbell/Cox Honda was fitted with a 140/80-18 rear tyre, a slightly higher profile than the standard 140/70. This gave a fraction more ground clearance and higher overall gearing, keeping the revs down and allowing what proved to be vital extra minutes between fuel stops. In the race, Campbell and corider Rod Cox hardly put a foot wrong in a nail-biting contest that saw the first four placegetters (three of them VF750s) finish on 372 laps – five laps more than were achieved in 1982. As it transpired, the lap and race records would stand for all time, for this was the final Six Hour at Amaroo before the race moved to Oran Park for 1984. The result also proved at least one thing; that when the engine components were properly matched and meticulously assembled (as they should have been from the factory), the VF750 was reliable as well as sensationally fast.
A one-owner example
Ken Wilson has owned the featured VF750FD since new in June 1983. To say that Ken has been a lifelong keen motorcyclist would be an understatement. During the ‘sixties his mode of transport was a 500cc Velocette Venom and it did daily duties as his ride-towork machine, and on weekends would frequently undertake lengthy trips. When Oran Park opened in western Sydney, Ken was a regular spectator, riding the Velo from his home in Melbourne. The return trip would involve leaving the circuit by mid afternoon and riding all night (often in rain) to reach work by opening time on Monday morning. No motorways
in those days, just the old, rough, single lane Hume Highway. As circumstances permitted, the Velo gave way to a series of other bikes, and finally the VF750. This was purchased from Ken’s employer, Freedom Wheels Honda at Ringwood, Victoria, owned by Frank Hodder and where leading racer Alan Decker was manager, with Ken in charge of spare parts. As previously noted, there were good and not-sogood examples of this model to leave the Honda factory, and Ken’s unfortunately fell into the latter category. Overheating was a problem that reared its head early in the piece, to the point that Ken fitted an auxiliary switch to over-ride the automatic cut-in for the radiator fans. In traffic or on hot days, he would simply switch on the fans before things got to hot to handle. Still, that was a Band Aid solution for a much more serious problem, involving a series of warranty repairs. The first fault to be corrected was the factory-replacement large capacity oil line feeding the vital fluid to the cylinder head, but by the time 10,ooo km had been clocked up, the internal components were in bad order, as Ken explains. “There was virtually no hardening on the cams, nor on the followers, they just turned blue and wore out. Honda replaced these items, as well as the primary gears, which came from the new VF1000 model released in 1984. The clip-on handlebars were also replaced as these were prone to breaking, as Andrew Johnson, who rode for Freedom wheels, discovered. I had been running on 98 octane fuel but it caused all sorts of problems. Mick Smith, race mechanic for Jeffrey Sayle and others, told me that the engine would not get hot enough to burn off the additives in the high octane fuel, so I should use 91 and see if the motor pinged. It did, so I went to BP 95 and it was OK from then.” “I had to replace the rear hub cush-drive and at about 40,000km the rear shock went. I managed to find a genuine replacement in Queensland but that only lasted 18 months before it went too, so I got in touch with Darryl Groat and he supplied a Hagon shock which is still in the bike. The original black mufflers rusted out too, along with the collector box, despite the fact that I did no short trips and always warmed the bike up properly to get rid of condensation. Stuart Strickland from Honda managed to find one original black pipe but not the other so I went to Mark Harris who made Madaz stainless steel pipes at his factory. No more problems and no collector box either. But the big issue was when I got a crook batch of fuel which basically wrecked the engine. It cost $3,000 to rebuild and I didn’t have that so I got John Buskis at A1 Motorcycles to do the work and I paid it off in instalments. After that, the bike ran perfectly right until I took it off the road five years ago due to personal health issues.” Declining health has recently forced Ken to part with the Honda, and I was fortunate to be able to take it for a spin, never having ridden one before. Although it had been laid up for a number of years, once a new battery was fitted and with a fresh tank of fuel, it fired up instantly and settled into a steady tick-over. Although the tyres had some age on them, they were otherwise in very good condition. Although it is now 35 years old, everything on this motorcycle works perfectly; testament to Ken’s meticulous maintenance.
In the saddle
There are a lot of nice details about the VF750, even the fuel tap which is not the usual fiddly lever but a very purposeful looking unit set into the left side of the fuel tank. The red-faced instruments are all there in the panel set into the fairing – fuel capacity, speedo, tacho, and most important of all – engine temperature. There’s also a whole row of those coloured lights so beloved by all the Japanese manufacturers of the time, showing turn signals, high beam, and warning lights for oil pressure and tail light operation. The mirrors are set high, so you can actually use them. Ken’s bike still has the removable seat cowl that converts it from (or to) a dual seater, as it had to be for the Castrol Six Hour Race, and this is a part that is in scarce supply and prized by collectors.
For a sports machine, the VF750 is a fairly unique proposition in terms of riding position. The seat is very comfortable, the footrests slightly set to the rear, and the handlebars at a height that doesn’t tax your wrists too greatly, although it is certainly a forward leaning attitude. The quicker you ride this bike, the better it feels, because at around-town speeds it comes across as a bit wayward in the front end, a trait I am sure that has a lot to do with the fat 16 inch front tyre. Turn up the wick though, and off it goes, making a glorious rasping exhaust note on the way. Ken told me that he thought the gearbox was a bit dodgy changing back down, but I experienced none of this, in fact I couldn’t fault the operation of the gearbox in either direction, other than you seem to grab top gear a lot earlier than you may think. Part of this is because although the engine loves to rev, it also pulls like a train from 2,500 in top gear, with bags of mid-range torque, and no flat spots. It’s a gem. I found the front brakes a bit spongy, but they certainly did their job, and I think a simple fluid change and bleed would restore them to full health. Remember too, that the VF750, while a sporty steed, is no featherweight, so there is a bit of beef to haul down. I had no opportunity to fiddle with the air-adjustable front forks, and I reckon the period spent laid up in the garage has also dulled the edge here, but that’s an easy fix. The rear end, on the other hand, felt excellent.
As I said, where the VF750 hits its straps is through quick corners and on the gas. The chassis is rock steady even with the old tyres, and the bike can be flicked from side to side without even thinking about it. I can see now why it was such a weapon around Amaroo Park, and coincidentally I passed the former entrance gates to that circuit on my test ride. Sadly, the track is long gone – the scene of perhaps the VF750’s finest hour, or six.