History of V4

The History of Honda V4

Honda started the New Racing (or NR) project 1978. They created the revolutionary NR500 machine 1979, with a totally new chassis and a V-motor with short stroke, oval pistons and magnesium carburettors. The racing public saw the first NR500 at Silverstone on August 12, 1979, but it was unpredictable and difficult to control. The race was an embarrassment and the NR project suffered from internal conflicts between engineers anxious to push back technical frontiers, and race-team management desperate to win races for which they required a reliable motorcycle with consistent behaviour.

1982 came the first road-going Honda V4 was the VF750S or Sabre in the States. The first V4 racer with conventional pistons was introduced in June, 1982, Honda RS1000RW with 150 hp driven by Freddie Spencer. This machine was to fast (top speed over 300 km/h) for diagonal tires and Honda had to develop the first Radial tire for motorcycles together with the Japanese tire manufacturer Bridgestone. 1983 launched Honda the V65 Magna, and a new model that looked set to reclaim the sporting image, which Honda was so keen to re-establish. The model was VF750F, known as the Interceptor in the USA.

This was the first modern 750 cc designed for Superbike racing. The crucial factor in the F-model being launched in 1983 was that the American Superbike Championship's capacity limit for that year dropped from 1000cc to 750cc. The motor was obviously directly related to the 750S, but everything else was new. The chassis was much more sporty, comprising rectangular-section steel tubing in a wide double-cradle layout. It was painted silver to look like aluminium, but only the swinging arm was the real thing, mainly because American Superbike rules forbade changing it. Suspension was Pro-Link at the back with air assistance and four-way rebound damping adjustment. The front forks followed the S-model's lead with the TRAC (Torque Reactive Anti-dive Control) anti-dive system on one leg only, and were also air-assisted with three-way damping adjustment. The F-model got a 16-inch front wheel carrying a wide, low-profile 120/80 tire. Visually, the VF was revolutionary. The frame was deliberately made a styling feature, it's silver tubing contrasting with and wrapped closely round the black engine.

There were two 1000cc VFs introduced in 1984: VF1000F the sport model, VF1000R the racing model with gear driven camshafts and with a full fairing. A touring oriented version VF1000FII Bol d'Or with a full fairing, an 18-inch front wheel and 44 mm longer wheelbase came in 1985. None was a commercial success, only on the racetrack did Honda enjoy the success.

VF1000F
According to a chassis dynamometer tests in 1984, the VF1000F acceleration was incredible: 0-100 km/h in 3,2 sec. , 70-110 km/h (on the second gear) 1,9 sec. (70-110 km/h on the highest gear (5) only 4,2 sec.) 0-400 meter 11,4 sec. The top speed was approx. 225 km/h. It was possible to drive 320 km without using the reserve, = 6.2 lifters/100 km. Brakes: the bike stopped after 35 meter at 100 km/h. The oil pump is 18 % more effective than VF750 and the waterpump 40 % more effective. There were only two different colours available on the Swedish market:
Black/Red/White and Black/Silver/White , but it also exists in Blue/White/Red .

Camshaft crisis

In 1984 a substantial numbers of VFs had suffered camshaft problems, and owners were besieging dealers with warranty claims and demands for reassurance. Honda did not really know what the source of the problem was, and at first they refused to acknowledge that there was a problem at all. Inadequate oiling was the first diagnosis, and the attempted cure was kink-free oil lines, less restrictive banjo bolts, putting oil pick-up holes in the base of the cam lobes and closing-off the ends of the hollow camshafts. Oil change intervals were also halved to 6.400 km (4000miles). Heat was seen as a potential cause because VF motors run hot and, despite the water cooling, the rear cylinders run hotter, as evidence by the fact that the rear camshafts were usually the first to fail. Other causes were investigated, notably the camchain tensioners, an area where Honda had a recent history of inadequate design.

At last the truth was in sight, but there was another false start before the problem was completely resolved. Honda had identified that incorrect valve-lash adjustment resulted in the camshaft surface being damage. Of course, this all involved treating the symptoms, not the root cause of the problem, which was excessive clearances in the camshaft bearings.

The only long-term cure was both radical and expensive: replacement of the existing camshafts and camshaft caps with new components, hand-matched so that they had the correct clearances. It is possible to identify at least three types of camshafts: the original, a second-generation with small oil holes in the cam lobes and the final type with both the oil holes and closed ends. Honda spent large amounts of money replacing camshafts for several years.

Heat is a big problem. Despite liquid cooling, these engines do get hot. Usually the rear cams are the first to go because they get hottest. The working temperature of the engine is 82° C (180° F) and the thermostat begins to open at 80-84° C (176-183°F). The red field on the gauge indicates a temperature over 110° C (230° F). Because the system is under pressure the boiling point (at 50:50 mixture) is 125,6° C (258° F).
To solve this problem you need a premium quality oil, preferable synthetic (Mobil1) with the pumpability of 5W-50 on start-up. Change it a lot, at least every 600 km or 6 month. A good idea is also to upgrade the thermal switch, which controls the radiator fan. Order part # 37760-KE7-003 , it's the original thermal switch mounted on VF400 and it will lower the fan threshold by 10° C (50° F). (Sabre/Magna part # 37760-mb4-770)

How to convert 50° Celsius to Fahrenheit: 50 x 1.8 + 32 = 122
Convert 100° Fahrenheit to Celsius: 100 - 32 / 1.8 = 37.8