1970: THE 'CB750/CR750' REVOLUTION: Following the introduction of the production CB750 at the Tokyo Motor Show in 1968 Honda decided to 'race' a slightly improved version, this following advice from United States Honda Dealers that if Honda didn't go racing with the 750/4 others would, possibly less successfully.
In 1970 Honda decided to enter the premier USA motorcycle race, the Daytona 200 at Daytona Beach, Florida. No doubt to show the motorcycling public that a race prepared CB750 code named 'CB750 Racing Type' could win the prestigious event. Tommy Robb, Ralph Bryans and Bill Smith were initially appointed to ride three of the four Honda's entered, incredibly Dick Mann, deemed 'too old' by Triumph, was offered the fourth 'winning' machine by Honda's Bob Hansen. All but Mann's Honda had reported cam chain failure during the race, Dick Mann nursed his CB750 home in front of Gene Romero's Triumph Trident 750 triple.
In my opinion Honda's success at the Daytona 200 Miler was the most significant individual win in their history as regards potential sales of production motorcycles. The win paved the way for massive sales of the CB750 at the expense of Triumph T150's and BSA Rocket III's. Production, improved production and clones of the 'CB750 Racing Type' soon took to the race track, ultimately the 'CB750 Racing Type' became known as the CR750.
In Australia a CB750 in the hands of Craig Brown nearly won the 1970 Castrol Six Hour Production Race, finishing second. In 1971 a CB750 in the hands of Bryan Hindle and Clive Knight won the event for Honda.
1979: THE 'NR500(OX)' MONOCOQUE: Audacity run wild here, Honda re-entered the 500cc World Motorcycle Championships in 1979 with a four stroke, when the opposition two stroke race machinery was totally dominating the race track. Honda needed more revs, more swept volume and significantly better breathing (valve technology). Simple really, build a V8 when the 500cc class regulations only allowed four cylinders. To get around the four cylinder ruling Honda developed a V4, made from magnesium and titanium, with OVAL PISTONS incorporating an eight valve head arrangement. More audacious features included a monocoque 'chassis' and the motorcycle wheels were small, nominally 400mm diameter, there were also some very unusual issues at the front of the motorcycle including exposed suspension springs forward of the fork sliders and the disc brake calipers were mounted forward of the entire suspension system. More audacity, no problem, side mounted radiators held to the monocoque by rubber straps and the radiators were totally exposed to damage, however they were not exposed to face the main air stream!
The 'NR' prefix meant 'New Racing' to Honda, with the amount of set backs and unreliability the Motorcycle press of the day considered it really meant 'Never Ready'. Ignoring the bad press, Honda entered the British Grand Prix of 1979, riders Mick Grant and Takazumi Katayama attempt to qualify, enter the grid on race day and actually race the NR500(OX), suffice to say the entries were a disaster for Honda. Mick Grant crashed on the first corner due to an engine oil leak contaminating the rear tyre and Takazumi Katayama's motorcycle suffered electrical problems, retiring before mid race.
The NR500(OX) monocoque disappeared quickly from the scene, however the engine technology appeared again in 1981, housed in a more conventional double loop motorcycle frame, suspension and brakes.
The NR500(OX) engine specification: Liquid cooled, 499.5cc, 100 deg V4, OVAL PISTONS with DUAL connecting rods, DOHC 8 valve head, cams gear driven, producing over 115PS at 19,000rpm. The gearbox incorporated a six speed transmission.
1981: THE 'RS1000' ENDURANCE RACER: Developed from the CB750 and 900F, this motorcycle in the hands of Americans Dave Aldana and Mike Baldwin won the Suzuka Eight Hour which formed part of the 1981 World Endurance Championship.
The RS1000 engine was a 999cc four cylinder DOHC with a four valve head arrangement, producing 130PS at 9,500rpm with a five speed transmission.
1981: THE 'NR500' - OVAL PISTON 2X: This motorcycle was developed following the disastrous attempt by Honda to race the NR500(OX), basically the NR500 engine was now placed in a conventional looking racing motorcycle double loop frame, suspension and brakes.
The '2X' had limited success in 1981, Freddie Spencer's race win at Laguna Seca and Kengo Kiyama's win at a 200km race in Suzuka were the highlights. Ultimately the entire exercise was a disaster for Honda on the race track, although the technology could never be questioned. The engineering ultimately appeared on the most gorgeous Honda road motorcycle ever made, the NR750 OVAL PISTON.
The 1981 NR500(2X) engine specification: Liquid cooled, 499.49cc, 90 deg. V4 (changed from the 100 deg. V4 of 1979), OVAL PISTONS with DUAL connecting rods, DOHC 8 valve head, cams gear driven, producing over 120PS.
1982: THE 'CB750F' RACER: This motorcycle was developed wholly within the USA by American Honda for the Daytona 100 Miler. The motorcycle was built around a Honda RSC based RS1000 engine and in the hands of American Freddie Spencer it won the 1982 event with similar machines piloted by Americans Mike Baldwin and Robert Pietri taking the minor placings.
The CB750F Racer engine was a 1,023cc!! four cylinder DOHC with a four valve head arrangement, producing 140PS at 10,500rpm with a five speed transmission.
1983: THE 'NR500' - OVAL PISTON: An even more audacious twist to the 'Oval Piston Racer' appeared in 1983, this time the engine was suspended from a frame, suspension, swing arm, fork tubes and wheels, which were all 'carbon fibre'. Comparing the '1981 NR500' images above, to the 1983 machine it is clear that an oil cooler was added to supplement the liquid cooling system.
The 1983 NR500 engine specification: Liquid cooled, 499.49cc, 90 deg. V4 OVAL PISTONS with DUAL connecting rods, DOHC 8 valve head, cams gear driven, producing 128PS at 19,000rpm.
HONDA'S MASTERPIECE 'EIGHT VALVE':
HONDA'S 'TWO STROKE' SHOCK: Eight valve heads and oval pistons didn't achieve a 500cc World Motorcycle Championship for Honda, the unthinkable came next!
In 1982 Honda started a racing and development program with 'two stroke' Grand Prix machinery, for more Honda racing activities please select from the following pages:
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