The 6-hour special
Honda had not won Australia’s biggest and most important race, the Castrol Six Hour, since 1971, and it hurt. The original superbike, the CB750, had been outgunned by a succession of models such as the Kawasaki Z1/900, BMW R90 and R100, and the Yamaha XS1100. Just when the new Honda CB900 looked to be in with a chance, along came the Suzuki GS1000, followed soon after by the GSX1100.
If there was any question that the race was now attracting keen interest from the Japanese factories, it was answered emphatically in August 1980 with the announcement that Honda would build (and register) 100 examples of a machine dubbed the CB1100R – specifically to win the Six Hour. To the letter of the regulations, the CB1100R was supplied with a dual sat and pillion footrests – and with a bonus single seat/tail fairing. But the rest of the engineering had a single purpose in mind. While based on the standard CB900F, the CB1100R differed in almost every aspect. The red-painted frame shared no dimensions with the 900, and the forks, rear suspension units, brakes and wheels were all unique to the model. The clip-on style handlebars were almost infinitely adjustable and could also be changed quickly in the event of a prang. Stopping power was another area where the Honda scored heavily over the Suzuki. Up front were dual-piston brakes which had each pair of pistons side by side in a floating calliper
Amaroo Park placed considerable demands on ground clearance, particularly on the right hand side. To this end, both crankshaft end covers were reduced in size and chamfered, the exhaust headers tucked well in, footrests raised and mufflers kicked up out of the way. Honda claimed the bike could be banked to 50 degrees on either side before anything scraped. In the race, several were banked well beyond 90 degrees.
The engine shared the same stroke as the 900 – 69mm – but had been punched out to 70mm bore to bring the capacity to 1062cc – the same as the factory RSC Superbikes. With a compression ratio of 10:1, the motor produced 85.75 kW at 9,000 rpm, measured at the crankshaft. One of the areas that handicapped the CB900 was the 2.15 front and rear rims, severely restricting tyre choice. On the CB1100R, the rear grew to 2.75 x 18 and the front to 2.5 x 19. On paper at least, the Honda looked to have the Suzuki challenge well covered. The CB1100R weighed 14 kilos less and produced 10kW more power, with better brakes and ground clearance.
For 1980, the specially-produced Suzuki GSX1100 ‘Six Hour Special’ – 120 examples of which were imported - sported wire-spoke 18-inch wheels, as opposed to the standard version with a heavy cast-alloy 17-inch rear. At the time, there was no 17-inch rear tyre capable of containing the ever-expanding horsepower of the Japanese 1100s, hence the switch to the bigger (and lighter) rims.
When entries closed for the 1980 Castrol Six Hour Race, no fewer than eight teams had opted for the new Honda, ranged against seven wire-wheeled Suzuki GSX1100s plus one alloy-wheeled version. As well as the on-track action, pit crews were drilled and re-drilled for refuel ling and wheel changing. The Honda gained a few more seconds on its rivals with a rear wheel that was in and out in around 45 seconds.
By the time the 39-strong field lined up for the Le Mans-style start, it had been raining for more than one hour. Tyre choices were out the window. Dennis Neill abandoned his plan to start the race and handled the pole-sitting Honda to team mate Roger Heyes. From the Le Mans start, Wayne Gardner on the Mentor Motorcycles CB1100R grabbed the early lead as the field splashed around, but within a couple of laps, John Pace was through on his Suzuki. From that point on, there were effectively only two bikes in the race. Wayne kept a watching brief for half an hour, then pushed through to establish a gap that was big enough to hold the lead even through five pit stops. After two 90-minutes back-to-back stints, Gardner handed over to Andrew Johnson for another two hours, then took the seat for the remainder – or so he thought. With 45 minutes remaining, he was back in the pits to unkink a fuel breather hose, but on a drying track, he held out Neil Chivas’ final charge to rack up 322 laps before the chequered flag came out at 4pm. Four laps adrift came the Heyes/Neill CB1100R. As a measure of the conditions, it was the lowest lap tally since the very first Six Hour in 1970. Honda had won the victory they so desired, but had only two 1100s in the top ten, albeit in first and third places.
Sydney enthusiast Terry Pinson purchased the winning Honda from Mentor Motorcycles shortly after the 1980 Six Hour, ostensibly to use as road transport and ‘a bit of an investment’. The Honda thereafter enjoyed a slightly less hectic life as road transport, with the optional dual seat and passenger footrests fitted. However one fairly spirited outing ended with the Honda spinning down the road, destroying the unique black-chromed exhaust system. An O’Brien four-into-one system went on as a replacement, although the original system is still listed and supposedly available as a Honda genuine part - provided you have a spare $3,000. Otherwise the bike is still exactly as it came off the track at Amaroo: even down to faded 2MMM and Bel Ray stickers, and unrestored paintwork in the Mentor/Molloy colours. With some recent sales of the original 100 bikes fetching around $20,000, it would appear Pinson’s investment has paid off. It is currently on display at the National Motor Racing Museum, Bathurst.