Carole Nash
Content Writer
Published: 24th June 2008

The Suzuki road racing machines of the 1970s did battle with Yamaha, and to a lesser extent, Kawasaki, for two stroke dominance in GP500 and F750 racing.

All three manufacturers took road racing to a new level, as the phenomenal power of their bikes tested the chassis and tyre technology of the era to the limit. Riders like Barry Sheene, Randy Mamola, Graeme Crosby and many more, enjoyed great success on Suzuki machines.

Chris Pearson looks back at the stuff of legends, whilst Alastair Walker recalls seeing Sheene, Mamola and Crosby take them onto the track at the Assen Centennial in 1998.

These machines are probably the most instantly recogniz ble motorcycles in the UK, to any biker aged 35 or over. Barry Sheene, who won two 500cc GP titles on the RG500 and the 1973 F750 title on the TR750 triple, was the most famous racer of his generation and can still draw a big crowd whenever he makes an appearance at race meetings.

Chronologically, the first of the two machines is the red /white TR750. First seen in 1972, the TR750 (also known as the XR11) rocked the racing world when, piloted by Art Baumann, it qualified at Daytona with an average speed of 171mph. This was a time when a big 750 Norton, Triumph, or Ducati four stroke racer would struggle to crack 140mph on the straights.

With its power plant based heavily upon the road going GT750 ’kettle’ the TR was a quantum leap in two stroke performance – even if it didn´t win the Daytona 200 back in `72 – and went on to dominate the newly created Formula 750 class until the arrival of the all singing and dancing 140+bhp Yamaha TZ750 two years later.

Even with it´s three-cylinder engine pumping out an impressive 120+bhp the road going heritage of its design held back development against the pure race thinking of the TZ and also the final incarnations of the Kawasaki KR750 triple machines. The Suzuki was big and heavy with a large single crankshaft and five-speed gearbox inherited from it´s touring based brethren.

The piston port engine was not as flexible to ride as the big reed valve TZ750 and the casting of the Suzuki´s barrel prevented the transfer port design from ever reaching its optimum, effectively capping the power output to the 120bhp mark. The fact that the TR scored so highly on the international scene for so long was no doubt due to the array of rider talent that the works Suzuki teams, both in the UK and stateside could muster. Barry Sheene, Pat Hennen, Jack Findlay, and the late John Newbold being amongst the great names to ride the triple to top results.

With the lack of anything else to race with, the TR continued to be campaigned by the official Suzuki teams until mid 1977 when the various developments of the 500 four machine, also featured here, far surpassed the performance of the aging triple design. Even so the TR still confounded the odd critic with sterling performances right to the end of its career. John Newbold was the last man to put a TR750 on the podium at international level on July 10th 1977. John had started the season running the ubiquitous Yamaha TZ750 but a shortage of spares left him high and dry without a bike for the F750 World Championship round at Brands Hatch. Heron Suzuki stepped in and loaned him one of the very last factory TR750s for the meeting and he rewarded them with a fine third place amongst a sea of trick TZ Yamaha’s.

It would be easy to form the opinion that throughout it´s five-year reign, and the sheer amount of riders who made their name in the saddle of the marque, the TR750 was produced in considerable numbers, but nothing could be further than the truth. The TR was never commercially available and as few as forty were built in the four year period following 1972.

In America the “surplus to requirement” works Suzuki triples were crushed and buried, while in the UK a few factory triples carried on in private hands (Carl Fogarty’s dad George ran one for a season or so in the UK).

The ex Sheene machine seen here is the final incarnation of the XR11 with its Maxton inspired ’lowboy’ frame and slanted rear shocks, giving more progressive travel and adjustment. This bike is still in occasional use today, so a few concessions have been made to make such `demo rides´ that bit safer, like the junking of the Tokico front brake calipers in favour of the superior performing, albeit mechanically identical, Lockheed items.

The Suzuki RG500
The blue and white XR 14 is probably better known to the biking world as an RG500, but strictly speaking, that is incorrect, as this example is a pukka factory machine from 1975, not the production version available to all and sundry from 1976.

In fact this actual machine is the very one upon which Sheene scored his first ever 500 GP win at Assen 1975. There is little doubt amongst the racing fraternity that, were it not for his horrendous 175mph crash, while testing the XR11 in readiness for the Daytona 200 earlier that same year, then Sheene would have scooped his first 500 title back in `75. In spite of the tremendous recovery he made following that much publicised incident, the terrible injuries he sustained prevented him from scoring in two of the GPs and he had to wait until 76 for the first of his two world titles. Once fully fit, Sheene was dominant, convincingly winning the majority of GPs in that first title season.

Two strokes were very much a rarity on the big capacity GP scene of the early 70s, the bulk of machines being based heavily upon road going designs like the T500 Suzuki twin and the H1500 Kawasaki triple. Giacomo Agostini and the all-conquering MV Agusta four stroke still reigned supreme at GP level. Surprisingly, the screaming straight four MV carried on winning for the first half of the decade in spite of the strong technological advances being made by both Yamaha and Suzuki.

The square four, disc valve engine design was radical in 500 racing when launched in 1974, but in fact was based heavily upon the 125 and 250 four racers that the Suzuki factory campaigned in the sixties. Disc valve two stroke induction was itself a bit of 1950s racing technology, which Ernst Degner from MZ brought to Tokyo, when he defected from communist East Germany in the early 1960s. Initially the new RG500 handled badly, due to the engine being used as a stressed member but Maxton´s Ron Williams was enlisted to create a full loop frame design and much stronger swing arm set up. The rest, as they say, is history.

The first examples of the XR14 produced around 100bhp, with power steadily increasing with every new season and the output topping 120bhp some two years later. Initially the barrel featured only four transfer ports but by `76 these had been enlarged and made into no less than seven, hence the dramatic increase in power.
The engine and most of the cycle parts were of magnesium construction wherever possible, making the factory version a very light machine indeed, weighing in at 135 kgs Amazingly, this was 5kgs lighter than the twin cylinder machine it actually replaced. Much of the XR14´s success can be laid at the feet of Sheene and his tuning guru Father, Frank. Both Father and son were highly respected developers of two-stroke race machinery and this knowledge was put to good effect by the Suzuki factory.

The XR14 grew into the more compact stepped engine layout of the XR22 of 1978 and later the XR27 that kept the design still competitive at world level, well into the eighties. Randy Mamola made his GP debut in 1979 on the RG500, giving Roberts and Sheene a very close run, repeating the feat in 1980. Valentino Rossi´s dad Graziano rode one to 5th overall in the 1980 500cc world championship, whilst Marco Luchinelli broke Kenny Roberts run of 500GP titles in `81 aboard a Suzuki, with Franco Uncini doing it again on a Suzy in 82.

A big bore, 700cc version producing a whopping 154bhp, was developed by the UK based Heron team to replace the 750-3 during the 1977 season. Formula 750 racing was big business in the late seventies and the 500cc machines were not eligible. This bigger capacity machine brought the Suzuki teams back onto level pegging with the, over-the-counter TZ750 Yam, upon which virtually every privateer in the racing world was now mounted.

It was the RG500 which had the greater run of success however, as the F750 World championship finished after the 1979 season. The RG500 was a competitive bike in the 500cc class for almost a decade, from `76 to around `84. It was still a decent racebike in the mid 80s, especially for privateers, who had no chance of getting the new factory Yamaha V4s or Honda triples – regardless of how much sponsorship cash they had.

This success inspired Suzuki to build a roadgoing version of the RG500, which featured the same cassette style gearbox (so you could change ratios for your favourite roundabout), trick little 16 inch front wheel, aluminium twin-spar frame and state-of-art multi adjustable suspension, featuring anti-dive forks. With very little weight, the RG500 was capable of topping 150mph – if the rider had the balls to handle something close to a racing motorcycle.

The RG500 was heady stuff for 1984 and most road tests of the time rated it as being the better bike than rivals like the Yamaha RD500 YPVS, or Honda´s incredibly tiny (and rather fragile) NS400 triple. All the 1980s two strokes were totally impractical machines however, returning around 20mpg on average and requiring expert maintenance to stay in top tune.

A smaller RG400 was also produced for the Japanese domestic market, many of which can be found in grey import warehouses even today. Sadly, it isn´t built to the same high level of performance, or durability of the original RG500 and so is unlikely to be as collectable.

The 1998 Assen Centennial was a celebration of classic GP road racing, from the 1950s to the 1980s, put together by Ferry Brouwer, head man at Arai Europe and ex mechanic for Phil Read.

The weekend was incredibly hot and it was a bit hard on some of the classic road racing machines which were there. Graeme Crosby, Randy Mamola and Barry Sheene were all on various RG500 Suzukis. It was amazing to see the reaction of the crowd whenever Sheene showed his face outside the pit garage – only Agostini was equally mobbed by press and public alike.

It was a strange moment on the grid before the start of the 500cc `demo ride´ for the 1970s GP class, to see small knots of photographers gathered around Sheene and Mamola, whilst Kiwi Graeme Crosby was virtually ignored. I recall wandering over to Croz and saying I remembered seeing him race at Donington back in the early 80s.

“Cheers mate,” he replied, “I think you´re the only bloke here today who does.”

Sheene was riding a blue and white RG500 from the mid 70s that weekend, which was reluctant to work properly, constantly spluttering and misfiring. He would listen to the bike, revving it for a while, then blast up and down pitlane a few times, trying to suss out what was wrong with it. In fact, one journo asked him directly what the problem was with the bike, to which Sheene replied; “I think it´s f***ed mate.”

Nevertheless, when Sunday´s `demo ride´ against Mamola, Crosby, Hartog and others came around, Sheene got the bike working reasonably well, running steadily in 4th or 5th place, whilst Hartog and Mamola went all out for a crowd-pleasing `win.´ Hartog was still very impressive and it´s a testament to how good the over-the-counter RG500s were in the late 70s that this `flying farmer´ from Holland was able to achieve podium positions in GP 500 racing on a pivateer machine.

Mamola and Crosby definitely had smoother rides on their RG500s, partly because they were later model Heron Suzuki RG500s from the late 70s/early 80s, but also because ex-GP factory mechanic Martyn Ogbourne was prepping the two red/yellow Suzukis for the track. Both machines simply sounded crisper than Sheene´s, which allowed Mamola to entertain the Assen grandstand with some outstanding wheelies.

Although Mamola could still play the clown, his riding that day was awesome on that old RG500. When he decided to go fast, there really was only Wil Hartog who was capable of giving him a real race. For me, Randy still had the take-no-prisoners style of the 19 year old kid I first seen blitzing the opposition in a Transatlantic race at Oulton Park in `79.

Although he never won a world 500cc GP title, if ever a rider could have won a world championship through sheer grit, and crowd popularity, then Mamola was the man – pure motorcycling entertainment.

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Vital Statistics
Engine Square four cylinder, water cooled, two stroke
Cycle parts
Bore and stroke; N/A
Compression ratio; N/A
Gears; 6 speed, cassette type