Historically the XR14’s life began way back in the mid sixties when racing machinery was exotic to say the least. Four, five and six cylinder motorcycles, with double figure gearbox ratios, filled the GP grids of all capacity classes even the 50’s.
Following the FIM rule changes, restricting the amount of cylinders and gears in each class, the grids were robbed of such Japanese exotica. Consequently for a five-year period spanning the sixties and seventies, the bulk of the GP grids were made up of either outdated big singles, or converted road engines housed in race chassis. This of course led to total domination of the premier class by big budget MV Agusta team, as the various other machines no matter how well developed could only really challenge for the runner up positions. What we did see before 1973 was a plethora of ingenious designs varying from the H1R Kawasaki and XR05 (TR500) Suzuki to the outboard motor powered, Konig. These designs were reliable and good enough whenever the MV, or Agostini failed to finish however, especially with riders of the calibre of Australian Jack Findlay and Brit Dave Simmons riding them.
Yamaha broke the mould in 1973 when with the help of the late Jarno Saarinen they took the world by storm, winning the first two GP’s straight out of the crate with their all singing all dancing four cylinder two stroke. The 73 title was not to be Yamaha’s however as Saarinen was tragically killed mid season and Yamaha withdrew from competition for the remainder of the year. Suzuki began development of their new 500 around about the mid point of that season and very much in secret enlisted new boy Barry Sheene to head the development team in readiness for a serious assault in 1974.
While the other designs fell by the wayside the XR05 twin continued to be run for the 73 and 74 season enabling the XR14 designer Makoto Hase to assess the opposition, he acquired much data that season in readiness for his new project. It comes as no surprise to discover that Hase was also the designer of the square four 125 and 250 Suzuki’s from the sixties. The very successful four cylinder RS67 125cc Suzuki led to the not so victorious RZ65 250 version. Known as the whispering death due to it’s ability to seize without the usual warning signs the 250 square four never finished higher than third throughout it’s short career and the project was shelved after only one season.
First publicly seen in 1974 ridden by Sheene and the Australian Jack Findlay the 500 square four broke the current mould in the premier class and along with the Yamaha sounded the death knell for the then dominant four stroke racers. Although the writing was on the wall MV did not give up, their perseverance and technical knowledge kept the 100BHP four cylinder four stroke competitive for a further two years actually winning the title with Phil Read in 1974 and finishing a close second behind Yamaha mounted Giacomo Agostini (Read actually scored more points that year but the final score was based on the best eight out of ten rounds hence Ago was crowned champ).
It is fair to say that initially the XR14 was not a pretty machine with its upright shock absorbers and lumpy fairing required to shroud the protruding carburettors. By 1975 the XR had become a little more pleasing to the eye with laid down shocks and a smoother look to the fairing. Early models of the XR14 also shared the RZ65’s frightening ability to seize and on several occasions test riders were thrown unceremoniously up the track.
In an effort to reduce frontal area the original frame design had no down tubes and lower rails, this meant the exhausts and belly pan could sit much higher off the ground. As well as being mounted at the rear, the engine hung by a large aluminium bracket attached to the cylinder heads. This design worked well at the Suzuki test track but when the bike was run on the fast and sometimes-bumpy GP circuits in the heat of competition it handled badly and soon separate down tubes were attached to strengthen the frame. Eventually a full loop frame, the third different one in under a year, designed by Ron Williams of Maxton engineering would be utilised for the remainder of 74, this chassis transformed the XR and the following RG series of machines.
Yamaha had the advantage of a long development period with their four-cylinder design having been committed to development and production since 1971, the radical reed valve two-stroke having been tested extensively throughout the two years before it’s debut in 73. The Suzuki equivalent was not so fortunate and hit the racetrack in a shade over six months from its inception. This showed in the teething troubles encountered and the extensive redesigning of several aspects of the machine. The test riders agreed to a man however that the XR14 was very fast, certainly faster than the 750 triple machine that Suzuki were running in the Superbike classes.
The engine vibrated considerably and in the first year many of the external bits cracked and fell off, many a race was ended prematurely when the Suzuki shed its gear lever or some such crucial extremity. In Sweden during that first season Sheene was in the lead and well on his way to the XR14’s first GP win when the water pump seized. This high sided the hapless Sheene and the first win would have to wait till another time. Once again whilst in the lead in Italy the gearbox seized and spat him up the road. At the 1974 Dutch TT, Sheene was again well up on the leaderboard when a vibration warned him of an impending gearbox failure, after much deliberation he decided to take the soft option and pull in. Upon inspection it was discovered that true to Sheene’s on board diagnosis a shaft had sheared its mounting bolts making it the equivalent of an unexploded bomb within the engine. Suzuki where geared up for quick changes and before the next GP, only a fortnight away, an engineer had returned to the Japanese factory and manufactured four new shafts out of solid steel billet. These were fitted in time for the race and that part never gave a problem again.
A bitter pill for Sheene and the Suzuki team must have been at the Belgium GP in that all important first season. Sheene had knocked twelve seconds off his best ever lap time around the Spa Francorchamps circuit and at mid distance was lying comfortable behind the race leader, MV mounted Phil Read, the Suzuki’s gear linkage fractured forcing Sheene to retire. The XR14/ Sheene combination was competitive there was no doubt about that but it just would not stay together long enough to win races.
1975 arrived and Suzuki put together a very strong two man team of Sheene and Tepi Lansivouri, it was also strongly rumoured at the time that the reigning 500 World Champ Phil Read would defect from MV to join the team but last minute negotiations saw him remain on the Italian four stroke for another year. Sheene was confident in the run up to the 75 GP season, he had spent much time testing the XR14 through the previous winter, ironing out those troublesome little problems that had caused so many retirements the season before. The new frame handled well and the extensive testing had yielded even more power so the cockney rider had every right to feel sure of the 500 title. Other more obvious modifications was the laying down of the rear shocks, giving more travel along with finer adjustment and the replacement of the round tube swing arm, a hefty box section unit now provided the required strength. There had been problems with crankshaft failure but this was cured by the fitting of an oil pump driven off the front right hand primary gear and force feeding oil to the individual bearings. The oil tank was placed high up in the seat hump, clearly indicated by the presence of a white plastic screw cap.
We all know the problems that beset Sheene at the start of that year, the 175mph Daytona crash saw him with severe injuries, really putting paid to any serious title challenge. Sheene’s body was very badly damaged but, none the less he made it to the track to practise for the Austrian GP just six weeks after that terrible crash. Sheene qualified sixth for the race but despite proving he could push start the XR he was prevented from riding by the officials. Following the Belgium GP on the super fast Chimay circuit there was a five week lay off in the schedule that allowed Barry some desperately needed convalescence and it was a much fitter Sheene who arrived at Assen for the Dutch TT. In the race Sheene tagged on to Yamaha mounted Ago, passing him exiting the last corner on the very last lap to take his and Suzuki’s first, and desperately needed, 500 GP win.
Things were looking good for Sheene in 1976 so it must have been quite a shock to him when Suzuki totally withdrew their support at the beginning of that season. The new range of GS road machines where about to be developed and the factory wanted to concentrate on this. Sheene and the other riders were left high and dry until UK importers, Suzuki GB, stepped in with the offer of running the GP squad. Thankfully this was agreed and Heron Suzuki GB took on the full responsibility of the Grand Prix campaign.
Such was the progress made in performance that the Sheene 1975 XR14, like it’s 1974 predecessor, was almost obsolete within a season. The 1974/75 XR14 featured an over square and peaky, short stroke engine, by 76 it had become a fat square 54 x 54 for the top rider while the other team members, John Newbold and John Williams, had to make do with the slower yet more revvy engine configuration. The 54 x 54 engine produced precious little extra horse power but did give a much wider spread of power making it easier to ride throughout the long distances encountered in a GP race.
The XR 14 of 1976 had seven port barrels instead of the original five, weighed 8kgs less and possessed a top speed over 8mph faster through the Suzuki test track speed trap. The oil pump was removed following extensive modification to the crank material and the subsequent improvement in reliability. Sheene made certain that no other Suzuki team member got his hands on the latest specification tackle and this was the cause of much unrest within the Heron Suzuki squad. There are various reports and allegations of Sheene personnel meeting trucks in the middle of the night to get the latest spares out before they reached the circuit and many more cunning tactics. To make matters worse Sheene once lent one of his three race machines to the talented French privateer Michel Rougerie. Rougerie had been struggling to qualify due to technical difficulties, using Sheene’s machine he did indeed qualify, in fourth ahead of, and much to the chagrin of, the other Heron team members, this did not help the already rocky situation that was in existence within the team.
From the very start of the 76 GP season the majority of the 500 grid was Suzuki mounted either on official factory XR machines or on the over the counter RG500. This production machine was available to all who had the £5000 asking price, not bad for a very competitive GP bike. Suzuki was quite unique in this respect as Yamaha did not produce a customer version of the OW series of 500 racers until 1980 and even then it was in no way a competitive racer. The only alternative facing the non-Suzuki mounted privateer would have been to convert a TZ750 into a 500 by using TZ250 barrels. Surprisingly although this combination worked well in the sidecar world this was never a successful union in a solo as it created a peaky, difficult to handle machine that was in reality actually slower than a big bore TZ350.
Even though the Mk1 RG was built to the original 75 specifications several determined riders and tuners made good use of their square fours often giving a good chase if not beating the factory boys. At the very first GP of the 76 season, privateer and future 500 champ, Marco Lucchinelli romped home to a stunning third place on a production specification RG500.
That first championship-winning year was not all plain sailing for Sheene, while testing at his local track, Snetterton the front brake pads jumped out at the end of the super fast straight and the cockney rider had no option but to run into the grass bank at full tilt. A mechanic had omitted the retaining pins enabling the pads to simply drop out. Luckily Sheene walked away from this incident relatively unscathed which was just as well as the team only had to finish in the top five at the Swedish GP the following weekend to clinch the title. Imagine the state of Sheene’s mind when virtually the same problem occurred at that meeting. Sheene was ready to go out for practise when he noticed that one brake pad had been assembled incorrectly with the pad surface actually facing away from the disc. There is no doubt that the tremendous pressure was getting to the whole team as that weekend Sheene’s number one machine, following that test crash at Snetterton, had been rebuilt with the wrong front end. Like wise his number two machine had the wrong gearbox fitted and Michelin had sent him tyres that were completely useless. None the less these problems were sorted, Sheene romped home to win the Swedish GP and with it his and Suzuki’s first 500 title.
By the end of the hard fought 76 season not only had Sheene been crowned World Champion but the whole of the top twelve in the final standings where either RG500 or XR14 mounted. 1976 also saw the very last four stroke GP win when Ago, who had ridden both the MV and an over the counter RG that season, won the German GP on the screaming Italian four.
Sheene went on to win the 500 title for a second time in 77 but the following three years saw the total dominance of Yamaha and the Californian Kenny Roberts. The Suzuki square four did make a jubilant return however when first Marco Lucchinelli and then Franco Uncini, both riding for the Italian Gallina Suzuki team reigned supreme throughout 1981/82.
The RG500 became such a benchmark for 500cc GP racing in the late 70’s that when Honda began their return to scene the race department purchased a new one, no doubt through a third party, to use as a direct comparison when developing the NR500 V oval piston four cylinder GP racer. The XR works machines, along with the over the counter RG production versions, carried on in development for some nine years after it’s GP debut and in private development for many seasons after that. The factory pulled out officially in 1984, handing over the manufacturing rights of the RG to the Padgetts concern, while the Japanese went away to develop the V four Gamma series that saw title success with Kevin Schwantz in 1994 and Kenny Roberts jnr in 2000.
The RG500 also broke a long standing record, held previously by the Manx Norton, for the most GP wins, particularly impressive when you look how long the Norton was in production compared to the nine years or so of the Suzuki.
Barry Sheene’s XR Tech Specification;
This machine was found as a box of bits and it was only when the records of Suzuki GB were checked that it revealed it’s former life. Chassis number G56-1026 is one of two machines Barry Sheene competed on in 1975 and the actual one upon which he scored his first ever 500 GP win. Barry himself has confirmed the authenticity of the XR14 when he rode the machine at the recent Assen centennial and his signature now adorns the petrol tank giving his personal endorsement to the works racer.
The bike was purchased in a very sorry state indeed and no one could have imagined its importance to British racing history until the restoration fully got underway. Renowned restorer and ex factory mechanic Nigel Everett is the man responsible for the work and he used his knowledge to faithfully rebuild the machine to the specification it ran in when Barry used it. The machine was used the following season for the other team members but not by Sheene as he had the very latest specification engines and chassis, which proved far superior to the 75 spec machines. Power output was quoted in 1975 as 100bhp @10700rpm and following the extensive rebuild it showed 101bhp on Nigel’s dyno. This resulted in a top speed in excess of 175mph. The majority of the XR14 was originally magnesium but following a series of engine mishaps caused by porous casings Sheene used heavier but more reliable aluminium castings and these are still present today.
The engine is a true square four design with individual crankshafts driving two jackshafts before transmitting the power on to the clutch and gearbox. The main jackshaft ran the full width of the engine driving the tacho drive, oil pump and clutch on the right and running the Nippon Denso CDI ignition system situated under the left hand carburettors. The square four arrangement lasted until the development of the stepped cylinder XR23 in 1978. This was a big bore version of the 500 and enabled Suzuki to compete in the 750cc Superbike class, the extra power on tap also pushed forward the all too necessary chassis development.
The extra room required for the bigger engine components meant the crankshafts had to be tilted upwards and away from the six-speed gearbox and this actually resulted in a shorter more compact engine with a lower centre of gravity. Much weight was saved with the later design as it could be produced in two, rather than three separate castings. A by-product of this was the creation of more room behind the cranks enabling the designers to incorporate both the big capacity engine and the 500cc version with a cassette type quickly detachable gearbox. The whole of the gearbox on the later model can be removed in minutes, simply by removing the clutch and outer casing, enabling the use of a vast choice of different ratios for varying conditions. Later versions of the XR, 1978 onward, also saw improvement in strength and space saving with the use of two one-piece cranks instead of the four individual units used earlier.
Situated on the end of each crankshaft are the disc valves each with it’s own magnesium bodied 34mm Mikuni carburettor. The carburettors are operated by four individual cables, all directly pulled by the twist grip. Unusually the five port cylinders are iron lined rather than the original chrome bores favoured by the Japanese. Sheene preferred the iron liners as he felt they were less likely to seize suddenly and although much heavier they were also far easier to work with should any porting work be required or cleaning up needed following a mishap. One of the main reasons Sheene was enlisted for the XR14 project was the extensive knowledge of racing two strokes possessed by the young racer and his, father Frank. Much of the early success can be directly attributed to their expertise, Sheene was very nearly 125cc World Champion in 1971 on an almost obsolete Suzuki twin, if it was a two stroke they could make it go.
One area where the Japanese were sadly lacking was carburettor set up and the Suzuki machines invariably left the factory way too rich. This led to many plug problems during the early races until the Japanese mechanics were finally persuaded to come down on jet sizes, unlocking the extra available horsepower in the process. This set up problem was greatly exacerbated by the disc valve engines natural tendency to appear lean when in actual fact it is way too rich.
On more than one occasion Sheene’s vast mechanical knowledge and empathy with his machine has saved the day, either during a race or during testing when he could feel a vibration and instantly know what it was. Barry always has attributed the loss of a third 500 title to the constant confrontation with official Suzuki mechanics, the factory had made its return to the scene following the two seasons of almost private running. This culminated in a situation at the Finnish GP when, during practise, he correctly reported a failing main bearing before the crucial championship race. The Japanese crew did not think it likely based on the recorded mileages for that particular engine so steadfastly refused to strip the engine. Barry was totally vindicated when that exact main bearing failed during the race, however the cockney scored no points that day and Kenny Roberts won the title race. That kind of mechanical sympathy and know how is very hard to find especially in a talented racer.
Chassis wise the early XR is nothing particularly special with it’s twin shock rear suspension and conventional front forks, while Yamaha and MV Agusta were experimenting with varying types of monoshock and long travel systems. The XR14 would have been equipped with Kayaba rear suspension units but due to the scarcity of such items they have been replaced with the superb Hagon shockers. The spindly steel tube frame fits neatly around the compact engine unit to create a very narrow machine indeed.
One area that Suzuki was constantly developing was the braking efficiency and the first XR14’s arrived with ultra lightweight plasma coated aluminium discs. While the discs dramatically reduced the gyroscopic forces on the front wheel they did not perform satisfactorily and Sheene ran stainless steel discs with Tokico copies of the ubiquitous Lockheed calipers providing the stopping power. All of the Sheene Suzuki’s from the period feature the calipers mounted on to the front of the fork tubes, this was believed to offer better cooling due to the clear airflow but was a technique seldom used after this period as, among other things, it made the steering very heavy under braking. This was purely personal preference however and should the calipers be required on the rear it was simply a matter of swapping the fork legs around from left to right. The fork legs are a mere 35mm in diameter, a size more commonly found on a scooter these days. A similar Tokico caliper provides rear stopping power, linked to the lower frame by a torque arm and grabbing a 270mm stainless steel vented disc.
Sheene is widely reported as saying that nothing in the XR14’s chassis department ever quite matched the power output of the engine, the thin steel tube frame flexed wildly under acceleration while the brakes never gave heart stopping performance. The XR14 was light however at some 135 kg, this was due mainly to a plethora of magnesium parts along with extensive use of titanium nuts and bolts. The Japanese were no doubt concentrating on the dyno figures more than anything else, later models of the XR recorded the highest ever power to weight ratio at that time from a Suzuki at 1034bhp per ton. The steering is a relatively lazy affair with a 29 degree head angle and a massive, by racing standards, 124mm of trail, this was all held together within a reasonably short 1375mm wheelbase giving, for the time, an adequate track agility.
Surprisingly the twin shock layout of the rear end lasted for quite some time being finally phased out on the factory bikes as late as 1980 and disappearing off the production models in 1982. As the years rolled on the chassis caught up with the engine output, the forks became thicker diameter, the frame grew beefier and in 1980 the rear suspension took on a more modern look with it’s rising rate single shock lay out.
Barry Sheen Suzuki XR14 Gallery