A Stroke Of Genius

In 1974, Suzuki changed the face of 500cc Grand Prix racing forever with the launch of the square-four RG500. Not only did this bike herald the arrival of the large-capacity two-stroke GP bike, but it went on to win seven consecutive 500 GP constructors’ championships, four world titles, 50 individual races, and allowed privateers to compete for GP glory on an equal footing with factory teams for the first time. What is even more remarkable is that this incredible machine wasn’t the result of millions of yen of investment and a huge R&D team; instead, the bike that gave Suzuki its first 500 GP crown and introduced the world to Barry Sheene was the brainchild of just four dedicated engineers.

“We started the project in 1973 with the target of being ready for the 1974 season and only had four people working on it—two for the engine and two for the chassis,” remembers Makoto “Big Mac” Suzuki, who, alongside Makoto Hase, developed the RG’s engine. “People thought we were crazy, as two-stroke engines were only used on small bikes, but the decision was made for us. That was all Suzuki knew; we didn’t build four-strokes. We looked at our small-capacity two-stroke bikes, and as we had already built square-four and V-4 125cc and 250cc racebikes, we simply decided to upsize them.”

While hindsight tells us that Suzuki’s decision to race a two-stroke was the right choice, in the early 1970s, the thought of entering the 500 class with a two-stroke motor was laughable. Italian firm MV Agusta was dominating the world with its four-stroke, taking 13 straight titles with Mike Hailwood, Giacomo Agostini, and Phil Read, and smokers were confined to the tiddler classes. Despite all this, in 1974 Suzuki lined up on the grid with Barry Sheene and Paul Smart riding brand-new 500cc two-stroke racers. Could they be competitive? Although the doubters were yet to be convinced, Suzuki’s race team personnel were confident, as they had made huge leaps forward in technology not only when it came to the revolutionary engine but also the RG500’s chassis. Yet one problem remained: Compared to the smooth power delivery of a four-stroke, taming the brutal two-stroke would require a lot of fine-tuning, not only from the rider but also the mechanics who were working on the bike at the track.

“With the RG we aimed for over 100 bhp, but it made 110 bhp in the end,” Suzuki-san says, “which would have been an issue for the chassis had we not been racing the XR11 in America. The XR11 was a 750cc triple with lots of power, so we had all the issues with this bike. In America we suffered torn tires, snapped drive chains, overwhelmed suspension—it was terrible. The chassis development was so far behind the engine. For the RG500 we used the knowledge from the XR11 to build a good chassis; however, the engine was still very hard to ride and peaky. The power was produced from 8,000 to 10,500 rpm—that was it—but the mechanics could alter these characteristics with exhausts and jets at the circuits. At that time there was a lot of experimentation and development happening. We were looking for inspiration from everywhere—even household items. The exhaust end-cans on the RG500 were modified green-tea cans. They looked the correct size, so I introduced this technology into the GP bike. The same tea company made the exhaust cans for the XR14 and updated XR22 model.”

Nowadays we are all used to seeing race engineers poring over reams of data in the pit box as they debrief a rider and study every minute detail about the bike. But in the 1970s the world was a very different place; data logging didn’t exist, and the most sophisticated piece of equipment was a stopwatch. Yet despite these technological barriers, Suzuki continued to refine and develop the RG500 from back in Japan between rounds, often flying new parts out to the tracks as hand luggage with one of the team members.

“There was no TV coverage of the racing in Japan, instead we read reports,” Suzuki-san remembers. “After each race the engineers and riders would sit down and hand-write pages and pages of notes on the bike’s performance and where it could be improved. These would be faxed or telexed to Japan, and I would have to imagine the issues and what they wanted. The mechanics were very hands on, which is why it was important to have experienced engineers who could come up with solutions and test them at the track. They would even cut disc valves with scissors to see if they could alter the performance. Most of the time I would look at the notes and think they were mad, but I had to trust what they said would work. My job was to take their ideas and make them reliable.”

Thanks to this dedication, success was quick to arrive for the RG500, and in its debut year Barry Sheene rode the XR14 to its, and Suzuki’s, first 500 GP win when he took the checkered flag at the Assen GP. Two years later he brought Suzuki its first 500 GP world title; for the RG’s development team, however, it was the constructors’ title that came alongside the riders’ title that meant the most.

With the RG500, Suzuki made a radical decision: The company would release a privateer bike that was identical in specification to the factory machines. The reason? With a grid full of RGs, the sought-after constructors’ title was all but assured.

“For Suzuki the most important thing was the constructors’ championship, not the riders’ one,” Suzuki-san says with a laugh. “If your rider wins, you can only say the rider is a world champion; if you win the constructors’ championship, you can say ‘Suzuki is world champion.’ This drove Barry mad. He would get very upset because the privateer bikes were identical to the factory ones! For Suzuki it was excellent. We won seven constructors’ championships in a row. And it was this philosophy that cemented the RG500’s place in GP racing’s history.

“The only difference was the fact the factory bikes had titanium or magnesium fasteners where the production bike had steel or aluminum ones,” Suzuki-san confirms. “The engine was 100-percent identical. We just changed the name from ‘prototype’ to ‘production.’ You could buy a production RG500 and win a GP, as Jack Middelburg did in 1981. That was the last time a privateer won a 500 GP; however, he rode an RG500 Mk VIII based on the XR22.” You can only imagine Sheene’s frustrations when he looked alongside him and saw privateer machines lining up on the grid. Or was overtaken by them on a straight…

With the 1976 and 1977 titles in the bag thanks to Sheene, in 1978 Suzuki faced tough competition from a resurgent Yamaha and upgraded the RG500 to the XR22 with its “step motor.” This engine used the first cassette gearbox on a motorcycle, a feature that is common to most engine designs nowadays but was radical technology in 1978 that required input from the McLaren Racing F1 team. However despite developing it in 1976, the gearbox didn’t see the light of day until 1978.

“Barry won the 1976 title on the XR14, but we held the XR22 back in 1977 in case Yamaha came out with something special,” Suzuki-san explains. “They only unveiled exhaust valves, and so we kept it hidden until 1978. Also, our customer RG500 XR14 was proving very popular, and we didn’t want to detract from it, though we also needed to beat it as privateer riders were starting to challenge the factory ones! People had developed their XR14s so well they were incredibly fast and more than capable of matching the XR22. The power was not so different with the XR22 when compared to the XR14. They both made around 124 bhp, however the engine was lighter, which made the bikes handle better. Weight was a big factor in GPs in the 1970s and 1980s, as despite there being a minimum weight of 100 kilograms [220 pounds] the bikes would never match this. The best we got was 108 kilograms [238 pounds]. With 124 bhp and 108 kilograms, the XR22 was quite a beast!

“I rode the XR22 for half a lap in Japan and only once—that was enough for me,” he continues. “I pulled out of the pits and rode around a 200-degree corner and the rev counter wasn’t even registering, as it started at 5,000 rpm. On the straight I opened the throttle, the revs suddenly appeared, the bike wheelied, and I pulled in. It was a terrible moment. I really appreciated the skill riders such as Barry Sheene had.”

Suzuki’s square-four design went on to dominate 500 GP racing, taking two more world titles (1981 with Marco Lucchinelli and 1982 with Franco Uncini) and winning a total of 50 races alongside the seven consecutive constructors’ championships. But everything has to come to an end, and in 1987 the square-four RG500 was replaced by the V-4 RGV500, a change that was inevitable due to the fact the competition was now following Suzuki’s lead and all using two-stroke motors.

“The square-four had very good weight distribution and a lot of power,” Suzuki-san explains. “It is a simple engine but one that was reliable and worked very well. However, it was limited in its power output, which is why it was replaced by the V-4. The inlet port was limited in space, however on a V-4 it is not. The more fuel and air you can get into an engine the more power you get out, which is why the introduction of the V-4 boosted power from 133 bhp to over 145 bhp instantly.”

By this time the veteran engineer was working on other projects within Suzuki, though none proved as fulfilling as developing the RG500, and he remained in close contact with the GP team.

“In 1982 I was asked to look after the four-stroke XR69,” he says. “I stayed for one year, worked on the motor’s reliability. We won the 1983 Suzuka 8 Hours race. Four-stroke engines were not as much fun as the two-strokes, and in 1983 I moved to work on the RM125 motocross bike, which is basically a quarter of the RG500 engine. Interestingly, the original XR14 used a 56 x 50mm bore and stroke, which was changed to 54 x 54mm. The original dimensions gave better power characteristics, but the equal bore was used on the motocrossers, and Suzuki wanted to keep this symmetry despite it not being ideal for roadracing. The motocross team’s R&D was located right next to the GP team’s in the same office in Japan, so I often spoke with the GP engineers.”

Having been involved during the glory years of 500 GP racing with such outgoing characters as Barry Sheene, Marco Lucchinelli, and Franco Uncini, Suzuki-san must have some very fond memories of this special period in Suzuki’s racing history. Despite shyly admitting to an incident involving a stone dragon, a company car, and Barry Sheene returning the vehicle to Suzuki with a collapsed roof, it is another story that raises the biggest smile and shows the team’s dedication to success. “One time we were working very late into the night and Barry arrived with a whole crate of beer at the R&D department and put it on top of the bike,” Suzuki-san says. “A photo was taken, and somehow it found its way into the weekly paper Motorcycle News. The bosses of Suzuki were not very impressed at all! The beer tasted very good…”