Passion, espionage, spills, thrills, loyalty and betrayal. Sound like the plot of a Hollywood movie? It should be, but actually it is a true-life story – one that took place under the black cloud of the Cold War and with the looming tempest of nuclear fallout in the background. This is the stranger-than-fiction story of how the humble two-stroke came out from behind the Iron Curtain and took over the world.

The two main characters of this story, Walter Kaaden and Ernst Degner, were two men who could not have been more different but were united by their common passion for motorbikes and squeezing every last drop of power out of them – one through masterful engineering and one through sheer riding talent. But their choices led them down very different paths.

Although Walter Kaaden was not the inventer of the two-stroke engine, many people consider him to the father of the modern two-stroke. He studied mechanical engineering while serving an apprenticeship at the DKW motorbike factory in Zschopau, Germany in the years leading up to WWII. When war broke out, he was sent to the Luftwaffe’s top-secret Peenemünde test site to develop the Nazis’ so-called ‘Vengeance Weapons’ – the V-1 and V-2.

After the war, he went home to Zschopau and started racing two-strokes, tinkering on them to make them go faster. The Communist authorities of East Germany noticed him zooting up and down and put him in charge of MZ’s new racing department. The facilities were basic at best and funding was virtually non-existent, but Kaaden and a handful of assistants toiled day and night to find the magic formula that would allow them to get maximum performance from the finicky two-stroke engine.

Despite the rest of the world believing that the days of the ‘two-smoke’ in racing were over, Kaaden refused to give up. Using knowledge he had gained at Peenemünde, he finally put the holy trinity together: expansion chamber, disc valve and boost port. The resulting MZ 125 was the first real threat to the then-dominating four-strokes and when, in 1956, Kaaden signed on 24-year-old East German rider Ernst Degner (a mechanic by trade), the gifted and intuitive rider seemed to know just what to do to make Kaaden’s two-strokes sing. Suddenly the rest of the world sat up and took notice of the odd little East German operation and their primitive-looking two-strokes.

Degner became East Germany’s chosen hero – the man who would bring glory to the communist nation and show those westerners a thing or two. But the gutsy rider had other plans. He was well aware that motorbike racers in the rest of the world were being paid handsomely for their services, evidenced by their lavish lifestyles. He had to make do with earning the same as any old worker on the factory floor – and even had to clean that floor like the rest of his colleagues. Not only that, but he hated living in the oppressive communist state, constantly under the evil eye of the dreaded Stasi – the secret police. Then, in an unlikely twist of fate, the stars aligned and created a chance for him and his young family to escape.

It was 1960, and the Japanese manufacturer Suzuki had just been horribly humiliated at the Isle of Mann 125 TT. Their competing 125s were embarrassingly slow: while race winner Carlo Ubbiali averaged 85mph on his MV four-stroke, Suzuki’s best finisher crossed the line 15 minutes later, with a measly 70mph average. Head honcho Shunzo Suzuki knew something drastic had to be done to prevent his company from becoming a complete laughingstock.

So Suzuki approached Degner and several secret meetings were set up. Eventually a deal was made: Suzuki would give him a job building competitive bikes and racing them. But it wasn’t just his expertise in riding or mechanical skill the Japanese were after, of course. The condition was that Degner would have to hand over the secret technology developed by Kaaden that would enable Suzuki to build race-winning machines. Degner agreed and had his own – rather large – financial condition. So it was decided – Degner would defect. That was the easy part; the really hard bit would be figuring out how to get out of East Germany alive.

So a plan was hatched: Degner’s wife Gerda and their two young kids would travel by train to West Berlin on the morning of 13 August, the day after Degner was due to race at the Ulster GP at Dundrod. But, in a plot twist that seems too fantastical to be true, the Degners woke up on the planned morning only to find out that overnight communist forces had begun construction of the Berlin Wall and the border was completely blocked! The Cold War was at its peak and the world was on the brink of nuclear obliteration, but this was the least of the Degners’ worries.

The daring escape plan had to be postponed and it was back to the drawing board. In desperation, Degner called on fellow racer, West German Paul Petry, to assist. Posing as a businessman, Petry began to regularly drive his massive Lincoln Mercury across the German border so that the border patrol would get to know him. It was decided that Gerda and the kids would cross the border to safety in a secret compartment which Petry had created in the gigantic boot of his car. During the weekend of the Swedish GP, while Degner was competing at the Swedish GP, his children were drugged and placed in the Lincoln’s boot, along with Gerda. Petry drove the car over the border and they made it to safety without any incident.

For Degner, however, plans went awry. He was at Kristianstad racetrack on the verge of winning the world championship when disaster struck. The MZ seized and his race was over. That night, he snuck away from his team and met a Suzuki representative who drove him (and a suitcase full of MZ engine parts and drawings he’d stolen) into Denmark. Although he was grateful to have made it to safety, in Degner’s mind – despite he and his family coming close to death and finally tasting freedom – the most important thing was still the world championship. He couldn’t bear getting so close and failing; he was determined to race in the season finale in Argentina. So he headed to the UK where he arranged to borrow an EMC two-stroke.

Whether it was sabotage as Degner believed or just bad luck, the bike never made it to Argentina. Defeated, he headed to Japan to start his new role for the Japanese manufacturer. There he spent six months slogging away in the Suzuki workshop. His contract stated that he had to help create a new 125 that was good for a minimum of 22hp in order to cash out his agreed-upon payout of £10 000. He got to that and more – the new Suzuki RT125 made 24hp. To ensure no one would think Suzuki had outright copied Kaaden’s design, their RT125 was a mirror-image of the MZ single. At the same time, a new RM 50 single and RV62 250 twin were also developed thanks to Kaaden’s technology.

As a result, Suzuki’s 1962 season was a far cry from the one two years before. The zippy new 50 scored Suzuki’s first-ever world championship point at Barcelona in May, then won the company’s first world championship race at the Isle of Man. Four months later, Degner nabbed the 50 world title in Argentina and Suzuki also won their first 125 GP. The once- beleaguered Japanese manufacturer was finally a serious contender and Degner was on top of the world.

But then Degner’s life took a nosedive. It began with a horrific crash in 1963 that resulted in severe facial burns. When he finally got back to racing in 1965, he shattered his leg at the Italian GP, and in 1966 he suffered head injuries at the Japanese GP. Sadly he spiralled into a deep depression, his relationships ended and he became addicted to pain killers. He died alone in 1981 at the age of just 53. His official cause of death was listed as a heart attack but there are those who believe that the Stasi got their final revenge…

And what became of poor Walter Kaaden? He could have become a bitter and twisted old man, angry that he was so cruelly betrayed and that his brilliant design was stolen and used, with no credit given to him. But he was very much a get-on-with-it sort of person, as his history demonstrates. Instead, he forgave his old colleague. I like to think he got some pleasure out of seeing how his passion and life’s work helped to build an industry. As for the two-stroke, it went on to completely dominate GP racing and ensured that four-strokes did not win a single world title after 1975.

Of course, the rules changed after that and in 2001 the MotoGP age began, where two-strokes were limited to 500cc while the four-strokes could measure in at 990cc. The result was that by 2003 there were no more two-strokes on the top tier world championship grid, but the reason behind the departure was not that Kaaden’s vision had been wrong. Rather, the motorcycle industry in general began to turn away from two-strokes as government regulations rendered them obsolete on the streets and manufacturers began to place more emphasis on four-stroke development that they could apply to their consumer models. Times may have changed but the impact of Kaaden’s genius lives on.

For the full story, check out the book Stealing Speed: The Biggest Spy Scandal in Motorsport History by Mat Oxley