Buzz Bombs and Two Stroke Wars Part 2

From 1961 on Suzuki's powerful two-strokes dominated GP motorcycle racing. 

 

Star rider Degner crashed at Honda's Suzuka Circuit. Oxley says he was a "different person after the 1963 crash" and retirement.

Undeterred Suzuki pressed on winning GP races, successfully competing against Honda's precise 4-strokes.  

RC145 125cc 4-cyl. 28 bhp @ 19,000 rpm

Devising amazing GP bikes Soichiro Honda fought back hard in 1964. Not content to be also-rans in grand prix racing Kawasaki and Yamaha stepped up their R & D efforts. But without a competitive machine Kawasaki wasn't in the game until the late sixties.

 1965 Season

Meanwhile, despite having superior bikes MZ (Degner's old employer) seemed unable to get on the podium against newcomer Yamaha.

1965 Suzuki water-cooled 30hp 125 RT64

Suzuki two-cylinder, two-stroke, with rotating-disk distribution. 
Displacement 123.7 cc. (43 mm. x 42.6 mm.)

1966-67: Two-stroke "buzz bomb" racers were now generating in excess of 200 bhp per liter of displacement, or twice the power of most street bikes.   

Not to be outdone Yamaha upped the ante by making their production racers available to privateers. 

1966 Yamaha RA97

30 BHP @ 14,000 rpm

1970 was a game changer for Japan. 
With public interest in affordable 2-strokes at all time high the Big Three were sitting on a goldmine. Research and development into faster bikes progressed at a furious pace. Sales of high-performing 2-strokes skyrocketed.

Even with it's phenomenal 250cc 58 hp racer DGR's MZ was having a hard time keeping up with Japan Inc. 

 

Yamaha's TD 2 began to dominate the racing scene. 

$1,800 to privateers

1970: Kawasaki's new two-stroke 3-cylinder 500-cc. H1 motorcycle with acceleration of 0-60 mph in 3 seconds changed everything overnight. Bear in mind this was a production motorcycle with 60 bhp available to anyone.

The genie being out of the bottle was creating havoc on city streets worldwide.

Kawasaki 500 H1RA racer

Nicknamed "The Flexi Flier" this lightweight 500cc bike was a genuine performance phenomenon, on and off the track.

Eager buyers were lining up at Big Three dealers in droves.

The H1 triple had set the bar for Kawasaki's rivals.

The Two Stroke Wars were on

Things were getting serious; millions of dollars in sales revenue was at stake. Riding the wave of popularity meant Suzuki & Yamaha also wanted their share.

1970-71: On the street Suzuki's new GT750 Triple with water-cooling packed them in. These were neat, if a bit heavy, touring bikes, built for the long haul. Mine was stone-axe reliable and fairly quick. 49-52 mpg fuel consumption was common.

1971 GT750 got high marks worldwide

Seeley TR750 Replica Custom

In 1971, championed by it's European dealers,Yamaha made a preemptive bid with a stillborn GL750, a liquid cooled, transverse 4 cyl. based on the TX750 chassis and hugging a TZ750 engine. It never made it into production. Most likely Yamaha leadership saw Honda's GL name looming on the horizon. That, plus tightening emissions standards killed off what could have been an impressive machine.

Yes this is Kenny Roberts' tracker TZ750

During this period high-performance design features flowed to Yamaha's highly popular R series street machines.

1971 R5

On the starting grid: 1971 TD3

TD3 250cc 49 hp

 
1972 TR3 350 

Air Cooled 6 speeds, 347cc 54 h.p. @ 9,500 r.p.m.

Last of the air cooled racers




Yamaha's TZ250-350 racers weighed around 200 lbs.

TZs were light & fast 140 mph (250) to 150 mph (350cc)

Honda Racing withdraws from GP racing 1968

Following their success in racing 4-stroke bikes and becoming a worldwide seller of motorcycles Honda Motor bowed out of GP racing in 1968. FIM restrictions on multi-cylinder engines revved to 22,000 rpms encouraged staying at home. Over the next two years Honda's RSC continued to provide spares / racing kits to privateers in small increments. Finally in 1970 Honda's wing-imprinted racers were back on track appearing at Daytona as four strokes.

Dick Mann won the 200 mile race on a CR750. 

Honda's 500 lb. CB750 four piper arguably invented the modern four-stroke super bike in 1969. 

Mann's Daytona CR750 based on CB750

With their potent CB/CR750 multis Honda was back

Suzuki Racing 1971 forward

With Suzuki's withdrawal from racing in 1968 the field was left to privateers and distributors using ex works machines. "Australia’s Jack Findlay became the first rider to win a 500 GP on a two-stroke machine when he won the 1971 Ulster GP at Dundrod – using a converted Suzuki T500 road-bike engine." The TR500 was a liquid-cooled version of their T500.

The Italians [Saiad] were notable for successfully campaigning modified production bikes into the mid seventies. With the advent of the new RG500 racer Suzuki was back, piloted by future racing super star Barry Sheene.

XR14 / RG500

The RG500 was THE GP bike that made racing history and forced Honda Motor to build 2-stroke racers. 

With its 200 bhp per liter & spindly frame the 1974 XR14 500cc racer was a force to be reckoned with. It was fast, very fast. Barry Sheene's circuit average was 217.37 km/h set in 1977. 
Originally designed as a racer it had few, if any, compromises to it's purpose, to win races.  An outgrowth of Kaaden's 2-stroke design philosophy, the RG500 was 4 MZ-like 125 cylinders set in square format with water cooling. Prone to sudden seizures Suzuki's riders had a love-hate relationship with their temperamental machines.

RG500

Suzuki wins in 1971-73 AMA racing

 
In the 1971-73 AMA Superbike series Suzuki had a winner with their TR750 (738cc) based on the GT750 production bike. Under the skin the TR racer bore a superficial resemblance to a GT750. A well-tuned TR was capable of 160 mph in full race mode.

TR750 triple racer

GT750 was a smooth rugged bike

AMA Super bike & GP Racing 1973-On

Honda vs Suzuki vs Kawasaki

Honda now had their CR750 4-stroke, Suzuki their TR750 2-stroke, while Kawasaki fielded a purpose-built KR750 [Mach IV 750 based] 2-stroke to run in the Daytona 200. 

All three racers were producing approx. 110-120 bhp

While the first CR750 had minor issues, the high-powered triples had trouble keeping tires & chains intact.

FIM & GP Racing 

In 500 GP Kawasaki fielded the H1r500 and H2r500 Triples. 

With an A for persistence Kawasaki had it's work cut out running hard against Suzuki & Yamaha's now-legendary GP machines. Though the Kawas were technically brilliant and well-tuned they met with limited success against Yamaha's TZ700-750 racer.
Even though the KR750 achieved 185 mph with more horsepower it couldn't surpass the winning tide from Suzuki & arch-rival Yamaha.

1976 FIM & AMA Superbike Racing 

Kawasaki raised the stakes with an improved KR750 Daytona with a new frame and more powerful engine. Gary Nixon piloted the now more competitive racer on the international circuit. Though he handled it magnificently Nixon was aced out of the FIM 750 Championship. 


Bit by bit the focus was shifting from reasonably priced 750cc 2-strokes to the new four stroke large displacement street bikes. The Big Three were also making more money from the new machines. In 1977 Suzuki introduced their four stroke GS750 model. Honda had the CB750 & Gold Wing. In 1976 Kawasaki introduced the KZ900 A4. Suddenly interest in street model 2-strokes was dissipating like blue smoke.

The KZ900 production bike was also adapted and campaigned by privateers. 

"From 1973 to 1975, the AMA called the fledgling Superbike class “Production Superbike.” In 1976, the class morphed into the moniker we know today – Superbike. And it became a true Championship series, albeit a support class to the well-known F1 category, which hosted bikes such as TZ750s, TZ500s and Honda’s trick, 3-cylinder RS500.

In Superbike’s early days, European machinery faired well, especially the Butler & Smith BMWs, which featured the vast experience and skills of Udo Gietil and the great fabricator Todd Schuster. The pair began working together in the late 1960s for New Jersey BMW Importer B&S. Englishman-turned-Californian Reg Pridmore won the first AMA Superbike Championship in 1976 on a Butler & Smith Beemer."

Brian O'Shea

It's best to let someone else tell AMA Superbike history.

Buzz Bombs & Two Stroke Wars - A History

We're in the best place; a Motorcycle Racing blog. This article surveys about 25 years of Grand Prix racing history from1961 to 1986. It also talks about the extraordinary role of a genius engineer and team manager, Walter Kaaden, ex-Hitler Youth member from the GDR, who gave the racing world incredibly powerful 2-stroke engines.

The 2010 book "Stealing Speed" by author and ex-racer Mat Oxley is an excellent source point for this article. The facts e.g. results of Kaaden's R and D work are fairly well known. What is not known is the 'how' of the scandal. Do read this exciting book about how Ernst Degner, MZ's star GP racer, stole and sold Kaaden's secrets.

Engineer Kaaden (L) and racer Degner (R)

Its also the dramatic story of East Germany's young World Championship GP racer and top mechanic, Ernst Degner, in short form, via short quotes from Mat Oxley's outstanding book. 

Membership was required

  
As a talented  engineer Kaaden worked for Prof. Herbert Wagner on the Hs293 Rocket Assisted Bomb, one of  Germany's most advanced weapons of WW2. 

Oxley says; "It wasn't  as if he had a choice." 

   





After WWII Walter Kaaden found employment at resurrected DKW, soon to be called MZ, in East Germany [GDR]. MZ became a communist state controlled manufacturing enterprise building motorcycles for a transport starved east block country..

Kaaden's  Expansion Chambers

Along with his power-improving expansion chamber Kaaden developed racing innovations; case reed carburetors and disc valves. Fuel is inducted into the loop scavanged crankcase making a 2-stroke engine more efficient. 

Kaaden's highly effective two stroke development work was top secret and was kept under wraps. The reasons were simple; MZ's engines were now producing an astounding 200 bhp per liter. With Kaaden and Degner on board the state had a winner.

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Kaaden's secret exhaust 'pulse' chamber

Case Reed Induction

Suffice to say, GP racer and future World Champion, Ernst Degner got loose from East Germany's clutches.

After Degner's defection Suzuki used Kaaden's engine secrets and became the dominant force in GP motorcycle racing for decades.

The remainder of this survey article is about subsequent events; how arch-rival Kawasaki copied Suzuki's engine hardware and became a serious threat on GP racetracks worldwide. 

Thus began the high performance two-stroke war fought on every major racetrack and on city streets until ever-tightening emissions standards spelled the end of 2-strokes.

The bike that started it all: DKW 125-3 aka the MZ125. Copied by BSA as the Bantam,  copied by Harley, by the Russians et. al. This was Kaaden's bread & butter machine.

 

By 1961 Kaaden had a winner with his air-cooled 125 cc racer developing an unheard of 25 h.p. MZ crew members made sure no-one got too close to the buzzing 2-stroke machines "with a powerband like a light switch."

  

MZ went to Liquid Cooling after 1961

 

Degner aboard peaky 50cc racer

Degner won '62 Isle of Man TT

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Suzuki's Anderson won 1963 Isle of Man TT, Degner was 3rd.