15 Two-Strokes That Terrorised the Motorcycle World

This is sort of an extension to the Terrifying Bikes video, which I will link at the end. ,

This time, I will be focussing totally on two-strokes of all shapes and sizes, so strap yourself in for another wild ride.

I’m always interested to hear about the bikes you think I have missed too, but maybe check the video linked at the end to make sure they weren’t included there or in one of the other videos.

Also, I do still try to reply to everyone, but that is getting increasingly hard and I know I am getting behind on it, so if you didn’t get a reply to something I am sorry, I do my best, but sometimes even after spending several hours at it there are still many left unanswered.

Now I have said 15, and that’s sort of right depending how you group some of the bikes together. You will see why where I have done that at the beginning. Its just the way it worked this time. Putting them into any meaningful order is also a difficult one here because some of the bikes are very different, so there would be little purpose in any back to back comparison.

So I am just starting from the less surprising choices and moving on through the less well known motorcycles.

Suzuki T250, T20 Super Six, X6 Hustler,

First is a motorcycle that just missed out in the “Ton Up 250cc Motorcycles” video. The Suzuki T250, T20 Super Six and X6 Hustler are all grouped together here for obvious reasons. Although called the X6 Hustler, T20, T21 and Super T21 at various points in different countries, in Japan it was always known as the T250. This popular twin cylinder 250cc two-stroke was produced by Suzuki from 1966 to 1972 and sold even after that. It produced 33HP, which was actually 3HP more than the GT250 that replaced it, so you can see why customers continued to chase them even after the new model was released. The 6 speed box made the Super Six a more usable two-stroke and the power delivery was smooth. It was a more frantic ride than its four-stroke competitors, but for the rider prepared to dance on the gear-shift while exploring the full rev range it was an exciting ride. Today it is still remembered along with the T500 Titan and lesser known T350 Rebel as one of the motorcycles that cemented Suzuki’s place as one of the big four Japanese companies that would change the industry forever.

Suzuki GT380, GT550, GT750,

After the T series Suzuki, a new war began. Bigger capacity bikes and more cylinders became the norm. To compete, Suzuki released an all new range of two-stroke triples. The smallest was the GT380 and the biggest was the now fabled water buffalo, the water cooled GT750. The GT550 sat in between, and all of them had a certain charm. The 750 was the biggest of all the two stroke motorcycles of its day weighing 230Kg or just over 500lbs. It was built as much more of a touring bike than its Kawasaki competition. The water cooled engine made it a quieter motorcycle to ride too, so it was a better bike for long distance travel than the Kawasaki H2. Handling was always going to be compromised on such a big motorcycle and although not as nervous as the early H2, it could quickly get you into trouble if you weren’t careful. The suspension was soft and what started as a wallow could quickly end up feeling like the frame was made of dough. Not the best situation when you have a screaming 70Hp two-stroke triple between your legs.

Moving down in capacity I will be clear and say, I only rode a GT550 once, so I cant make too many comments, but it did produce a healthy 50 to 55HP and was comparable in performance to the increasing number of middleweight four-strokes on the market at the time. However, sales wise, that just wasn’t enough. It just wasn’t as popular as the earlier T500 Titan and after just 4 years it was discontinued.

The 380 is the one that I would probably put in my garage first. Although not as light and sporty as the Yamaha RD400, it was a comfortable bike with more room for a passenger. The engine was a solid lump that produced around 40HP and as with all the triples, they still have a cult following today. Simple to maintain compared to the four-strokes and enjoyable to ride all day long, they were a great balance between performance and comfort in a practical and well built package.

The GT range as a whole left an indelible mark on motorcycle history and continued to build on the legacy the T series had laid the foundations for at Suzuki.

Next we have a motorcycle that epitomises the statement that bigger isn’t always better.

Yamaha RD350

Looking back now, Yamaha were late to the game with the RD350. The Suzuki T350 Rebel had been released 2 years earlier in 1970, but the first generation Yamaha RD350 arrived with a bang at the end of 1972. It was an affordable, powerful, reliable, high-revving two-stroke twin, producing almost 40HP and over 30Nm of torque at around 7,000rpm. Weighing just 155Kg or 340lbs, the nimble RD350 offered fast acceleration from its “Race Developed” engine and it had precise handling compared to the rest of the market. Its success meant that Yamaha went on to produce the larger RD400 and then the water cooled RD LC range including the now equally fabled RD500LC, which I will talk about later. To this day, the original air cooled RD350 remains an iconic motorcycle that shook up the industry and gave real world performance to the masses.

Next, we leave the road behind for a while as we enter the territory of the big bore two-stroke dirt bikes.

Kawasaki KX500

In 1978 the rumours started about an all new Kawasaki motocross bike built to challenge for the open class title. In 1979 we started to see what the bike could do. Although Brad Lackey won more single races than anyone else on the new Kawasaki, they failed to take the title, but a monster was in the making. After 3 more years of development, in 1983, Kawasaki unleashed the fire-breathing KX500 motocross bike. The press described it as “violent” and “unrideable”. With a 500cc two-stroke single producing around 65HP. It was considered to be at the absolute limit of usable power off road, and it stayed in production for over 20 years, from 1983 to 2004. It became the benchmark by which all other big bore dirt bikes were judged. The KX500 was an immensely powerful bike and weighing in at just 105Kg or 230lbs, it had an incredible power to weight ratio. Unlike the TM400 Suzuki we featured in the “Dangerous Motorcycles” video linked at the end, The strength was there with the Kawasaki as well as the power. Part of the weight loss regime had been the implementation of the race developed Uni-Track rear suspension, but it seemed like every engineering decision had been carefully considered to save weight and increase power. King of the big bore dirt bikes, the KX500 dominated motocross for over a decade, and still retains its unrivalled reputation to this day.

Honda CR250 Red Rocket

Ten years before the KX500 landed, came another motorcycle that missed out in the “Ton Up 250cc Motorcycles” video linked above. The Honda CR250, then called the Elsinore, was first launched in 1973, but it was in 1975 that it went into full blown production and the “Red Rocket” was born. The 250cc two-stroke single was nimble, fast, easy to ride and had bombproof reliability compared to any of its competition. Producing over 35HP standard and weighing just 100Kg or 224lbs it set new standards of both performance and reliability. It dominated Motocross for the next five years and only went out of production in 1983. It earned itself the sort of legendary status few bikes have ever achieved and its increasing rarity can make what was once an affordable motorcycle beyond the reach financially of many, but they will always be remembered as one of the giants of the motocross world.

Yamaha RD500LC

Next we have a very special motorcycle that I mentioned earlier. The Yamaha’s RD500LC arrived in 1984 as the road-going version of Yamaha’s Grand Prix race bike, the YZR500. This is a motorcycle that will always be associated with one man. Not a designer, but a rider. A naturally talented racer of the highest degree. That man was Kenny Roberts. By the time the RD500LC was released he had won 3 world titles and achieved a fame and notoriety that rivalled even the great Valentino Rossi and Giacomo Agostini. With a 500cc liquid-cooled V4 two-stroke engine at its heart, the RD500LC produced over 90HP and was one of the fastest production motorcycles of its day. Weighing just 180Kg or 435lbs it had a phenomenal power to weight ratio. Compared to the slightly more powerful Honda 1100 Magna, released the same year, that 60Kg or 110lbs weight difference made all the difference when it came to speed, although let us be fair, the sleek bodywork probably helped when comparing it to bikes like the Magna. Equal parts terrifying and exciting, the RD500LC was the ultimate road going adrenaline rush and it was the pinnacle of the now fabled RD range of motorcycles. In a world of ever more powerful race bred motorcycles, they weren’t always the fastest, but they were a consistently better all round package than any other race replica motorcycle that had ever been produced at the time in my humble opinion.

Yamaha YZ490

Also, in May of 1984, Yamaha unveiled the YZ490. It was the evolution of 8 years of work developing the previous YZ400. The 487cc two-stroke single made around 55 HP, so it didn’t make quite as much power as the KX500, but it was still renowned as a motorcycle that took no prisoners. Arm stretching torque and sharp geometry made it a handful for all but the best riders, but when in the hands of a good rider, it could devastate the opposition. At 105Kg or 238lbs the YZ490 would clear jumps others wouldn’t dare to attempt, and its success paved the way for Yamaha’s future in the world of Motocross.

Something here that I do find quite interesting and a little amusing. We grew up with these bikes, and at the time they were honestly, too much for most riders to handle, yet now, when we are older and less fit, somehow we are drawn to them, yes, experience can help, but mastering a full blooded two-stroke, big bore, dirt bike, like the YZ490 and KX500 is no easier now than it was when I was young that is for sure. One advantage we do have, is a long lists of more modern parts and upgrades to help improve on the originals and that does help, but don’t be fooled into thinking these bikes became easier to ride somehow in the intervening years. They are still a handful, and getting the most out of them is quite honestly beyond the skill levels of the average rider.

Now, we start to enter less familiar territory. And some of these bikes are the ones you highlighted that I had missed in various other videos.

Bultaco Metralla

Back in the 1970s, racing motorcycles were very different. What you would see on the track outside of the Grand Prix circuits was usually powered by a 250cc two-stroke single or big old 500 four-stroke singles. There were exceptions like the MV, Gilera and others, but they weren’t common. The two-strokes were light and agile, and faster than you might think.

Formed by one of the founders of Montessa, by the late 1960s, Bultaco had built a reputation for off-road motorcycles. The Spanish manufacturer had developed a good network of small shops in the U.S., but they catered mainly to racing enthusiasts, and their dirt bikes sold well. However, their road bikes were built mainly for the home market, so many of these bikes never really got a chance.

Spain built a lot of motorcycles in the 1950’s, but by the late 1960’s the government had put restrictions in place that meant any manufacturer could only build one engine design in various capacity options. Knowing they could only build one engine meant Bultaco were forced to put all their eggs in one basket, and the result was truly astounding.

The Bultaco Metralla used a 32HP, 250cc version of their two-stroke engine and the entire motorcycle weighed just 113Kg or 250lbs. Now bear in mind that most cars from that era didn’t put out 32HP, and most of the motorcycles that did weighed a lot more. At that time, 100 MPH was the target for all fast production motorcycles, and the Metralla could just about get there straight out of the crate. For a time, the Bultaco Metralla was recognised as the fastest two-stroke street bike in the world.

One magazine at the time described riding the Metralla as like “throwing a smoke bomb into a hornets nest, then climbing on”. The skinny tyres and less than prolific brakes must have made for a very exciting, if at times unnerving ride.

Bridgestone GTR350

Next, and released around the same time, was the Bridgestone’s GTR350. It made its debut in 1968 with an all new 350cc two-stroke, parallel-twin engine. The engine broke new ground. It was one of the biggest capacity two-strokes of the time to use rotary disc valve induction instead of straightforward piston port fuelling. This allowed non symmetrical inlet port timing and space for a rear scavenging port. This improved both power and efficiency. The disadvantages were a higher manufacturing cost and a wider motor, but it was a major leap in two-stroke performance. Unlike the competition, the Bridgestone disc valve was built entirely from plastic, which solved the delamination issues that had caused problems for many other manufacturers when trying to introduce disc valves in higher performance engines. The GTR350 weighed around 160Kg or 350lbs so it wast the lightest, but that 350cc engine produced about 40 HP around 5 years before the RD350 mentioned earlier rolled onto the market. With a faster ¼ mile time than most motorcycles twice its size, the Bridgestone would set a new performance benchmark for the other Japanese companies to aim for.

This is another one of those motorcycles where the more I dig the more interesting it gets. It even has its very own conspiracy theory baked into its history, but that is a story for another day. As well as the disc valves, the Bridgestone GTR350 came equipped with other exciting technology. Instead of the usual cast iron barrels or aluminium barrels fitted with iron liners, Bridgestone developed a cylinder coating by literally atomising Chrome wire in a controlled explosion inside the barrels. This coated the cylinder wall with an even layer of far harder and more reliable coating. They also used a dry, air cooled clutch, similar to the one developed for the AJS Porcupine and which later became synonymous with the Ducati name. Bridgestone were so confident in the build quality of these fantastic motors that they were supplied complete with a factory produced manual showing the owners how to extract more power. Many were highly tuned and used successfully in competition, where they became renowned for their reliability as well as their performance and excellent handling.

Kawasaki A7 Avenger

Even earlier, in 1967, a year after the A1 Samurai was unveiled, Kawasaki released the A7 Avenger. One of Japan’s earliest 350cc street bikes. This simple and reliable two-stroke, disc valve, parallel twin, was fast enough to get the designers of every other Japanese manufacturer looking for answers. The engine was identical to the A1 Samurai in every way except for the oversize barrels, pistons and head that gave it the extra capacity. Unlike most two strokes of its time, as well as the oil that was fed in with the fuel, additional oil was injected directly on to the main bearings at the crank journals. In another breakthrough, in 1969 it became one of the first motorcycles to do away with points and use a Capacitor Discharge based ignition system, an innovation we have all appreciated over the years I am sure. Although it wasn’t as simple as adding the extra cylinder like they might have hoped, the A7 Avenger engine was vital to Kawasaki when designing the 500cc triple engine for the first H1, which I featured in the Fast and Furious 500cc bikes video linked above.

As an addition here I have a question. Disc valves had been used on smaller engines before, but Kawasaki and Bridgestone managed to bring this technology to market first in the larger capacity sector, despite the fact that Suzuki had stolen similar plans from MZ several years earlier. Why were Suzuki so late to the party? Answers below in the comments please if any of you have any insight.

Gilera NGR250

Now to finish today’s list we have something both exotic and unusual. The Gilera NGR 250 was only made for two years, from 1984 to 1985. By then the world had be drowned in full bore race replica multi cylinder bikes that were literally race bikes with lights. The Gilera wasn’t, but it was a fantastic little bike. Built around a lightweight trellis frame with bodywork that made it look like a miniature GPZ, the NGR250 is a very rare sight on today’s roads. It used a 250cc liquid-cooled single cylinder engine which produced around 40HP at 7500rpm and 30Nm of torque at around the same point. Weighing just 138kg or just over 300lbs it was a lightweight sports bike with razor sharp steering, but the package was less frantic and not as highly strung as the new Japanese race replicas. This was like an all new version of the Bultaco Metralla, but filled with 1980’s Italian style and a big heap of passion. Compared to the new Japanese two strokes, it was easy to ride and had great pull from low revs for a two-stroke, but it came at a time when the popularity of both two-strokes and 250cc motorcycles in general was on the wane. The changes to licencing laws in the UK and many other countries meant that 250cc bikes were no longer the choice of new riders. This was an era when the 125cc engines would take over in the starter bikes of learners, and the sales of 250cc bikes just kept falling. This left the Gilera, and many other motorcycles in a strange limbo. A sector of the industry that became niche, and little more than a source for production based race bikes. The build quality of the Gilera was undeniable, and the 5 gallon tank, twin front discs and fully adjustable Marzocchi suspension made it a practical, smooth and comfortable ride that was as simple to maintain as it was to ride.

Final Thoughts

It did mark the end of an era in many ways. The beginning of the end for the simple but powerful two-stroke single. A few high performance multi-cylinder two-stroke bikes continued for a short while, but as racing and Motocross moved to four-strokes, the writing was sadly on the wall for the humble strokers.

Well I guess with that we end on a sadder note today, but I hope you enjoyed this journey through the hinterlands of two-stroke history. I hope you had at least a surprise or two and hopefully, like me, you learned a little bit too.

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