It’s not difficult to imagine the old British government officials – pipe in one hand, cup of tea in the other – deciding that motorcycles were getting too fast for public safety. Worse still, the "deciders" had another concern to ponder: young riders with an ‘L plate’ (an addition plate that signified a learner rider) were riding as fast as their motorcycles would go! The obvious solution, to the old officials, was to limit the cubic capacity of motorcycles that learners could use.

And so, in 1960, the biggest engine a learner motorcyclist could have was a 250-cc powered machine.

At the time, this made sense because the 250s available were primarily intended for commuting or touring, and machines such as the Ariel Arrow or Norton Jubilee did not do much for the image of the Rockers of the time. Then everything changed when Yamaha introduced their YDS range. Affordable, fast 2-stokes were available to the masses of ‘L plate’ buyers. And for those wanting even more speed, Ducati offered the first 250-cc motorcycle that was rumored (a regular sales gimmick, often not based on hard data) to be capable of 100 mph. The era of ever faster, sportier 250s had arrived.

The quest for a genuine 250 street bike with a top speed of at least 100 mph by a Japanese manufacturer was a major challenge for the three main suppliers: Kawasaki, Suzuki and Yamaha (Honda stayed true to their 4-stroke preference in the 250 class for a long time). To get the horsepower high revs were essential which created two problems, heat and mechanical reliability.

The first company to overcome these two problems would most likely be the first to offer a 100-mph 2-stroke.

Kawasaki

With a reputation for making fast 2-stroke triples, Kawasaki introduced their 250 1972 with the model designation of S1. Many people thought the prize of having the first Japanese 100 mph 250 2-stroke would be Kawasaki’s with this new model, but the bottom line was that - although the S1 and later KH range (1976 to 1981) sounded great and looked good, they lacked performance in all areas.

With a dry weight of 341 lb.’s (155 kg), and a power output of 30hp, the Kawasaki was expected to easily top 100 mph. Unfortunately, most testers of the time could only get the smoke billowing triples up to 95 mph.

Suzuki

For Suzuki, the turning point in their quest for speed from the venerable 2-stoke came when German Ernst Degner defected in 1961 and joined the Japanese company. Within a year they had won a TT and the world title for 50-cc machines.

The company’s first sporty 250 was known as the T20 (Hustler in the US and Super Six in the UK). The company claimed it was the fastest production 250 available at the time. It had a claimed top speed of more than 90 mph which, for a 250, was a remarkable speed at the time.

X7

From the Hustler onward, Suzuki improved their base machine until the famous X7 came along in 1978 and took the 250 market by storm. The lightweight (321 lb.’s or 146 kg) 28.5hp machine was designed to produce the magic 100 mph top speed. Unfortunately, most testers at the time found the bike’s top speed to be slightly shy of this figure. Nonetheless, the X7 was a very popular machine, until the Yamaha LC came along that is.

Yamaha

The Yamaha motor company had built their reputation on sporting machines in the 60s. In international racing they had become the dominant force in the 250 and 350-cc classes with their TZ racers so it was natural for the company to build on their experience. Producing a fast street 250 for Yamaha was, therefore, a simple case of transferring some of the technology from the race bikes to the street bikes.

The range of parallel twin 2-strokes began with the YD-1 in 1957 and continued up until the emission laws in most countries forced Yamaha to manufacture mostly 4-stroke machines.

The mainstay of Yamaha’s 250 range in the 70s was the RD. These 2-stroke twins were introduced in 1972 and were market leaders until Suzuki brought out the X7.  Although the RD250 had a top speed of around 90 mph only, it had a  loyal following which easily moved to the next evolution of the company’s 250 2-strokes when the LC250 came onto the market.

LC Yamaha, finally a 100 mph Japanese 250

Having proven that liquid cooling on their Grand Prix machines was the way to go for power and reliability, Yamaha finally introduced it on their street high performance machines with the LC (for liquid cooled). In addition to the power gains, the liquid cooling also had the advantage of reducing the noise outputs from the cylinders (something that was becoming important on street bikes).

With 35hp available from the 247-cc 2-stroke engine and a lightweight frame and cycle parts, the LC finally could claim to be a true 100 mph 250. For the learner market in the UK, the LC250 was the bike to have, much to the consternation of the rule makers who soon realized that cubic capacity restrictions had not slowed learners down sufficiently. However, in keeping with the easy way out for the law makers, the British government reduced the engine capacity again in 1983 for learners to 125-cc which quickly decimated the 250 2-stroke market.