The 90cc, 10.5 HP Battle for the Prestige of Four Manufacturers [Catalogs Reflect the Era: Part 19]

In August 1969, Honda released the CB750FOUR, a high-performance four-cylinder motorcycle that surprised the world. With a maximum output of 67 horsepower, it was by far the top-ranking domestic model and became the object of desire for motorcycle fans.

One month later, Kawasaki released the 500-SS Mach III. Although its maximum output was 60 horsepower, it achieved the same 12.4-second quarter-mile acceleration as the CB750FOUR, marking the beginning of a high-performance competition in large sport bikes.

During that era, a quiet competition for maximum output began in the 90cc class, which could be called the "youth bike" for young people.

※Please note that the catalogs introduced are privately owned, so there may be some dirt.

The Presence of the 90cc Class

In the late 1960s, there were two types of motorcycle licenses: moped (Class 1) and all other engine displacements.

In my experience, the practical skills test for the general motorcycle license, often conducted at police stations, was done on a 125cc motorcycle. Passing this test allowed riders to operate motorcycles of any displacement.

In an era without the "three no's" movement in high schools, obtaining a motorcycle license at 16 was commonplace. Many high school students were seen commuting to school by motorcycle.

For high school students and young people, the 90cc class was an attractive option, both as an object of aspiration and as something financially accessible.

Kawasaki Releases a Model with an Astonishing 10.5 Horsepower

In 1968, Kawasaki released the "90S" and "90SS" with a maximum output of "10.5 PS".

Previous 90cc models had a maximum output in the 8 horsepower range. 10.5 PS was an astonishing performance and became a significant factor when young people chose a motorcycle.

Kawasaki 90-SS (from the 1970 general catalog): Air-cooled 2-stroke, rotary valve, single-cylinder. Maximum output: 10.5 PS/8,000 rpm. Price: 79,000 yen.

*Transmission: 5-speed return for the 90-SS, 4-speed rotary for the 90-S.

Now, let's look at the situation of each manufacturer's 90cc models in 1968.

1968 Yamaha General Catalog: The slogan "Yamaha Responds to Youth" reflects the era.

Excerpt from the 1968 Yamaha General Catalog.

1968 Yamaha AT90.

Yamaha did not have a 90cc road sport model at that time.

The AT90, equipped with Yamaha's only 2-stroke, 2-cylinder engine in the 90cc class, was a sporty business model. The AT90 delivered a maximum output of 8.2 PS/8,000 rpm.

Suzuki offered the 2-stroke, single-cylinder AS90. It produced a maximum output of 8.4 PS/7,500 rpm. Its styling lacked sportiness due to its press backbone frame.

1968 Suzuki AS90.

Suzuki AS90 (from the 1969 general catalog).

Honda offered the Benly CS90, the only model with a four-stroke engine. The CS90 was popular for its good fuel economy and durability, but its maximum output of 8 PS/9,500 rpm did not excite young people.

1968 Honda Benly CS90Z catalog.

Honda Benly CS90Z.

Second Place: Yamaha's HS1

In 1968, Yamaha quickly exhibited the new road sport model HS1 at the Tokyo Motor Show and released it nationwide on December 1st.

The engine was based on the AT90's twin-cylinder engine, with the maximum output increased to 10.5 PS/8,000 rpm. The frame adopted a diamond type, contributing to its agile styling. The high-pitched exhaust note produced by the twin-cylinder engine and dual mufflers was unique.

1968 Yamaha HS1.

14756938001000

Yamaha HS1 from the 1969 Sports Catalog.

Third Place: Suzuki's Wolf 90

In 1969, Suzuki mounted a newly developed 2-stroke, 2-cylinder engine on its uniquely shaped Tri-Form frame, achieving a maximum output of 10.5 PS/8,500 rpm.

Catalog issued in April 1969.

From the 1968 Suzuki Wolf 90 catalog.

The straight handlebar, long front and rear fuel tank, and semi-up muffler created a bold styling reminiscent of racing machines.

Suzuki Wolf 90 specifications. The innovative Wolf 125 was also released simultaneously.

Within a year of Kawasaki achieving 10.5 PS with the 90S and 90SS, the 90cc road sport models from the three manufacturers were all at 10.5 PS.

This made Honda's next move a point of focus. The question was whether Honda, a four-stroke manufacturer, could achieve the same 10.5 PS as the two-stroke engines.

Fourth Place: Honda Achieves it with a Four-Stroke

In January 1970, Honda released the Benly CB90, equipped with a newly designed, upright, four-stroke OHC single-cylinder engine. Achieving a maximum output of 10.5 PS/10,500 rpm, this brought all four manufacturers' 90cc models to 10.5 PS.

While two-stroke engines generally make it easier to achieve higher maximum outputs in small displacement motorcycles, Honda likely challenged this with a four-stroke engine out of pride as a four-stroke manufacturer.

1970 Honda Benly CB90.

Honda Benly CB90 explanation and specifications page, 1970.

The model name "CB" was adopted, befitting a super sport.

At this point, Kawasaki, the veteran of 10.5 PS, expanded its 90cc class lineup to compete with the other three manufacturers.

In 1970, based on the 90-SS, they added the stylish 90-SS Deluxe, featuring a new fuel tank. They highlighted the advantages of the 2-stroke single-cylinder engine, such as the lightest body weight in its class and the only double-cradle frame in its class. The maximum output, of course, was 10.5 PS.

1970 Kawasaki 90-SS Deluxe.

Although a female model is featured, the text "A challenge to men" indicates how few female riders there were at the time.

1970 Kawasaki 90-SS Deluxe explanation & specifications page.

Comparing the specifications of the 90cc road sport models from 1970, we see the following.

Although the engine types are not identical, the maximum output and maximum speed, which are key figures in catalogs, are the same for all four models.

Young people at the time would compare catalogs and read comparison tests in specialized magazines thoroughly for reference. It was lucky if they could borrow a friend's bike, but very few people could actually test ride a bike before purchasing it.

In such an era, catalog figures were very important in making a purchase decision.