Yamaha introduced the RD350 in 1973 and admittedly didn't built it for very long before stopping production in 1975. Consumers considered the RD350 to be a racing bike – and even believed RD stood for Racing Developed with no particular proof besides the fact that it sported a powerful engine. The RD350 was indeed known for being a fast bike due to advancements in both its engine and transmission. We know a bit about the Yamaha RD350 and have more information about why it was made – and why Yamaha stopped making it.
Development and History
Yamaha started working in the Japanese racing scene in the 1950s with a 125cc YA model motorcycle, and did well enough to keep going and expand to more races with different motorcycles, including a RD56. An importer from Canada actually modified a 250cc Yamaha to make one of the first available 350cc, a model of which finished second at the 1968 Daytona 200.
The street racing bike had become more viable, more well known, and in many ways, more desirable. With more and more well paved American roads available, drivers now had the ability to find a fun stretch of road to drive on, and at any given hour of the day, have the opportunity to open the throttle on an RD350 without too much danger of traffic. Motorcycle magazines loved it – and believed it was a race motorcycle that looked like a city street motorcycle.
Given the loud, throaty pipes of this “street machine” and its the propensity to use some gas, Yamaha stopped selling it in the US as emissions standards became a concern – as well as laws about the sound coming from vehicles. Rather than modifying the fun out of the RD350, they looked to the future.
The biggest change between a 250cc from Yamaha and this 350 was a charge in port design. They moved the reed valves into the intake. This allowed better port timing which gave the RD350 more acceleration, a bigger powerband, and higher RPMs.
Some found the engine a little unusual. It often needed to have the choke on full to start up – and would need a minute to heat up before really going at it.
The engine was mostly notable for being fast – as it was a capable street racing machine. The very powerful two stroke engine that made the RD350 so famous also meant the end of it due to EPA regulations.
It was indeed fast – capable of going a bit over 100 miles per hour, and a fast for the time 0-60 in about 6 seconds.
One other feature of the Yamaha RD350 was Autolube system which had a tank holding a half gallon of oil – rather than dumping some oil in whenever you stopped at the pump.
A couple of the most unique features of the Yamaha RD350 were a front disc brake and a six speed transmission. The front disc was deemed necessary because of the RD350's ability to go fast. This also meant that some inexperienced riders would knock themselves off balance by braking too strong – and thinking that their front brake was a less powerful drum brake. A pair of cylinders drove the front brake – and gave it quite a grab. On the plus side, the bike stopped well!
Six-speeds gave the driver opportunity to go faster and keep reasonably low RPMs throughout the RD350s powerband. It was also one of the savers of fuel economy on this beast.
Most drivers considered the suspension to be soft, but nimble. The RD350 was a very fun bike to take on a winding road.
Impact on Motorcycle Culture
American motorcycle customers generally had one demand: make it more powerful. Giving what appeared to be a regular street bike a much more powerful 2 stroke engine gave American customers what they wanted, even if Yamaha knew they couldn't keep making it for long to due emissions issues. The RD350 is still a legend in many countries, including India, today.
The bike felt the love stateside, where magazines and drivers alike loved it's relatively soft ride – and unexpected straightaway speed. It also helped that the bike was very good at getting attention with it's loud pipes.
At the same time, it was not particularly safe, especially for newer drivers. Some jokingly said that “RD” stands for Rapid Death – as both the powerful of the engine compared to the conservative look overwhelmed some drivers – add on that powerful front disc brake and you had a recipe for throwing someone head first over the handlebars. Unfortunately, it also had worst gas mileage than most cars at the same, thanks to the 2 stroke engine – but boy was it fun!