The Yamaha RD350 motorcycle was the “poor boy racer” of the 70s because it was fast and relatively affordable. In this article, I’ll describe the Yamaha RD350 bike, including its key specs and features.
During its heyday, the Yamaha RD350 ruled the motorcycle race tracks. It was faster than many bikes that cost much more. At the time, The RD350 cost about $900, whereas comparable bikes cost up to $3,000. This is why it became known as the racing bike of the poor.
The Yamaha RD350 is a sportbike that is powered by a 2-stroke gasoline engine. Yamaha Corporation started making this fast and powerful motorcycle in 1973. The five-speed Yamaha 350 cc R5 inspired its overall design. Yamaha ended the production of this motorcycle in 1975.
Read on to learn more about the Yamaha RD350, including its full specs and features.
Yamaha RD350 Specs and Review
The Yamaha RD350 can be considered an innovation in motorcycle design and production. When big and muscular motorbikes ruled motorbike racing, Yamaha introduced a smaller but faster machine, the Yamaha RD350. Despite its smaller size, it outperformed its bigger competitors at the race tracks.
Selling only for $908 at that time, the Yamaha RD350 beat other more expensive bikes made by other reputable brands that cost from $2,000 to $3,000. That feat earned the Yamaha RD350 the moniker ‘racing bike of the poor.’ In effect, this bike opened the doors for the masses to participate in motorbike racing.
The Yamaha RD350 is classified as a sportbike. It went into production in 1973, and the last unit that exited its factory was in 1975. A 2-stroke gasoline engine powers this racing machine. The 5-speed Yamaha 350 cc R5 directly inspired its design.
Yamaha RD350 Essential Specs
The Yamaha RD350 is equipped with a two-stroke, air-cooled, reed valve-equipped intake tract, parallel-twin, six-speed gasoline engine. Yamaha classified this motorbike as a sportbike. All variants of the RD350 came with an ‘Autolube’ automatic oil injection. This saves time because you don’t have to mix gasoline with two-stroke oil yourself. The machine does it automatically.
There are two rim sizes available at that time. One is the 18” x 1.85” WM2 for the front, and the other is the 18” x 2.15” WM3. Both rims are chrome finished, with wire-spoke steel construction. The bike is equipped with a single front disc brake and a single rear drum brake. This combination is the best in its class, according to Cycle Magazine.
The 347 cc stock engine of Yamaha RD350 produced 39 horsepower (29 kW) at its rear wheel at 7,500 revolutions per minute. At that time, this is truly fast for its bike size. Its nearest rival in the 1970s was the Kawasaki H2. Its 750 cc engine generated 74 hp.
During its production period, the RD350 evolved into a more refined and cleaner engine. In 1976, the engine was called RD400C, and the Yamaha ‘D’ and ‘E’ from 1977 to 1978. The final model was named white 1979 RD400F.
Yamaha RD350 Full Specs
The table below will give you the full specifications of the Yamaha RD350:
|Engine Type||2-stroke, Twin Cylinder (Parallel), Air-cooled, Torque Induction with Twin Carburator|
|Minimum/Maximum Power||30.5 BHP @ 6750 rpm (India), 39 BHP @ 7500 rpm (Japan)|
|Minimum/Maximum Torque||32.3 NM @ 6500 rpm (India), 37.2 NM @ 7000 rpm (Japan)|
|Starting System||Kick starting|
|Ignition||Battery, dual coils, breaker points|
|Induction System||2, Mikuni VM28 SC|
|Air Filter Type||Disposable dry paper|
|Wheels and Tires|
|Front Tire Size||3.00 x 18″ – 4PR|
|Rear Tire Size||3.50 x 18″ – 4PR|
|Front Brake||180mm Drum (India), Single 267mm disc 2 piston caliper (Japan)|
|Rear Brake||180mm Drum (India), 180mm Drum (Japan)|
|Mileage and Performance|
|Top Speed||150 to 170 kph|
|0-100 kilometers per hour||7 seconds|
|0-150 kph.||16 seconds|
|Fuel Tank Capacity||16 liters|
|Oil Capacity||2 liters|
|Electricals and Transmission|
|Chassis and Suspension|
|Overall Length||6.7 feet (2040 mm)|
|Overall Width||2.74 ft. (835 mm)|
|Overall Height||3.64 ft. (1110 mm)|
|Seat Height||2.63 ft. (800 mm)|
|Wheel Base||4.33 ft. (1320 mm)|
|Ground Clearance||0.50 ft. (155mm)|
|Handlebar Width||3.25 ft. (990 mm)|
|Turning Circle||7.55 ft. (2300 mm)|
|Dry Weight||314 pounds (143 kilos)|
|Bike Colors||Black, Silver, Red, and other colors|
See the below video for a great Yamaha RD350 review, including a test drive and rundown of its key features:
Yamaha RD350 Features
This motorbike has a lot of things going for it in its time. Yamaha Corporation has many positive things that it said about this machine. But how does it perform? If you are thinking of buying a used RD350, consider the following features:
1. Light and Easy
Unlike other bulkier and heavier bikes of the early 70s, the Yamaha RD350 was light and easy to maneuver. This is just what aspiring racers want so that they will be able to master their skills in cornering. In the words of a bike racer, “it was fast, wheelie prone and brutal.” This quality is perhaps the reason why new-gen bikers gave the RD350 a new name: Racing Death.
2. Comfortable Ride
By today’s standards, this motorbike is tiny. But with its decent flat bars combined with a perfectly matched seat, even if you are six feet tall, you will have a comfortable ride while traveling for hundreds of miles between fuel stops.
This little motorcycle can corner on rails, although it wallows and grinds its low-slung undercarriage at mild, lean angles. It can achieve 60 miles per hour (mph) in just about 4 seconds. The stock mufflers are tastefully muted, so the exhaust note sounds like heaven.
3. Able to Carve Corners Fast
The Yamaha RD350 was created in the days when fuel is still relatively cheap. It was minimally designed to efficiently eat up twisty pavement instead of negotiating boring long and straight stretches.
The engine and the frame of the RD350 are the things that enabled it to carve corners quite fast. Their design was inspired by the 750 hp powered Yamaha TR2’s structural and engine design.
Although the RD350s frame has a thicker wall tubing, its geometry is about the same as the TR2. It has a longer transmission and a dry clutch, but its crankshaft and engine case are almost identical to the liquid-cooled 1973 TZ350.
4. Major Engine Upgrades
The Yamaha RD350’s development started when their engineers updated the Yamaha YR1 models and improved its styling in good measure. These were air-cooled, two-stroke, and parallel-twin motorbikes. Eventually, they came up with the R5 engine that can produce 35 hp.
Reed Valve Induction
Its 347 cc engine borrowed most of its basic design from the engines of production racers. That included the two-stroke engine and the double-cradle frame. It exhibited major engine upgrades over previous Yamaha engines. One of the engine upgrades is the reed valve induction.
Reed valves are inserted into the intake tract of the RD350 2-stroke engine. This setup allows gas and air to flow into the engine only one way. Standard two-stroke engines compress the air and fuel mixture in the crankcase. In this simple piston-to-port engine, the air/fuel mixture can leak back into the carburetors. This is called ‘blow-back.’
With reed valves inserted into the engine intake, this will no longer happen. There is only one way out, so the fuel and air mixture can’t back out. This improves the cylinder filling in the engine’s combustion cycle.
Additional Port in the Induction System
There is also an additional port in the induction system of the RD350 engines. When a piston of the RD350 is near the bottom of its stroke, it uncovers a small port directly from the carburetor manifold.
An extra shot of the air/fuel mix is inducted when preheated compressed air or fuel mix enters the combustion chamber (coming from the crankcase). Yamaha claims that this will improve the combustion chamber’s filling, improved scavenging, and cooled the piston crown.
5. Powerful Engine
Yamaha claims that the reason why the RD350 engine can pull well from 4,500 to 6,500 RPM is due to the combination of the following technical design upgrades:
- Torque Induction system
- Crankshaft that is supported by big ball bearings
- Roller bearings at the bottom and needle bearings at the top of the connecting rod
- 6-speed transmission
This engine, according to Yamaha, can produce 39 hp and reach a top speed of almost 100 mph because of these engine upgrades. Aside from these, the engine’s reed valve system improved fuel efficiency, a perennial problem for two-stroke engines in the 70s. Road tests proved that this engine could achieve a fuel efficiency of 35 to 40 mpg.
When rounding a curve, it should be systematically transmitted to the ground for power to be used effectively. The Yamaha RD350 has a stiff frame with added bracing. There are also gussets around the steering head and the swingarm. Road testers of this bike were impressed with its stability and ability to change course while turning.
A rider should easily control his motorcycle’s power. In this respect, road testers found out that the front brake of the Yamaha RD350 is one of the best. This motorbike has a master cylinder that operates two 1.75-inch brake pucks installed on a 10.5-inch disc.
Cycle Magazine approved this setup and said that the RD350 could produce a strong enough decelerative force to push your eyeballs out. From 60 mph, it took the RD350 122 feet to stop.
While this cannot beat today’s standards, in 1973, it was not common to abruptly stop speeding motorcycles this way. The brakes of the Yamaha RD350 are very responsive, even if given light pressure.
Quick and Easy Gearshift
The 2-stroke engine of the RD350 needs to be revved if you want it to perform. But you will find that gearshifts are easy and fast. It will not make you feel that shifting is a chore.
In the 70s, the Yamaha RD350 has built a reputation as a low-maintenance motorcycle. Some RD350 owners testify that they need to do very little to their bikes. One bike racer even said that they never had an injector fail.
But to have their machine running without any problems, they make it a point to have their bikes checked by a qualified mechanic every 3,500 miles. The usual checks done are on the carbs, the contact points, and the condenser. Spark plug replacement is also done regularly.
End of Production of the Yamaha RD350
In the mid-70s, the Yamaha RD350 was the official motorbike of the working class. Ed Burke, a Yamaha product planner, stated that it “was a cult bike if there ever was one.” It was cheap, but it can fight toe to toe with other bigger bikes and come out the winner.
But more sophisticated bikes were created over the years, with faster four-stroke engines. Customer tastes and preferences changed, and riders wanted bigger and faster bikes. Added to that, the EPA also wanted them to be cleaner.
Eventually, Yamaha turned over its production of the RD350 to the RD400 in 1976. No more RD350s were produced from then on. The RD400 suffered the same fate as well. It began disappearing in Yamaha’s dealer showrooms at the end of 1980.
Some used Yamaha ED350s that you can buy, although you have to really search for them. If you find a good one at a good price, grab it, for it is a really capable and mean machine.
Conclusion: Yamaha RD-350 / RD350 Review
The Yamaha RD350 is a sportbike that ruled the motorcycle race tracks during its heyday. Yamaha Corporation produced it at a time when race bikes are heavy and muscular. Due to its lighter design, this motorbike, although costing only around $908, beat motorbikes of other popular brands with price tags ranging from $2,000 to $3,000.
This feat earned this motorbike the name ‘poor man’s racing bike.’ A 2-stroke gasoline engine powers the Yamaha RD350. It started production in 1973 and ceased production in 1975. Lastly, Yamaha based its overall design on the Yamaha 350 cc R5.