Yamaha YR-3C
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| Yamaha YR-3C | |
| Manufacturer | |
|---|---|
| Production | 1969-70 |
| Engine | Two stroke, parallel twin |
| Compression ratio | 7.5:1 |
| Transmission | 5 Speed |
| Brakes | Front: Drum Rear: Drum |
| Front Tire | 3.00-18 |
| Rear Tire | 3.50-18 |
| Wheelbase | 1340 mm / 52.7 in |
| Weight | |
| Recommended Oil | Yamalube 10w-40 |
| Fuel Capacity | 15 Liters / 4.0 gal |
| Manuals | Service Manual |
Engine[edit | edit source]
The engine was a Air cooled cooled Two stroke, parallel twin. The engine featured a 7.5:1 compression ratio.
Chassis[edit | edit source]
It came with a 3.00-18 front tire and a 3.50-18 rear tire. Stopping was achieved via Drum in the front and a Drum in the rear. The front suspension was a while the rear was equipped with a . The YR-3C was fitted with a 15 Liters / 4.0 gal fuel tank. The wheelbase was 1340 mm / 52.7 in long.
Photos[edit | edit source]
Overview[edit | edit source]
Yamaha YR3C
In 1967 Yamaha introduced a new model to their production line, known at the
YR-1 Grand Prix. This motorcycle was the largest in the line that year, and
represented a lot of firsts for Yamaha. It was the first 350cc motorcycle they
had built. The engine was the first to use aluminum cylinders with cast iron
sleeves, rather than all cast iron cylinders. It was the first to make use of
horizontally split crank case, which made major engine work much easier.
The engine was a twin cylinder, piston port, two stroke, five speed,
producing 36 horsepower, which at the time, was a big deal. The engine was a
three port configuration, and the cylinder heads were machined to allow for
squish of the compressed fuel mixture, allowing for a more complete burn.
Another first was that the clutch was mounted on the transmission input shaft,
rather than directly to the crank shaft. The advantages were that the input
shaft rotates at much lower speed than the crank, there by making the clutch
much more smooth in operation, and increasing the life of a clutch tenfold. It
also had oil injection when many of its competition were still mixing gasoline
with oil.
An innovative feature of the YR-1 engine was that the shift shaft and lever
could be set up on either side of the engine. In Europe, motorcycles shifted on
the right side, while in Japan and North America, the left. Likewise, the rear
brake petal could also be changed to accommodate left or right side braking.
This motorcycle, to put it bluntly, was a road racing engine and chassis,
with enough lights and instrumentation added, to make it street legal. When
taken to the drag strip it absolutely smoked 650cc triumph's, and pretty much
everything else.
It was produced in three colors, candy red, candy blue, and gloss black,
being the rarest of the three. It was also given a lot of chrome such as both
fenders, chain guard, handlebars, side panels of the fuel tank, gas cap, head
light bezel, and so on. The front brakes were of the twin leading shoe variety,
offering plenty of stopping power.
In short, this motorcycle was revolutionary in its day, and is a fairly rare
classic today. The fact is, and it's no secret, that Yamaha borrowed the name of
it's first road rocket for one of its newer machines, the yzf-r1.
This one machine set the stage for the future in the 350cc class. With never ending innovation taken from racing and applied to production, the YR-1 was the first in a long line of racebred motorcycles that followed. These were the YR-2 (1968), YR-3(1969), R-5(1970), R5-B(1971), R5_C(1972), RD-350 (1973-76), RD-400(1977-80), RD-350 LC(liquid cooled), and finally the RZ-350. The engine from the lc version lives today in the Yamaha Banshee ATV. Source
| Make Model | Yamaha YR3C |
|---|---|
| Year | 1969-70 |
| Engine Type | Two stroke, parallel twin |
| Displacement | 347 cc / |
| Bore X Stroke | 61 х 59.6 mm |
| Compression | 7.5:1 |
| Cooling System | Air cooled |
| Induction | Carburetor |
| Ignition | |
| Starting | Kick |
| Max Power | 36.5 PS @ 7500 rpm |
| Max Torque | 3.3 kg-m / 23.9 ft-lb @ 7000 rpm |
| Transmission | 5 Speed |
| Final Drive | Chain |
| Front Suspension | |
| Rear Suspension | |
| Front Brakes | Drum |
| Rear Brakes | Drum |
| Front Tire | 3.00-18 |
| Rear Tire | 3.50-18 |
| Dimensions | Length: 2040 mm / 80.3 in Width: 735 mm / 28.9 in Height: 1005 mm / 39.5 in |
| Wheelbase | 1340 mm / 52.7 in |
| Ground Clearance | 145 mm / 5.7 in |
| Weight | 157 kg / 346 lbs |
| Fuel Capacity | 15 Liters / 4.0 gal |