Yamaha 350 Grand Prix
YAMAHA 350 GRAND PRIX
CYCLE WORLD ROAD TEST
More Muscle For The Road Rider
THE BIG RACE among Japanese motorcycle manufacturers as to who would have a quality 350cc machine in the U.S. has finally been won by Yamaha. Factory designation is YR1, but to Americans the name Grand Prix will undoubtedly become more meaningful and easy to remember. Obviously Yamaha in its heritage, the Grand Prix reaches a new level in attractive styling. The general appearance is similar to the now popular lOOcc twin introduced last year; in fact, public reaction has encouraged Yamaha to pattern two 1967 machines along these lines.
pattern
The gas tank has a slight decrease in capacity, about one-half gallon less, but what it does for good looks in general makes up for this minor sacrifice. Also, the side panels housing such things as the oil tank, tool box and air cleaner are faired to match the gas tank styling.
These, however, are all sheet metal changes and, while expensive to bring about, do not affect the total motorcycle as much as engine modifications. It is in the engine that the Grand Prix is really different from any Yamahas seen previously. Immediately obvious is the square shape of the new cylinder finning. Closer inspection will reveal a large circular hump on the rear of the primary drive cover. This hump is to allow for a gearbox mounted clutch; something very new for Yamaha.
Previously, Yamaha used an engine speed clutch mounted on the crankshaft that performed well enough — even under the punishment imposed by racing — when fitted to the TD series. There are disadvantages, though, with an engine speed clutch because of the high speed at which the plates are revolving. Most important to the rider is that it has a tendency to grab or snatch when trying to get underway. If the clutch is mounted on the gearbox mainshaft, it is turning at a fraction of engine speed, depending on primary drive ratio. In the case of the YR1, the primary drive ratio is 2.87 to 1, so if the engine is turning 2,000 rpm, the clutch is turning less than 700. At these lower speeds the clutch is much more predictable in operation, and the design engineers are faced with fewer problems dealing with surface speeds and peripheral velocity, so the clutch will have a larger diameter if it is mounted on the gearbox.
In practice, the clutch is much smoother than on previous Yamaha models, particularly when starting away in low gear. On older Yamahas, the rider might have felt that the engine was peaky, which, in fact, was mostly due to the clutch. Now, with better engagement, plus additional displacement, the YR1 is a much more pleasant motorcycle all around.
Understandably, with a new engine, the gearbox internal ratios are quite different from what we are used to on a Yamaha. First gear is sufficiently low for any situation that a touring rider might encounter, even while carrying a passenger. Spacing through the intermediate gears is quite satisfactory, but the gap between fourth and fifth is unusually wide, and if the road is not level, or if it is uphill, it is necessary to take engine revs high in fourth to ensure being up on power in fifth gear after the change. We have noticed this in several Japanese machines tested lately, and the reason is that riders will be using third or fourth gears most of the time, but under favorable conditions, fifth can be used as an overdrive. At most legal highway speeds the engine is loafing along; for instance, 65 mph in fifth gear is less than 5,000 rpm. This means longer engine life, greater fuel economy and, most important, less fatigue on the rider during long periods in the saddle.
Two-strokes usually suffer from a high level of carburetor intake noise, and in the past, Yamahas have been quite bad in this respect. The YR1, however, is almost completely without intake noise. A washable paper air cleaner element is used for filtering and does a very effective job of silencing as well, even under full throttle conditions. The engine did not leak oil during the whole test period and the rear of the machine, which often collects an oil film, particularly with two-strokes, remained completely oil free.
Although the YR1 has conventional Japanese positioning of foot controls, with the gear shift pedal on the left, there is provision for changing to right foot shift without the need of an external crossover system. At present, a plastic plug blanks off a hole in the right-hand side of the gearbox. This is a welcome feature for American riders, particularly those who learned to ride with the shift pedal on the right. For new, inexperienced riders there is still merit in having the brake on the right. The rear brake pedal is unusually short for American size feet, but this is the only thing about the whole machine that is small. In all other respects, the YR1 is a full size motorcycle and will easily accommodate a six-footer with no trouble.
Brakes are adequate, especially the front. Some of our testing was conducted in the nearby mountains and, despite hard downhill usage, we did not detect brake fade. The suspension, both front and rear, is quite firm; this we like. There has been a trend towards ultra soft suspensions on touring machines, but the firmness and steadier handling of a stiffer ride is more important.
The rather massive tubular frame is undoubtedly one of the leading contributors to good handling; all major stress areas, such as steering head and swing-arm mounting, are heavily gusseted. Twin front downtubes extend under the engine and rise rearward to the top of the rear suspension units. The gusseted swing arm is mounted inside the cradle side members. Although standard practice a few years back, sidecar mounts are quite unusual these days. However, the YR1 has a mounting point on the left front downtube. (But being on the left means that it is on the wrong side for sidecar use in the U.S.) The low first gear ratio and new clutch make the YR1 a satisfactory machine for light sidecar duty.
An instrument panel is faired into the headlight housing as on previous Yamahas. It contains a speedometer, rev counter, neutral, discharge and high-beam indicator lights. The lower fork crown has a built-in anti-theft lock. Handlebars are high and comfortable for extended touring, although smaller bars would have increased performance figures slightly. fll
YAMAHA
350cc YR1
$800.00
