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►For a long time the 350
class motorcycles were in a class by themselves. They have been the almost-big
bikes, with more performance and higher cruising speeds than the 250's but
without the effortless acceleration and hill-climbing ability of the big-inchers.
The reason for the creation and perpetualization of this intermediate size is
money: manufacturers found they could offer quite a bit more performance at this
displacement without a great price increase over the 250's. Today, with the
advent of high-priced, sophisticated designs in the large-displacement classes,
the 350 class is flourishing more than ever.
The latest offering from Yamaha in that class is an
indication that, because of considerable attention given this intermediate size,
the middle-displacement bikes are getting closer and closer to the big bikes in
performance. The new RD-350 we tested is capable of cracking through the
1/4-mile timing lights at a pace that would put to shame most 650 four-strokes
being produced today.
The RD 350
not only has great acceleration but outstanding braking as well. With the RD 350
comes a big disc brake at the front that has all the stopping power of the
previous R 5's very good double-leading-shoe brake, with the added benefit of
exceptional controlability and "feel." Throughout our testing the disc hauled
the RD 350 down from high speeds repeatedly without fade. The only flaw in the
new stopper is an audible squeal that occurs mostly at slow speeds of 10 mph or
less.
The RD 350's
stress on performance makes it somewhat of an oddity compared to its
competitors. The other "big three" Japanese manufacturers have filled that
displacement slot with three and four cylinder machines that boast the latest in
comfort and convenience, achieved mainly by the super-smoothness of a
well-balanced multi-cylinder engine. They are acclaimed for their sophistication
and class, but when it comes to accelerating away from a stoplight, pulling out
from a freeway on-ramp or shooting up a steep mountain road, they leave the
rider feeling more than a bit impatient. Yamaha has not gone for the opulence of
a 350 two-stroke multi perhaps because they knew there would be no progress in
terms of performance and that in the end the buyer would have to cough up an
extra few hundred just for knowing he had the latest, most complicated design
the manufacturers could offer. What Yamaha has been offering out on the road
race courses in the form of their super-fast "giant-slayer" 350's they've now
put on the road — a strictly performance machine capable of outrunning most
bikes twice its size.
In design
the RD 350 is a straight-forward two-stroke twin, except for this year's
addition of reed valves. Perhaps they figure what reeds did for their
motocrossers they can do for their street bikes, too. They weren't wrong. The
new RD 350's like the DT-2 reed valve dirt bike, is much faster than its
piston-port counterpart. The name Yamaha slaps on their reed intake systems is
"torque induction," which, I suppose, is to help convey the generally held
notion that compared to the piston porting, reeds give the engine much more
low-rpm power (commonly referred to by super-enthusiasts as "torque"). If the
new reeds on the RD 350 induced any more "torque" than the R5C produced, we
didn't notice it. The RD 350 has a bunch more on the top end but the low end has
remained the same. Mid-range unfortunately has suffered somewhat in the process
and our RD 350 had a definite flat spot between 4,000 and 6,000 rpm. The story
is that you can't get something for nothing. The design of the reed systems
turns out to be much like that of a camshaft. There are high-rpm and low rpm
reeds just like there are high-rpm and low-rpm cams, the effective range of the
reeds being determined by the tension of the reed material. Stiff reeds give you
good valve control at high rpm but are restrictive at the low end, while looser
reeds work easily at low rpm but "float" at the high end. Yamaha's reeds are
evidently on the stiff side; power comes on at 6,000 and gets stronger as the
peak at 8,500 is reached. This might not seem like much of a spread, and it
isn't, but the new super-slick 6-speed gearbox makes the narrow power band much
easier to accept.
The fact
that it's still only a twin combined with the new reed valves helped our RD 350
to get very good gas and oil mileage. You can expect 50 mpg out on the freeway
and seldom will there be much smoke coming from your exhaust. Another
interesting thing about the twin-versus-multi comparison is that because of
Yamaha's short stroke design (64 x 54 mm) and its very high (numerically low)
top gear piston, speeds are actually less than those of its multi-cylinder
counterparts. If that is any indication of potential wear, the RD 350 should
last a long time.
Out on a
twisty road you can really appreciate the RD 350. There's no production machine
we know that will out-handle it, and if you keep the gutsy twin on the boil the
time between corners will be just as impressive as the short time around them.
The handling is marked by great stability at all times, and compared to previous
Yamaha 350's, there is great improvement in handling over the bumps.
Curiously,
the RD 350's very good performance is most obvious when you try not to use it.
There are some who would choose a good 350 for a long-distance mount, but in a
variety of ways the RD 350 lets the scenic cruiser know maintaining an even pace
over a hill and dale isn't its forte. Not until the tach is reading 5(100 rpm
you can be sure that approaching hills and traffic passing situations can be met
just by applying additional throttle. Naturally, a gearbox with so many speeds
invites shifting, and the RD 350's peaky power makes that invitation a
necessity. There are times when you can make a hill by really rapping on the
throttle, if you're cruising at 4,500 rpm or so, but the very loud howl coming
from the intake tract makes you wish you had downshifted. The RD 350's
unwillingness to hold an even pace was most clearly brought home when we were
calibrating the speedometer. Our practice is to hold the machine at a constant
speed indicated by the speedometer and compare the reading with an electronic
device attached to the front wheel. Even on a flat, level surface we had
difficulty holding a constant 60 mph. The engine feels very high-strung and
reflects this by demanding to be turned either on or off. This peaky power band,
coupled with the unwillingness to hold an even speed, is most dramatic when
riding two-up. Hills require at least one down-shift, and sometimes as many as
three if you're just humming along at 35-40 mph. Also, the suspension is
definitely on the stiff side, just right for taking corners over rippled
surfaces, or for taking corners over any surface, for that matter. But it's also
a suspension that the long-distance tourer won't find very comfortable. Those
railroad crossings are especially painful and in most cases the rider resorts to
standing on the pegs over the bumpy tracks. This forced, Joel Robert kind of
riding looks a hit foolish in traffic.
No, we don't
think the best place for the RD 350 is on the turnpike, and if any of the
aforementioned drawbacks don't bother you, the vibration will. Between 4,500 and
6,000 rpm, engine vibration is noticeable but bearable. Above that, it's very
uncomfortable. This translates into a maximum comfortable cruising speed of
about 60 mph in top gear, which is a tad below what the interstate rider would
like. Five years ago, many of us would have described the RD 350 as
"electric-motor smooth," but today, with the silky-smooth competition, we are
forced to reevaluate our standards.
If
performance is your bag, though, the RD-350 is right up your alley. We can
safely say it's the hottest production 350 yet. It'll cut the quarter very close
to 14 seconds flat in capable hands, and buzz past the 100-mph mark as if it
really wants to. The reed valves account for some of the superlative speed, the
new six-speed gearbox for the rest. Coming off a standing start you must be
careful feeding in the clutch at high-rpm: wheelies are easy. First gear is very
low, and the first few times you try maximum performance runs you'll find the
bike overrevved somewhere around 9,000 rpm before you hit second. The best
possible thing to do is shift out of first a bit early and really hang on to
second. Shifting at 8,500 puts you into the next gear at about 7,500. When
you're wound out in third, not more than five seconds later and a glance at the
speedo will show you 60 mph as you catch fourth, and then fifth, then sixth. You
can hit 80 mph in just a shade over 10 seconds; that's really blinding speed for
a street 350.
For all its
ferocious energy at high speed, the RD 350 is utterly tranquil when starting and
at idle. From cold, the bike rarely required more than two prods to start up.
The proper starting procedure is choke on, throttle off and kick. Once warm the
RD 350 is as easy a starter as there is. The engine never forces you to give it
a full run-through with the kick starter: it immediately starts off with the
orbit of the first piston to pass compression. The engine starts so ridiculously
easy when warm that we had the habit of boggling the minds of disbelieving gas
station attendents by reaching down and starting the engine by hand! With the RD
350 you get practically every conceivable extra, save for an electric starter
which really is unnecessary. New this year is extra instrumentation on a matte
black panel which stretches between the tach and the speedo. There you'll find
four warning lights and the ignition switch. The lights indicate both left and
right turn signals individually, high beam and the rear stoplight. A
double-position on-off-on kill switch is located by the right twist, easily
within thumbs reach in an emergency. Also on that side of the bar is the on-off
switch for the headlamp, which also can be operated without removing your hand
from the grip. A blink of high beam makes a good signal for other traffic when
the rather feeble horn fails to attract their attention. On the left side of the
handlebars is the turn signal switch.
Other nice
touches include a locking gas cap, which absolutely refuses to leak, and the
flip-up seat, which also locks. Under the seat there is provision for hooking up
your helmet, so that when the seat is in the down position and locked, your
helmet is secured also. The fourth and last lock on the machine locks the
steeringhead. All four locks, praise be, can be actuated by the same key.► |
