Yamaha Street And Trail Minis
YAMAHA STREET AND TRAIL MINIS
The Ever Popular Mini Enduro Gets A New Riding Partner
Cycle World Road Test
TO ADULTS, the term superbike is reserved for a rather unique 750cc or larger machine with two things going for it: unbelievable performance and styling to match. To teenagers just getting into motorcycling, though, bikes like this are no more than dreamsdreams which may become reality some day, but dreams nonetheless.
Still, for the pre-teen or teenager, reality does exist in the motorcycle world. There are even superbikes. Industry calls these mini-cycles, and in this field Yamaha was first with its off-road Mini Enduro.
For '73, Yamaha has improved the enduro and has introduced a mini-roadster called the RD60 for those with a touch of Ago in their blood. Because it's the newer model of the two, let's consider the RD60 first.
As far as styling goes, RD could very well stand for "racing department." The gas tank is very long, slim, and blends gracefully into a short but amply padded seat. The seat is curved up at the rear and has an end section, similar to those fitted to racing machines. A regular fender, however, protrudes beyond this and forms a mounting area for the taillight and turn signal assemblies.
Up front, there is a low mounted chrome front fender, a generously sized headlight, a speedometer and even a tachometer. The tach, incidentally, is red lined at 10,000 rpm and if you persist, the little Single will just touch that figure in the lower gears.
Thoughts of turning 10,000 revs and that styling kind of makes you wonder whether or not the bike is a noisy, tempermental bullet. Happily, this is not the case. The 60cc, 4.9-bhp Single starts on the first or second kick every time and at idle, it can hardly be heard at all.
Ease the machine into gear, it's a five-speed with a standard down for low shift pattern, and begin to let out the clutch. There isn't much power down low so you either have to ride the clutch or put up with a sluggish start until the tach needle nears the 6000 rpm mark. Here the engine begins to pull strongly and continues to do so right up to indicated red line.
The rpm must be kept up, but it isn't objectionable on the RD. In fact, if the tach were disconnected, you'd never believe the crank was turning that fast. There just isn't any vibration, intake roar, or exhaust noise, to indicate the rpm. Yamaha has really done its homework in this area.
Gear selection is precise and this aids acceleration considerably. If you really get with it, 23-sec. quarter mile times in the 52 mph bracket are possible and that, friends, is just about as fast as a 40-bhp VW.
Armed with this knowledge, and keeping in mind the fact that a VW has a lot more top end acceleration and speed than an RD60, we ventured out onto the boulevard. Surprisingly, the tiny Yamaha keeps up with city traffic quite nicely and is actually a delight to ride around.
Handling is incredible. Steering is so light it feels as though it is power assisted and the bike can be flicked through a series of bends with ease. Decreasing radius turns are particularly delightful because you can lean the RD over at crazy angles and still nothing drags.
On rough streets, the ride isn't particularly harsh, but you do run into the definite pogo effect found on a lot of small bikes. The cause is inadequate damping in the rear suspension components, and the only cure is substitution of better spring damper assemblies. If you go this route, however, make sure the spring rate is the same as stock.
Unlike the rear, front suspension is superb. Front forks are oil dampened internal spring units with rubber boots to keep road dirt and water out of the oil seals. They are perfectly capable of handling any common road irregularity and only bottom occassionally in chuck holes with a 160-lb. rider on board.
With its 17-in. wheels, double cradle frame, and willing engine, the RD is right on in every respect but one: brakes.
The brakes are single leading shoe both front and rear and quite frankly, are not capable of halting the bike repeatedly from top speed (52.91 mph) without considerable fade. Also, the front brake feels spongy, indicating that the outer housing on the cable is compressing slightly when the lever is withdrawn. Fortunately, around town at slower speeds, the problem does not arise. It's just that we like to have a greater margin of safety than the RD60 units provide.
So much for potential Agostinis. Take a turn off-road and enter the realm of the 80cc GT1, Yamaha's updated Mini Enduro.
The Mini Enduro first appeared in 1971, in 60cc configuration. That original was also for off-road only. Add a larger 80cc two-stroke Single and full street legal equipment and you end up with Yamaha's current offering.
As we've just indicated, the basic package and concept is unchanged. In fact many of the components on the 80 are interchangeable with those fitted to the original. Wheels are > still 15 in. in front, 14 in. in the rear with 2.50 and 2.75-in. cross section tires fitted respectively. The frame is still a tiny double cradle unit with a skid plate welded in place beneath the engine. And, fenders and gas tank still have the same flare.
Forks on the new model appear different, but this is because the newer units have polished sliders whereas the originals were painted the same color as the gas tank. These forks are adequate, but are not as good as those found on several other minis. Most forks are like those found on the RD60 with springs and damping units in each leg. Not so on the GT1. Here we find a spring in one leg and an oil damper assembly in the other. Bolt the front wheel in place and you have a front end that behaves in a normal manner—only not quite as well as a conventional setup.
Hit a washboard road on the GT1 and the forks top and bottom a lot. Also the front end skates around because inadequate rebound damping lets the front wheel bounce more than conventional forks.
The rear suspension components could stand some improvement as well. As with the RD60, spring rate is fine, but damping is totally lacking.
As mentioned earlier, the GT1 is powered by an 80 instead of 60cc two-stroke Single. Instead of using a rotary valve setup with the carburetor hidden in the engine case, the new engine features a reed valve arrangement with a conventionally mounted carburetor. Surprisingly, the 80 only puts out 0.4 bhp more and is still rated at less than 5 bhp. Apparently the changeover was more in the interest of increased torque and reliability than anything else.
Since the unit is of similar design to the RD60, we suspected a five-speed transmission. Such, however, is not the case. The GT1 still has a four-speed unit with neutral at the top of the shift pattern. Although gear selection is positive, we would prefer a transmission with neutral located between first and second and low gear at the bottom of the pattern. Since the GT1 does not shift conventionally, it is not as good a training device for the novice rider.
YAMAHA
RD60
$359
By today's standards, the GT1 lacks a certain amount of sophistication, especially in the area of suspension. But one thing is undeniable. The bike is an absolute ball to ride. You can pull second gear wheelies on straights, slam on the brakes (they work fine on this one) and dive into a corner in true class C fashion. On slippery surfaces, the front end will push a little, but it's not alarming and the rear end rarely breaks loose. When the rear does break loose, the entire machine will drift to the outside, slowing as it drifts. Spills should be rare.
Like most small bikes, however, the GT1 is not a jack of all trades. When negotiating soft ground the front end plows and there is barely enough power to keep the bike going. Likewise, caution is advised on streets (the GT1 does come with full legal equipment). The machine is very small, will be difficult to see and will just barely exceed 45 mph. This is fine for mounting roads or for riding within national parks, but for little else.
There you have it, Yamaha's minis for street and trail. The GT1 offers a lot of fun for the money and the RD60, well, it's got to be one of the cheapest ways to get around town! EO
YAMAHA
80GT1
$356
