Yamaha Ty175
YAMAHA TY175
Cycle World Road Test
A Better 175 Than Most 250s Are 250s.
WHEN A JOB is difficult, it isn’t rare to experience the thought, “If I only had a larger hammer or wrench, this would be much easier.” People often find them-selves caught up in the “bigger is better” syndrome. The larger, stronger, more powerful, more expensive something is, the better job it can do. Or so they think.
In trialing, until recently at least, the rule has been followed without exception. Montesa’s 250 Cota is an overall better performer than the Cota 123. Honda’s TL250 outperforms the TL125. Bultaco’s 325 Sherpa T was the cause of the demise of the 250T. But Yamaha has introduced a mid-size trialer with enough improvements over its existing TY250 to more than make up for the larger machine’s power advantage.
The TY175 Yamaha “Cat” is notas large a motorcycle as the 250. Physically, it is a scaled-down version. The bikes do share a few items; but for the most part the 175 is its own machine. Although more diminutive, it will easily fit any rider shorter than a full six feet in height. Even though the advertising you may see will tout it as a youngster’s trialer, it has been endowed with enough of the basic trials characteristics to perform well with adults aboard.
The whole engine looks identical to the 250’s, except smaller. Internally, the power from the engine is delivered via helical gears to an all-new six-speed transmission. As in its big brother, the first three ratios on the 175 are very tightly spaced. Top speed is surprising, considering the machine’s displacement and intended purpose.
Ignition is by standard flywheel magneto arrangement. CDI units, which have become popular on street as well as motocross machines, are many times inappropriate in trials application because their timing advance is not gradual enough. The problem lies in the advance mechanism, which is electrically triggered instead of being centrifugally controlled. Yamaha has solved the problem simply by shying away from it. Points systems are not foolproof, but with the limited mileage and low rpm levels that trials bikes see, the life of a set of points should be extraordinary.
The TY175 impressed us in several areas. First, it is extremely appealing to the eye. Second is the machine’s agility and third, its performance.
Styling is not very different from that on the 250,but it has a few touches that make it unique. Yellow, pearl white and black are used in a delightful combination that adds to the trialer’s slim appearance and enhances the sleek and supple image the rest of the machine projects.
In trials terrain the true nimbleness of the TY shines through. This is a machine that, because of its light weight (185 lb. dry), can find its rider exerting too much force. The bike does not need to be heaved around in commanding form as do most 250s, but simply guided in the right direction.
While this is a bike that an adult can do well on, it should be a light adult. The engine (which we’ll discuss next) can easily handle heavier persons, but the suspension is suited to a maximum of about 150 pounds. Damping action at the rear is substantial but not unusually good. The forks feel fine, but are slimmer and don’t sport quite as much travel as the 250’s.
Sliding the legs on our test bike up through the triple clamps about an inch made the machine steer a little heavier (which still wasn’t very heavy at all), and allowed us to turn the machine tighter than would otherwise be possible. The trials events we contested on the TY were full of extremely tight nadgery and several full-lock turns. The 49.8 wheelbase of the 175, along with the quicker steering, made even the tightest turns seem like Sunday drive stuff.
Combining good handling with a proper motor is the dream of every manufacturer. Yamaha has succeeded with the 175 in producing a power plant that can not only perform many things at 250cc level, but that is smoother to boot. The heart of the TY is a 171cc reed-valve, seven-port Single that shares the bore and stroke dimensions of 66x50mm with all other Yamaha 175 Singles. The corrected compression ratio is a lowly 5.8:1, but it is one of the reasons that the Yamaha is so smooth. Another is the size of the Mikuni carburetor. At only 22mm, air speed through the venturi is high, ensuring a finely mixed fuel/air ratio for more complete combustion.
It would be foolish to think that the 175 could produce the amount of torque that 250s can. But this Yamaha produces more than its share of grunt. Most sections can be ridden in second gear, saving first for that occasional “impossible” turn. As the wick gets turned up, the power climbs too, without surges or flat spots. When the juice signs off at about 7000 rpm, not only does the power stop increasing, but the engine refuses to rev any farther.
Lubrication is what you would expect on a two-stroke Yamaha. Autolube injection. The oil tank, which folds out on a hinge from behind the left side panel, holds 0.6 pint and ably handles the petite tank’s 1.2-gal. capacity. A good rule to follow was two tanks of gasoline to one tank of oil. In a particularly difficult event, it might not be a bad idea to check the oil level at each gas refill.
One of the few items borrowed directly from the TY250 is the wheels. Both of them have small hubs and D.I.D. rims. The front hub has a magnesium backing plate and holes are drilled down the entire length of the front brake anchor arm for increased lightness. Braking power is just perfect for trials. The binders do not require a delicate touch, but can be used to bring the machine to an incredibly slow crawl.
Trials seats are noted for being skimpy, since sitting is not one of trialing’s bare necessities. Although the actual surface area does conform to the sport’s less-than-generous specifications, the seat is surprisingly well padded on the TY. Yamaha has made trailing concessions of this sort all through its machine.
The handlebars, which are poorly shaped for trials use, are one such compromise on the TY. The lighting system is standard and raises the retail price. While some folks might want the lighting system, which works very well, it is an expense that is forced upon those who want this trialer strictly to ride trials.
Rather than fabricate a kit, such as the TY250 trail conversion in last month’s CYCLE WORLD, Yamaha has included splined shafts that extend under the engine on either side. These shafts are for trail positioning of accessory footpegs. You should decide immediately whether or not you’ll want to use them, because the first rock that hits the splines will render them useless. If you’re not going to use them, hacksaw them off.
It appears that little can be faulted on the TY175. These last few complaints have been minor ones, but there is one thing that really turned us off. The welds on the bike are so junky looking that anyone getting within five feet of the machine should easily be able to spot the splotchiness. Normally, poor welding on a machine would consist of uneven beadwork or a rare incomplete weld. But these, although they proved strong enough, are disgusting. Many parts, like the kickstand (which interfered with the rider’s heels, as did the brake linkage), are slapped on and incompletely welded or have several jagged tips protruding from the welded spots. These tips are unsightly and dangerous. We had minor cuts on our hands from these sharp little pinnacles after performing routine air filter maintenance. To make the bike look better in this area, once complete, would require a magician. Better if Yamaha took the time to correct it now, while they have the chance.
The chassis design itself is a double cradle unit similar to the 250’s. A small toolkit is carried inside the initial cradle split just below the steering head. The only design flaw we encountered dealt with a junction of the cradle tubes beneath the rear of the engine where they meet the two tubes that drop from the backbone. The distance between the cradle tubes is at least two inches less than that between the other tubes. The cradle tubes are bent sharply outward at 90-degree angles in order to meet the outer tubes at their ends. This sharp bend creates a natural hook under each side of the bike. This hook will snag hard on rocks and logs rather than glancing off. The trail footpeg splines, although they do a bit of snagging themselves, will prevent damage to the frame hook, until you remove the splines.
What is needed then is a piece of tubing, welded at a direct angle from below the mid-engine point to where the cradle tubes now weld, allowing most obstacles to skim off. There would be no decrease in the TY’s already tremendous ground clearance and the weight increase would be unnoticeable.
Another modification we recommend is a straightening of the rear brake pedal. At present it tucks tightly to the frame until the last two inches, then it makes a sharp turn outward. Snagging the brake is far too easy. Correcting this malady would be almost as easy. We wrapped the brake around itself a few times in very moderate trials sections. It doesn’t take much to straighten it or the shift lever, the latter of which we were able to bend into a U usingjust one hand. Too soft.
It other upcoming 175cc trialers perform as well as the Yamaha, then this smaller class could become very competitive against the larger bogwheelers. It’s just a shame that with such a super little engine, good suspension and very good geometry, Yamaha couldn’t take a little more time to weld everything together with the care and thoughtfulness that is so evident throughout the rest of the bike.
YAMAHA
TY175
$965
