The Motorbike Archives

If one is at all familiar with Yamaha's latest line of YZ motocrossers, it will be apparent that there has been a lot of parts swapping between the YZ 125 MXer and the IT175 off-roader. And though there is much similarity, there are individual differences based on intended usage.

An overall look at the new machine will point out the very close resemblance to the two larger ITs, the 250 and 400. Each share color schemes and concept, just in different dosages. The IT400 was the one that introduced the line back a little more than a year ago. Response was good enough then to increase the line to two other displacements, but the first 1T400 and the present one are vastly different motorcycles, the new being kind of an updated generation.

Most of what took place in the development of the IT 175 was done by the Japanese with very little in the way of direct American input. While the people at Yamaha in the U.S. were running their large-bore ITs in ISDT Qualifiers and the ISDT, they were learning much about what was needed in the way of improvements and requirements. The Japanese listened to what they had to say about improving the 400 and carried the same ideas and features out on the two new ITs, without the Americans really saying, "Do this and do that."

While the engine is similar to what's been offered in the past, it is safe to say the engine is basically new. The mid-sized competition enduro class demands quite a bit and quite a bit is what we're getting here. Crankshaft and barrel are similar to those found in the old YZ 175C, but not the same. A new smaller connecting rod is used along with new porting and a special double walled (for noise reduction) exhaust pipe with approved spark arrestor/ silencer is a big factor in how the powerband works.

A 175 can use a good selection of gear ratios and the IT has just that. With six speeds the little Yamaha has the right ratios for just about any circumstance, from a crawl through the rocks to an all-out, high-speed run across the desert. Coupled with the unusual type of powerband, it's pretty hard to get the IT into a situation it can't handle.

The 175 is unusual because it's almost as though it has a double powerband. There is much in the way of pulling power down in the low rpm range, a kind of relaxation point, then there's an upper pulling range. This should not be taken as being a pipey sort of combination. It's anything but. It is different, however, and very pleasant. The single 34-mm Mikuni carburetor uses a choke lever enrichening device for cold starts and performs well under a wide variety of circumstances. Even the stock jetting remains about right at varying altitudes, pointing out how easily the engine conforms to different riding situations without fuss or bother.

In case a jetting change is required, it's easy to swivel the carburetor around to pull the bottom or top off in a matter of a few minutes. Air filtration is via a fuzz/ foam oiled element that snugs inside a plastic still airbox assembly. To gain access to the filter, one must remove the Phillips screw that secures the side cover/number plate and the three Phillips screws that hold the airbox cover in place. The air intake is very high, to help prevent water from entering during stream crossings. In case water does manage to get in, there is a nice sized drain hole to make sure it exits quickly. Yamaha has really done a nice job of designing the airbox to fit around the monoshock unit which encroaches on space quite a hit in the normal airbox area.

It is easy to be impressed by this machine's quiet presence. It is not the least hit offensive. In addition to the double walled exhaust pipe mentioned earlier, there is liberal use of rubber blocks in the cylinder and head finning to hold mechanical noise down. Air intake noise is low as well. It is pleasing to have a machine so quiet and yet so quick; nothing has been lost in the process.

A nice touch is an aluminum skid pan that serves to protect both the double downtubes of the frame and the engine cases and side cases. The plate can also be removed quickly if necessary. The nice touches don't stop here.

The IT uses its own suspension components, virtually identical in appearance to the units found on the YZ125D, but with different damping rates and a shorter travel monoshock unit. We feel the IT 175's suspension is just about spot-on for most of the riders who will buy this type of machine. Only the very fast and serious jockeys will opt for the longer travel mono unit that is used on the 125, particularly if much of their riding is done in the desert, where higher speeds are commonplace. A woods rider would be wasting both time and money to make the swap.

Forks feature protective rubber gaitors and forward mount axle design and can be raised or lowered in the triple clamps to affect changes in steering geometry. A first for Yamaha here is the use of tapered Timken roller bearings in the steering head, definitely a quality touch. The triple clamps are of the flat design we now see with the use of forward axle forks.

We had our Yamaha test machine running in a great variety of terrain with the riders having varying degrees of skill from amateur to professional. Every one of them went away saying nice things about the machine and gave very little criticism. The suspension absorbs small bumps hit at slow speeds and big bumps smacked at fast speeds. That means if you're on a leisurely trail ride in the woods, it will be comfortable. It also means that if you're competing the following weekend in a national enduro at anything but a leisurely pace you won't be bothered by failings in the suspension system. It is the kind of bike that can be used by several members of a family, regardless of their ability. That makes it a bargain, particularly when one considers the $995 price tag.

The color impregnated fenders are super wide for good protection during muddy excursions and are unbreakable as well. The tank and side covers follow suit. Each are of flexible plastic that is light in weight. The tank has a good sized screw-on type cap that is easy to grip with gloved hands and conceals a large opening in the tank so the rider can fill up with pre-mixed fuel and see when to stop pouring.

Enduro-legal headlight and taillight are used, not the best for riding at night but better than nothing if you happen to be caught out after dark. Each is mounted in resilient rubber as sort of a shock mount to preserve the life of the bulbs. An on/off switch is provided along with a high/low beam switch. Below the lighting controls on the left handlebar is a neat rubber-sealed kill button in an easy to use and reach position.

Back behind the comfortable seat on the rear fender loop is a handy and useful tool bag that bolts to its own support bracket. The machine comes with a fairly standard Yamaha tool kit: a couple of open end wrenches, pliers, spoke wrench, box end wrench, Allen wrench, spark plug wrench, screwdrivers and holder and a special 32-mm open-end wrench to change the pre-load setting on the monoshock unit. The tool bag has enough additional room to store extra plugs, tools, shop cloths and a small first aid kit if you pack it right. Even the owner's manual contains much in the way of good and useful information. We hope the owners of IT 175s will put the manual to use.

Naturally, no enduro machine would be complete without a compact, neatly installed, accurate speedometer and odometer assembly. On the IT this unit mounts just behind the front number plate above the headlight; a fairly well protected yet easy to reach and read location. The speedometer face reads (unnecessarily) to 100 mph (an off-road rider really doesn't have time to read anyway.

The glaring fault is with the odometer portion. It seems as though after the unit is reset either forward or backward (as one would be doing during a timed enduro at checkpoints) and the reset knob is clicked back into normal position. the trip portion of the odometer (the important part) doesn't begin recording mileage again until after about at least an eighth of a mile has elapsed. This in effect makes the resettable portion of the trip odometer worthless to an enduro rider, making us wonder how such an item got by Yamaha. After checking around a bit, we discovered this wasn't a fault of our particular test machine. It can be found on the majority of ITs. We're told one solution is to install the reduction gear out of a Honda MR series machine, but we haven't had the chance to check it out.

Back to a good note, the brakes. Yamaha has certainly found the answer here, because the IT 175 can stop quite controllably from all the speeds it's capable of. The units give the rider good feedback or feel, preventing unexpected lock-up. It also takes a heavy dousing in water to get the brake units to show any signs of fade because of wetness. Recovery time is rapid.

The superbly strong and light Yamaha hubs lace to D.I.D. rims with 36 spokes. Tires are motocross-type knobbies from IRC or Bridgestone, a 4.10 x 18 in the rear and a 3.00 x 21 up front. Either wheel can he changed in a matter of seconds with some practice, because certain design considerations were built around ISDT criteria.►