Yamaha It175j
YAMAHA IT175J
CYCLE WORLD TEST
This Motocrosser in Enduro Disguise is Fun, Competitive and Priced Right.
What with all the headlines about umpty-horsepower open class enduro and motocross bikes, it’s easy to forget that size isn’t everything and that sometimes it’s more fun to have just enough of everything and be able to use it.
The IT175 is Yamaha’s way of reminding us. Based on the YZ125, the updated IT175 arrived late in 1980. With more displacement, a milder state of tune and a complete set of enduro bits the IT was an entertaining little rascal. Our only niggle was that the engine wasn’t tuned quite mildly enough; not enough torque and not enough mid-range power. The factory came out with an update and it worked, but still, not quite right.
For 1982, all is fixed. It’s pretty much a new bike, even though it doesn’t look that different, and all the improvements have been done by the factory.
The compact engine looks the same, with cases so contoured around the crank and gears that they look shrink-wrapped. There’s primary kick start, six speeds and CDI, all tucked within the frame tubes.
Inside, though, there’s revised porting for more torque, while the top end is less peaky and the power output is the same.
The exhaust is also designed for better torque and the headpipe is twisted and bent around to provide better ground clearance. It does have better headpipe clearance but the radical twist has pushed the upper part of the pipe, just below the middle of the cone, out the right side quite a distance. We never bumped it on anything but it might make the going a little chancy in a tight boulder-strewn canyon.
The juggling of engine performance allowed juggling of the transmission’s internal ratios, to the bike’s benefit. With more torque at lower revs, 1st didn’t need to be quite as low as before, so it’s closer to 2nd which is now closer to 3rd, which isn’t changed. Meanwhile 4th, 5th and 6th are also moved closer to 3rd. This sounds sort of backward, in that usually the peaky engine gets the close-ratio gearbox and the milder engine has wider gear splits. In fact, the ratios were plain wrong for the first IT175, and the changes get rid of the gap between gears, make 1st gear starts easier and spin the engine right to redline in 6th, with power to keep up speed on soft ground.
Most of the engine specs aren’t changed. Bore and stroke remain 66 x 50mm, the piston still uses two rings and the rod appears unchanged. The kick start lever is still placed high on the right side of the engine’s cases and the countershaft sprocket is set way back. Carburetion is new, a 34mm Mikuni replacing the 32mm.
Yamaha invented the YEIS boost bottle and the ’82 IT 175 has one. The bottle stores intake pulses trapped between the carb and closed reeds, allowing quicker response and better low end power. Another new gadget, one the owner’s manual doesn’t mention, is connected to the intake hose between the airbox and carb. It amounts to a small diameter hose and small plastic box. It looks like another boost bottle but it’s a still-air chamber.
Such chambers used to be common on dirt bikes. Can-Ams used one between the carb and air filter until ’82. The theory is the carb can draw its first breath from the chamber without pulling it through the air filter. Thus, the unobstructed air source allows a more responsive running engine. Past designs had large chambers actually placed between the filter and carb. Yamaha’s air chamber is a small can connected to the air intake hose at the extreme outside of the elbow via a short piece of hose. It’s about a third as big as the boost bottle. The size is the result of extensive testing and Yamaha spokesmen claim it really does make a difference.
Yamaha’s IT250 and 465 have the same rear suspension as last year, while the IT17 5 is fitted with the new Monocross system used on most of Yamaha’s ’82 motocrossers. It has a conventional boxed aluminum swing arm that looks strong enough for a TT500. A short arm and an L-shaped rocker connect the front of the arm to the rear of the shock. The linkage adds progression to the system, meaning the first part of the wheel travel moves easier than the last part, small bumps are absorbed easier and the shock bottoms less on large ones.
The single shock has adjustable rebound damping like past models. Over 30 positions are available by turning the thumb screw at the extreme end of the shock’s body, just above and in front of the rear wheel. Turning the knob clockwise makes the rebound damping stiffen Turning it counter-clockwise makes it softer. Compression damping isn’t adjustable, not with an external knob anyway.
Compression damping can be varied some by changing the nitrogen charge in the remote reservoir. And moving the separator piston in the reservoir 10mm either way from the standard position will change compression characteristics.
The IT 175 frame is now YZ125 derived instead of shared. The IT naturally lacks the plumbing needed by the watercooled YZ, and the enduro version has bolt-on tubes beneath the engine, for protection in rough terrain the MXer isn’t supposed to see. In general design, though, the two are alike, with strong chrome-moly steel, massive gusseting around the steering head and short tubes to triangulate between the top tube and main downtube. Because the shock mounts partially above and partially behind the engine, the top tube is short and divides into two sections that parallel the shock and then drop down to the lower rear corner of the cradle. The downtube also splits, just above the central exhaust
port and those tubes run beneath the engine to the same corner.
Front suspension is very good. The forks have 38mm stanchion tubes and 10.6 in. of wheel travel, more than enough for the intended use of the bike. More travel would mean a higher seat and the newest IT already is rather tall at 36.8 in. Anyway, the forks have air caps for suspension tuning, although we found it unnecessary. The stanchion tubes are longer than you’ll probably need but > being so makes for a lot of up and down adjustment through the double-bolt triple clamps. Pulling the tubes out will raise the front of the bike and slow the steering for those who want to blast through the deserts at high speeds. Lowering the bike on the tubes (more tube above the top clamp) will quicken steering for use in tight woods. If you lower the front be sure to measure tire clearance so the tire doesn’t bottom into the fender and pitch you over the bars. With the bike on a box or something that will get the front tire off the ground, be sure the tire has at least 10.7 in. of clearance between the fender bolts and closest knob.
The little IT175 is completely decked out with enduro-right components. The fenders are large and furnish good protection from mud and rocks, the integral taillight doesn’t catch on the rider’s boot when mounting and doesn’t easily get broken during crashes. A rear fendermounted tool bag provides a place to carry tools or spare parts, hand guards ward off tree limbs and brush and rocks, the headlight/numberplate is nicely made with a smooth numberplate pad and the headlight has a plastic outside lens so rocks don't break it. The odometer has a magnified lens so folks with less than 20/20 vision can read the numbers while bounding along down the trail and a large reset knob makes it easy to adjust the mileage. The shift and brake pedals have folding tips, both axles have pull bars for ease of removal, the chain is tensioned via snail adjusters, the brake rod is one of Yamaha’s quick release models and the swing arm has a bracket to set the rod in when it’s unhooked.
Even the airbox is different. The inlet is high and well protected, and the cover is quickly removed without tools. It’s held firmly in place by a rubber strap that runs across the airbox at an angle. If you drown the carb in a deep creek or crash in one and get the air cleaner wet, removing it to squeeze out the water is quick and simple.
Hand controls are normal for Yamaha: good. Levers are dog-legged, cables are nylon lined and have heavy exteriors, grips are fine and the throttle has the cable exiting parallel to the bars, but it’s not the same gear-driven throttle used on larger ITs and YZs. It has a regular barrel inside and simply has a turned exit nose. If anything it works easier and smoother than the gear-driven models.
The first 100 ft. on the '82 IT175 will tell the rider the new bike is different from last year’s version. Engine power is subdued at high rpm and low speed torque and pulling power are exceptionally strong for such a small engine. Hill climbing ability is amazing. All our testers marveled at how easily the 175 conquered hills. Low gear is needed on the really steep ones and you naturally need a little run before starting up, but no more than you’d need on a 250. Even hills with short approaches and a tight turn at the bottom posed little problem.
YAMAHA IT175J
$1399
Coming down steep hills is as much fun as climbing them. The light weight and agile but stable handling ensure confidence, as do the strong, predictable brakes. Part of one test day was spent in the rocky Rand Mountains, known for steep hills and gnarly, rocky goat trails and old burro trails once used to transport gold and silver ore. It’s a great area and one that quickly separates enduro bikes from motocrossers. The IT was great fun on the twisty trails and shalely burro paths.
The IT17 5 exhibits good manners in almost any terrain. It’s stable down deep sandwashes, steers well on tight trails, stops well, and generally gives the rider a feeling of strength and quality. Frame and swing arm strength are exceptional and the bike feels flex-free regardless of the severity of terrain. Even bone-jarring rock whoops don’t phase the IT. It doesn’t cross them as smoothly as some bikes; the rear suspension simply isn’t as progressive as some designs and the rider gets jarred more but it’s not a major problem. It’ll go as fast as the rider wishes without kicking or side hopping. It’s just a little rougher than ideal. Even so, we went through the open desert with the throttle to the stop for miles. Fast bumpy trails across the desert are really fun, just peg the throttle, shift to 6th and hold on.
The bike is amazingly strong and reliable. Even wide open throttle in uphill sandwashes for miles on end didn’t cause complaint. It just kept going. Riding the bike flat out naturally doesn’t do much for gas mileage. The 2.9 gal. tank is only good for 55 to 60 mi. under these conditions. Riding slower or in the mountains where speeds are lower, increased the range to 75-90 miles.
It’s nice to have all the suspension and handling adjustments but we didn't find it necessary to change any of them from stock. Although the bike is a little rough we felt softening the spring preload would cause bottoming. Too bad the compression damping isn’t adjustable as it is on the YZs. Softer compression damping would probably make the ride more comfortable.
Still, this wouldn’t keep any of the testers from buying one. We all thought the IT 175 was great fun and would be competitive in any enduro, any place. It’s easy starting, fairly priced and ultra reliable. E9
