Yamaha It250h
YAMAHA IT250H
CYCLE WORLD TEST
From Last Place to Winner in One Model Year.
Yamaha was one of the first Japanese motorcycle manufacturers to get serious about enduro bikes. The tradition began in 1968 with the DT-1, a street-legal machine that was so exceptional for its time that many were stripped of road gear and became serious and successful enduro and motocross racers. Later came the ITs, with single-shock suspension and motocross-derived engines and if some of the first ones veered from the trail or kicked when not watched, still, they had power and every model year saw more steering precision and improved suspension. Rival factories have been doing as much work though, and last year the 1980 IT250 took a drubbing in our enduro comparison.
Because that didn’t match what we’ve come to expect, and because a quick walk around the 1981 IT250H shows that’s it’s changed in just about every way possible, the IT250 was our first request for a Yamaha enduro bike this year.
We weren’t disappointed.
The frame is last year’s motocross frame with the proper enduro changes to it. A rear frame loop has been added so the long rear fender has good support, and small tubes commonly called six-day bars have been added under the sides and bottom of the engine. These bars protect the cases from rock damage but don’t fill with mud like regular skid plates. Thus the bike doesn’t get heavier during a mud run and engine cooling isn’t blocked as it is with a normal skid plate. The rest of the frame is the same as last year’s YZ. It’s chromemoly steel, highly braced and stiffened with boxed-style gussets. Backbone and downtube pipes are large diameter tubing, smaller tubes tie the large pieces together and form the necessary triangles under the seat and engine. The new frame proved strong enough for the motocrossers last year, so it should hold together forever on an enduro mount.
The motocrosser likeness extends to the aluminum swing arm and aluminum bodied remote reservoir shock. The shock placement, length etc. is the same as the MXer. The difference is in spring and damping rates; slightly softer for the IT Like the motocrosser, damping is easily adjusted with a twist of the fingers and spring preload only takes slightly longer.
The boxed aluminum swing arm on the IT looks much like the one on YZs and is. The main difference lies in the axle slot—it’s open at the rear so the axle and wheel can slide out the back in one unit.
Suspension is finally a high point of the IT. Travel at both ends is just right, 10.6 in. Leading axle KYB forks with 38 mm stanchion tubes, lots of up and down adjustability. Double bolt triple trees and a four-bolt axle clamp take care of the front. Air caps are installed but Yamaha recommends trying the bike with 0 psi. Of course they can also be adjusted by changing oil volume, changing oil weights, or replacing springs with softer or stiffer ones that’re available through Yamaha dealers.
The IT250H gets the smaller case MX engine. Of course cylinder porting, carburetion, pipe, silencer and transmission ratios are special for the IT’s intended use. The MXer went to a five-speed for ’81, the IT retains the six-speed—more gears are usually best for enduro terrain. Like the YZ250, the IT250 is fitted with a plastic box that’s connected to the intake tube just in front of the six-petal reed cage. The system, called YEIS by Yamaha, improves low speed response and torque. The idea is, when the reed valve closes and pressure behind the reed increases, the pressure fills the box with premix instead of reversing itself and going backward through the carb; when the reeds open again, the stored fuel is instantly drawn into the engine. Of course the cycle happens hundreds of times a second.
The rear hub is a new item that’s shared with the motocrossers. The spoke flange on the brake side is thicker and the aluminum sprocket is held on with tapered head bolts, not studs as before. The new bolt system is much stronger and should eliminate the isolated bolt shearing some hard riders experienced with the studs. A wide smooth aluminum rim is laced to the hub with larger spokes. The front wheel is also different. The hub is the same but larger spokes are used and the brake is equipped with the brake cam from the 250 motocrosser. The cam increases the power of the brake. Both tires are the rim saver type, meaning the tire rolls around the rim slightly and adds protection when riding in rocks. They are made by IRC but have square dimples in the knobs, like Dunlop’s K190.
Equally impressive is the list of enduro items and time-saving devices included as standard quipment. There are pull bars on both axles, water drains on both backing plates. The side stand has an oversize foot so it won’t sink into soft ground. The brake and shift pedals fold. The frame has mounting lugs for an add-on center stand. There’s a sturdy tool bag on the rear fender. The seat bolts thread into the frame so there are no nuts to lose and the seat can be removed with one hand and one wrench. A plastic guard shields the chain from mud hurled off the rear tire. The kick start lever has a ribbed surface. The air intake is high on the bike. The air cleaner is easily reached without tools through the side of the airbox. Hand guards are standard. The headlight num-
ber plate is quickly removed by hand. The odo has a large reset knob and a magnifying lens, the snake headpipe is raised above the lower frame tubes to prevent damage, the silencer is quiet and equipped with a forestry legal spark arrester; tricks are every place you look.
Much thought has gone into the rear wheel on the ’81 IT. It can be removed with one wrench if the vertical pins in the axle slot are removed and left out. (They aren’t necessary anyway.) The brake backing plate doesn’t use a regular static arm. The plate slides into a tongue on the swing arm, eliminating the need for an arm and the problem of one hanging up on rocks
and logs. The brake rod still has a quick release device and a bracket on the swing arm holds the rod out of the way while tha wheel is being worked on. When the axle nut is loosened, backoff the snail adjusters and slide the wheel forward. Roll the chain off the rear sprocket without bothering the master link, then slide the wheel out the back of the swing arm slots. It’s quick and painless. s
The IT’s dimensions are as important as its specifications. Wheelbase has been increased by 1.6 in., to 58. 5 in. Space allocations within that are greatly changed, as‘ the swing arm is now 21.3 in. long, a radical gain from the 17.8 in. swing arm used last year. The longer arm means the bike slides with more control, and power on a hill means the rear wheel digs in instead of the front wheel leaping up. The forks are pulled back a fraction, with steering rake at 29° instead of 29.5°, for quicker turns in the tight stuff. Usually steeper rake means less trail, but the engineers redid the offset of triple clamps from steering stem and added trail, so the 250H snaps between trees better and tracks at speed better.
Fitting that new swing arm inside the wheelbase gave another improvement, also thanks to the new engine cases. The swing arm pivot is now only 2.9 in. from the countershaft sprocket, compared with 4.5 in. last year. Less distance, less change in chain tension with wheel travel. The bars are narrower, 33 in. vs 34, which quickens the steering but is still wider than the gaps between eastern trees. As a final fraction, despite the added wheel travel at both ends, static seat height has risen—clever!—by only 0.2 in.
Where sharing makes sense, for example the shorter dog-leg levers, the straightpull geared throttle and the waterproof kill button, the IT and YZ share parts.
Where sharing wouldn’t work, the IT is different. The old straddle-a-watermelon tank has been replaced by a larger one, 3.4 gal to 3.2 for ’80, and the larger tank is wider at the front, narrower at the rear so the rider can move around more easily. Plus, the top of the tank is flat, just right for an enduro score card. The petcock is traditional Yamaha, with down for go, sideways for stop and straight up for reserve.
The all-white IT looks as serious as it is, and most riders who saw the new model liked it.
It performs as well as it looks. Steering, something no previous IT has done really well, is great. The front tire bites into corners and follows the rider’s line, while there’s no wander at top speed and the old monoshock kickback is gone ... or if it isn’t, the rider can dial damping and preload until it works for him.
The light clutch doesn’t slip or drag, there’s primary kick start of course and if most of the mid-range punch comes from the new engine, well, the gear ratios match up with no gaps.
Starting is much improved for ’81. Cold starts are usually a two kick affair, warm starts one kick. Warm-up is rapid and the engine doesn’t cough or blubber when taking off after minimal warm ups. The IT’s new larger silencer emits an acceptably quiet sound and shouldn’t offend many.
The new engine has a much improved powerband and overall power. Mid-range power is a wide smooth band that starts at quarter throttle and continues past threequarter throttle. Low-end power still isn’t a match for Kawasaki’s KDX or Can-
Am’s Qualifier but its not bad. Engine tuning is intentionally aimed at a wide mid-range and low and top-end power are somewhat subdued as a result. Thus, the engine’s power matches the rest of the new IT’s image; a serious enduro bike for medium to expert riders. Novice and C riders may have a little trouble with the power transition from the frist quarter of the throttle to the mid-range. Level ground won't pose a problem, hilly terrain may take a little practice. If the engine power drops into the first quarter throttle while part way up a hill, it’s hard to get back into the mid-range without downshifting. And the first quarter of the powerband doesn’t deliver outstanding performance. Making it over the hill won't be a problem; low will take the bike nearly straight up. And as long as an aggressive pace is maintained, the bike will rocket over the top. If the
rider has to slow for any reason, regaining the lost speed isn’t easy. Hitting or fanning the clutch motocross style doesn’t work on the IT. Downshifting is your only choice. Again, aggressive riders won’t have any problem, C’s will need a little practice. Most riders adapt quickly.
The new IT250 is such a good bike, we had trouble finding much wrong with it. One small complaint was voiced by a coik pie riders though. Changing idle speeds requires loosening a lock nut first. Kind of dumb on an enduro bike. A large plastic knob like Kawasaki’s KDX uses would make adjustment quick and easy without tools, a minor but sometimes important function.
Faulting the overall handling of the IT is hard. It does almost everything well. The brakes are strong and progressive, position on the bike is nearly perfect. steering is great, tires are very good, spokes don’t loosen excessively, the seat is comfortable, the tool bag doesn't protrude above the seat where it's in the way—yet holds a good supply of tools, fenders protect the rider well, the odo is easy to read and reset—although the ultra quick reset has been dropped, and the six-day frame rails protect the engine well. As a bonus, the '81 IT is 10 lb. lighter than last year.
YAMAHA IT250H
$1899
Yamaha’s ’81 IT250 looks and sounds impressive because it is.
Sounds good, huh? Last year was painful. The 1980 IT250 drew as tough a review as w'e had all year. Not even the factory had much to say about that, because what we wrote w;as what we got. We can’t take credit for the improvements, though, because the '81s were designed before the comparison was in print.
If the rest of the IT line is like the 250, you can expect an invasion of white bikes on the starting lines at enduros across the nation. And, you can look for many of them in the winner’s circle.
