Cycle News - Archive Issues - 1980's

Last year, Yamaha began to change things by giving the IT175J the latest suspension, Unfortunately, they left the big bore ITs the same. This year, the ITl75 remains the same and the big .bore riders get the full YZ treatment - and there's good reason for them to be exci ted. The changes in the new IT are evi-' dent at first glance. In the looks department, the IT is still blue with yellow graphics,but a safety type seat .and the new lines of the side panels and gas tank set the bike apart from the ITs of the past. The headlight is .now square and the taillight is larger. We've already heard rumors of riders experimenting with accessory square headlights that may easily adapt to the IT housing, so new owners may have an additional feature to be excited about. Just keep an eye on the electrical system specifications listed in the manual when making modifications. The biggest ch anges for the 1983 big bore IT are the increased engine displacement and the addition o f the latest YZ suspension. The IT has been bumped up from the 465 to 49Occ, as the YZ was last year , but the suspension changes are the greatest news . The IT has gained the new YZ configuration that lowers the shock in the frame, thus lowering the center o f gravity. This helps tremendously, because the old ITs were terribly top heavy ; A certain amount of this is hard to avoid in an enduro bike with a large gas tank, but this change is definitely a move in the right direction. Susp ensio n Owners of new ITs will also be happy to know that the new IT sus - , pension offers every rider plenty of adjustability. The IT rear shock still comes without adjustable compression damping, but there are 25 settings for the rebound damping. There are also heavier and lighter springs available for the shock and the fork, and they are compatible with the YZ line if you need even more adjustment. There is a lso an adj ustrnent for preload on the shock, but general ' suspension tuning dictates that this should be reserved for minor changes; the cost of a new spring is small com, pared to the gains if it is needed. Despite all the adjustabiluy, many ,IT owners will never need to adjust the bike. Our testers adjusted the suspension for their own needs in com~etitiori, but we felt that the suspenSIOn was pretty close as delivered. Yamaha forks have always worked well and the new rear suspension complemented that with a plush ride over enduro type terrain. When it came time for motocross or desert, we had to increase the rebo und damping , a couple positions and stiffen the preload and the fork, but the change from enduro type terrain to jumps and whoops is a big one and the rider who learns to adjust his suspension will receive his just rewards in a cornfortable ride. • The frame that carries the IT suspension is basically the same as the YZ, and that is why the suspension is so compatible. The only real differ" ence between the bikes is that the steering head is moved back 20mm to make the bike more nimble in the trees and rocks . For owners of the old IT465s, this translates into a reduction of both trai l and rak e, and it reall y works. We entered thebike in a dese.rt race with several tight rocky secuons and not only enjoyed the easy handling, but smoked our class in these sections as well. Wh en it • I • • , ,. . • • ~ • • • .' .. came to the rough fast sectio ns, however , the rider really had to work to keep the busy machin e going in a straight line. The IT is an enduro bike and handles like one. Given a little longer travel and stiffer sp rings, however, we're sure the bike would be plenty serious for desert. Powerplant The IT490K motor uses essentiall y the old IT465 transmission with a new cylinder and a longer piston stroke. The only other changes are little technical ones here and there in the engine that either reduce weight, or increase reliability. Thicker fin bases on the cylinder and head improve cooling efficiency. What all the technical changes in the IT motor boiled down to was a smooth, predictable motor that is none too slow. We had fun climbing hills, riding wheelies and trail riding the IT. T here are no surprise bursts of power, but there is plenty of top end speed provided through the five speed transmission. Acceleration will challenge your ability to hang on if you grab a handful, but you can dial what you need any time. With the amount of power available in an Open class bike, this kind of rideability becomes the key design goal and the IT490 passes the test. Arrow-chasing goodies The IT still carries basically the same enduro hardware it 's had for the last couple of years . There is an odometer, a pair of the popular IT handguards, a tool kit , a headlight and taillight, a new and simpler thrott le assembly and the quick change wheel setups. The taillight wasn 't working when we got the bike and the headlight burnt out right away. Keep both bulbs in working order or buy' a voltage regulator. One tip for those interested in making an IT street legal; a third wire is provided to the taillight for a brakelight switch. ' Th e tool kit received a change this year in that now the sparkplug wrench -. . socket is welded to the wrench to make servicing easier and faster. Now if only Yamaha would supply a wrench that riders could use to remove the wheel axles when out on the trail. We're glad to see the folding shift and brake levers are here to stay, but we wish the shift lever had been set up for a smaller boot size. Our test rider with size 917 boots had sore toes for severa l days after reaching for the shift lever. Accessory companies will solve this problem and make a buck. While we're nitpicking, the only other complaint we had about the IT was a little one concerning a compromise between weight and styling. The bike received a lot of styling changes for 1983 and a loss in weight that was due to the total savings of a fraction of an ounce here, and another there. With such careful attention to weight savings, it seems a shame that the gas petcock was placed on a section of the gas tank that prohibits the gas in the low rear sections from being used; this translates into dead weight that is placed up high on the bike. As excited as we are about all the other ,improvements this year, this seems a painfully wrong compromise. O ur Impresston The IT490K has been completely redesigned to meet the needs of enduro riders .a nd trail riders, as well as to serve as a good base for modification for other forms of off-road competition. With the exception of a few details, the IT does all this and more. It is a competitive enduro bike that meets the needs of trail riders as the motor is mild mannered; the bike handles well and it finally has the latest suspension. But what's really important to us is that Yamaha has done all this technical stuff for us and now that this i~ a ll down on paper, • we can go bac k to riding IT. Specifications Engine Type : A ir cooled two-stroke. Displacement 487cc. Bore x stroke , ..... •. . ... .... . .•. .. ... 87 X 82mm. Oil capacity : 0 .85 U.S. quart. Compression ratio 6.7:1. Starting system . ; . . . • . . . . . . .. .. . . • . . . . . . . . . . . . . . . . . . Kickstarter. Ignition system C.D.! . magneto. Spark plug Champion N-3C. Transmission Constant mesh. five -speed. Carburetor Mikuni VM38SS . Frame ,Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Double crad le. Front suspension /travel 11.8 in . 1 1.8 in. Rear suspension/travel. 3 .00-21-4PR. Front t ire 150/80-18-4PR. Rear tire D imens ions Wheelbase Seat height M inimum gro und clea rance Dry weig ht (cl ai m ed) ' Fuel capacity Suggested ret ail price ' ' 58 .5 in. 37.2 in. 1 3. 4 in. " . 2 62 .4 Ibs. 3 .6 gal. $2.249 19

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