Anyway, back to 1983 where this IT490K comes in. It represents the high water mark of the IT range. The most powerful IT with the best suspension – featuring linkage monocross rear suspension, a serious upgrade on the cantilever of the year before.
Being closely related to the YZ490 motocrosser it was awarded the reputation of being quite the beast, but actually, being retuned for enduro, the peak horsepower was around 35hp, a number far exceeded by today’s 450s. Of course in 1983 there wasn’t the kind of digital engine management modern bikes benefit from, so yes, it was still quite lairy, but the YZ was the real monster. In fact, our recent test of the 2016 WR250 two-stroke put us in mind of the IT490, for in both cases Yamaha lowered the compression ratio and lowered the exhaust port to reduce the power and create the more torquey mid-rangey kind of power needed for enduro.
The IT490 was only marginally lighter than the IT400C, measured back in the day at about 112kg, but of course the 43mm forks and monocross shock were much bigger units. The whole bike was much bigger, taller in fact, with 12-inches of travel front and rear. The bike was slightly let down by its suspension for the forks lacked any external adjusters while the shock, although of the newest linkage type, had only preload and rebound damping adjustment. Many riders found it under-sprung as well and would substitute the stiffer YZ490 spring. Over time many substituted the entire YZ490 suspension package, front and rear, for serious competition use.
As was very often the case back in the 1980s, the exhaust system was fairly restrictive, and so – as with our test bike here – it was common to substitute an entire aftermarket system, such as the DG system seen here.