Text and scans of one of my favourite bikes (IT175) from "Circuit", the Yamaha published mag of the 19080's.
"Yamaha’s range of IT Enduro bikes are thoroughly professional off-road competition machines capable of success at any level — a claim backed up by Gold Medal successes in the International Six Days Trial and wins in innumerable enduro events in both Europe and the USA.
Three models are offered for 1980 all based on Yamaha’s Grand Prix-winning YZ motocross racers but comprehensively modified for the added rigours of enduro competition.
All three models share the super-handling, monoshock chassis of their YZ counterparts, right down to the latest separate gas cell shock absorber with 30 positions of damping adjustment.
They also share engine specifications, but with cylinder porting modified to provide a wider spread of power capable of dealing with the offering terrains encountered in enduro events.
The IT 175 is basically similar to the air-cooled YZ125 motocross machines sold up until this year. It’s light weight coupled with the power and added torque of the bigger 175cc motor make it an especially good contender in enduro's where the going is tight and tricky.
All three machines feature full lighting equipment, flexible mudguards, a sump guard to protect the underside of the engine from rocks and tree roots, hand protectors guarding the rider against tree branches intruding on narrow trails, quickly detachable wheels, easy-to-remove high level air filter, deep-cushion seat and a large capacity petrol tank specially designed so that the rider can still keep his knees tight to the centreline of the bike.
‘In short, the IT Yamahas have all the ingredients necessary for enduro success and have proved it by ‘clean sheet’ efforts in the toughest one of them all, the ISDT - so rightly known as the "Olympics of motorcycling”."