Introduced in 1976, the Yamaha XS400 appeared at a time when the major manufacturers were anticipating the end of the two-stroke era and turning their attention to developing four-stroke road bikes. The mid-displacement XS was designed more as a reliable work vehicle than a sports machine, competing with models such as the Kawasaki KZ400, Suzuki GS400 and Honda 400 Hawk.
The air-cooled twin-cylinder offered 45 hp of power and was faster than most of the competition. It wasn’t bad at all, but the little four-stroke 400 wouldn’t win any road riders over.
Roman Juriš from Slovakia acquired this ’84 XS400 as the basis for a comprehensive build.
More importantly, Roman wanted to test a new front suspension concept he has been developing, a progressive inverted suspension fork assembly (PUSDF) designed to minimize movement during braking – a system he is patenting. There are three patent applications:
1. Progressivity – for example, for a 120 mm wheel travel, there is a 60 mm lift in the fork.
2. When springing, the axle of the front wheels is pushed forward, thus eliminating the shortening of the wheelbase.
3. Separation of spring force and braking force – the bike doesn’t sink during braking.
Roman built the entire frame from scratch and the XS now has a shortened YZF125 swingarm, supermoto wheels, a custom fairing with a beautiful paint job and a unique front suspension set-up:
Get to know this model with its innovative and unique mechanics.