The XR400 is a great bike. But depending on where you buy it, it may not be equipped for road use. In the USA/Canada this bike was sold as "Off Road Only". Very different bike than a "Road Version".
The US version has a headlight and tail light but nothing else. Stator output is low also. NO battery, NO electric start. Perhaps in Europe its a totally different bike? Generally when Honda make a bike road legal they also change engine internals and many other items.
Example: difference between XR600 (dirt bike) and XR650L (road legal dual sport bike). Basically same motor. One is kick only, no battery, and a race motor. The L version has different piston, cams, Comp. ratio, Carb. , battery, and suspension. Has full wiring Loom and all street requirements. XR600 has almost none of that ... very basic, just like the XR400R.
I owned a '97 XR400. (USA). Mine was converted to street legal using a Baja Designs kit. Very common with this bike back in the 90's.
Very reliable but not really a long range travel bike, IMHO. I took it on a few multi day dual sport rides and on one long Baja ride. I struggled a bit in Baja regards carrying luggage. The bike rode great, just not much room to carry stuff, which is hard in rough off road riding. It's OK on highway if your happy cruising at 60 mph. Any faster and the motor is revving a bit fast.
Several of the most successful Baja bike tour companies still use the XR400 today. This is probably the highest praise that could be offered on this bike. The other bike used is the Suzuki DRZ400E. Both are good, but none of these Baja tours go for more than 5 or 6 days and the riders are not required to carry ... any gear at all.
Everything is provided ... they fix flats and even help you pick up your bike.
The Seat replacement is an easy solution. Any good seat company can make a custom seat for the XR400 or DRZ400. Both would need this to make realistic travel bikes.
Honda stopped importing this bike into the USA in around 2000 or 2002?
Not sure about EU or other markets.