Didn't 900 come with adjustable air shocks?
cb900c did, talk here is about cb900f reservoir shocks...c and f bikes are very different, really only related by the same motor
incidentally, those 900f shocks still do exactly what the reservoir is supposed to prevent, heat the fluid and then they get mushier...so, you start out on a ride thinking "Wow, these are great!". 20 minutes of thrashing later they are nearly as crappy as stock cb750 units.