hi ,
I have CB500-4
I had problems of the brake rubbing to much,pads not retracting,
I cured it by replacing the piston seal,nice fresh and flexible,it pulls the piston back
a treet,
also,if you remove the spring from the adjuster,and let the caliper move as it needs,it
inproves the braking,
the seal cost about £3.50 ish