Data wrote:Gio, I've checked an old manual on this. It only shows a piston with the screw driver slot. Maybe your's is a very early variation and just needs brute force to push it in rather than turning with screw driver??. Someone on here must have done it.
This weekend I decided to remove the exhaust, rear wheel and calliper then have a good look.
The calliper bracket was separated from the calliper body and slider pins cleaned and greased. To be safe and prevent any possible damage, I removed the two bolts that held the brake lock mechanism onto the calliper assembly and separated the lock mechanism from the calliper body. With that out of the way I removed the pads then operated the brake lever and carefully let the two pistons get pumped out about 5mm each. I then saw a ring of what looked like a hard salt deposit around the pistons. It was quite hard but removable by a piece of old credit card and then a polish with metal polish. There were no scores so the pistons were retracted by hand then pumped out again so that any polish / debris that was left on the piston could be wiped off. After that both pistons were fully pushed back.
The brake lock piston on the early Y model (year 2000) does NOT screw back like the later models but can be pushed straight back.
The brake lock adjustment screw was backed off fully and the brake lock mechanism attached to the calliper and fully secured with its two bolts. It was then just a case of attaching the calliper bracket and rubber boots then bolting the calliper to the bike.
Having freed off the pistons at least I know they are free to move and defect free.
