HOW TO CLEAN THE PISTONS:
Required items: Brake cleaner, brake grease, copper ease, brick banding (the plastic strip thing that goes round cartons), face mask, gloves, cup of tea.
Take the callipers off as per Haines Manual.
Take brake pads out
Pump brake lever to push pistons outwards (* WARNING* be careful as they will pop out if you pump too far) You will see baked on brake dust to the surface of the piston, make sure you can see it all.
Spray with brake cleaner
Use brick banding, wrap round piston, and gently remove the build up, you will be able to push the pistons in with your fingers if they are clean. The pistons are brass I think, and they look nice when clean.
Once clean rub brake grease onto sides of the piston only (*WARNING* get the right type of grease from local bike dealer)
Dab a little copper ease onto the back of the pad only
Re assemble
DO NOT breather in the brake dust, it’s deadly, wear your mums gloves, and before you go for a ride pump the lever to make sure the pads bed in again.
Why clean the pistons? Because there is a little rubber seal that the build up of brake dust will trap itself behind if you replace with new pads and do not clean the pistons. The new pads push the piston further into the calliper, pushing the build up behind the seal – Outcome is that this will make the brakes less effective with new pads as it may seize a piston.
Optional – the back brakes on the 748 are there as a foot rest only, they don’t really work
you can service them if you wish.
Oh take you time, you have all day.