Hi guys, I'd better get this flag on it's way from the depths of a getting colder south hemisphere so it makes it to Des Moines in time. Who wants to take it? I believe Rob and MrClubike were the last to mention it going to the MOA rally, Sue. PM me an address someone and I'll send it on to it's next adventure.
.I want to replace the 0-ring under the M/C front brake reservoir and maybe while I am trying to figure how to do that right, I could ask about replacing the piston assembly there on that brake while I am at the first job? I am sketchy about doing the latter.
Hi Sue, it's not too hard a job to replace the m/c piston for the first time. You'll need to buy a m/c overhaul kit, the same size as the diameter of the piston, stamped into the underneath of the cast m/c. body. Good job you mention the reservoir o ring, annoyingly they don't come with the overhaul kit so get a couple o rings while you're ordering.
Syringe the brake fluid from the reservoir, put a small hose over the caliper bleed nipple into a jar, loosen the caliper bleed nipple and let the fluid flow out, loosening the brake hose nut at the m/c. Let a bit out while taking the brake handle lever off at the pivot then disconnect the hose and take off the m/c.
To remove the m/c dust boot, there is either a circlip or washer to remove first, my memory fails me sorry. Once the circlip is removed all the parts come out straight forward, there aren't many, just keep them in order.
I reused my original return spring as it was firmer than the rebuild kit spring.
Any corrosion needs to be washed out. Coat the new piston rubbers, o ring and m/c inside barrel in brake fluid before reassembly and remember to firstly put a thick cloth over your tank and guard to protect from fluid drips (beer or brake)Â

Here's a schematic of the handle bar m/c assembly:
https://shop.maxbmw.com/fiche/DiagramsMid/B0003690.png?v=07242017