Hi again (shouldn't leave your bike sitting) now the front brake lever won't pump up pressure. I haven't pulled it apart yet. Do I just strip it down or is there a simpler fix?

If there is any fluid leaking out you probably need a kit to fix it but try bleeding the system first. I had air get into the system on the K100 once and never figured out how.

+1 that... but if its leaking around the base of the reservoir it'll just be the o-ring on the base. Cheap and easy to replace.

Cheap and easy, unless the PO never flushed the fluid like on my K100. The taper where the o-ring seats was corroded so it leaked even after a thorough clean up... replacement of the hydraulic portion and reservoir where my only options.

I read somewhere that once they start to corrode they've had it... the corrosion will always return. Fortunately, when I pulled mine apart to replace the o-ring, it was in ok condition.

about to do mine again twb

the refurb I did a few years ago seemed to seal ok ...but I have noticed that it is leaking from the same area that you mention
fortunately this time I have an dremel type tool that can resurface the inner seal area / core of the reservoir metal work
its the pitting around the seal area I see as the issue
ill give it a try at least and report my findings

meanwhile I'm onto a hopeful solution to the core of the master cylinder piston- bore that might be a good recommendation instead of throwing $200 aussie sheckles away to the dealers for a new master cylinder

hope you find a solution mate
cheers

Chaz, mine was literally flaking into bits, even carefully sculping it into some kind of funnel didn't help, and I knew it was a long shot when I fitted back up and went to bleed the brakes. It's not gushing, mind, but does set a bead of brake fluid within a coupla hours. My solution was to ask Mark and Dana at Vallantine's, a Seattle workshop, whilst delivering parts to them the other morning, whether in their pile of scrap upstairs they had a spare unit laying about. They did, and as we have a friendly relationship, gave the crusty old piece of kit to me at no cost! Praise be! Thank you. The reservoir looks like new, the innards acceptable, but I'll chuck a seal/piston kit into it and we should be laughing. I too don't wish to part with too much dosh on this project, though she's coming up pretty clean after a few essentials and a bit of a scrub up. The K100 inches closer to the road, at last.

Wish I'd known in February that you needed a MC as I've got my clean, useable RS original in my shed in Beenleigh. Doh!

Hello again well I pulled the master cylinder apart and cleaned it and when I test it, It seams to pump and suck any ideas, it was not leaking so that's not a problem.

Check that both holes from the resevoir to the cylinder are open, one is very obvious and the other is very small and can be overlooked easily. It is about 0.5mm in diameter and is just forward (away from the lever) of the larger hole.

A touch of Phosphoric Acid usually stops the dreaded white worm in Aluminium.

Thanks as soon as I get home I'll have a look for an extra hole I only noticed one the other is probably blocked I'll be home Tuesday