toasted rear master brake cylinder?

[Guest]

Greetings..

The GS650G I recently acquired was very difficult to push into the garage, due to the rear brake grabbing.. I started working on the rear brakes this evening and well.. Hmm looks like I found out what happens to brake fluid when it's not properly serviced after so many years..

Photos are of the rear master brake cylinder.. and yes, that is ground brown dirt / rust at the bottom.. There is no spring action what so ever, it's seized.. corroded.. beyond repair.. that piston ain't going no where.. Hmm?

Has anything this bad been recoverable or is it best to toss and get a new one?

www.eastcoastphotos.com/gs650g/picture088.jpg

www.eastcoastphotos.com/gs650g/picture089.jpg

[simon kuether]

With brakes , I reckon it's always better to get new stuff .
Having said that , you CAN fix him .
If the bore is pitted , you can get them bored and have a stainless liner fitted for 3 parts of bugger all . A fix him up kit (piston , seals etc) and you're good to go .
Goodluck with it all and let us know how it works out .

Cheers , Simon .

[Seaking]

Thanks Simon.. I've no idea if I could even pull the piston out to check the inside walls. There's nothing to pull on to get the piston out..

If I'm searching for a new master cylinder, what other bike model / year would be compatible with the GS650G version?

Cheers

[JTGS850GL]

Way to many available on ebay in good condition for a decent price to mess with something in that shape IMHO. I'd just pick up a good working unit and be done with it.

[Seaking]

Way to many available on ebay in good condition for a decent price to mess with something in that shape IMHO. I'd just pick up a good working unit and be done with it.

Said and done! Thank you, sir. I had already checked on eBay and currently there doesn't seem to be many available in good shape.. but better than what I have on hand.. part of the fun of this project is hunting for parts.. no? At least the rear caliper came out looking gosh darn decent! The critical sides of the pistons were pristine and smooth, no gunk in there at all.. surprising..

I'm still going to try to free that piston but will most likely end up killing it in the process..

Now to move onto the front calipers.. I think I'm going to encounter the same issues with these.. nice calipers, shyte master cylindre..

[tkent02]

I have all the brake stuff from a 650. Let me know what all you need.

[Seaking]

I have all the brake stuff from a 650. Let me know what all you need.

Awesome!! I'll get to work on the front brake system and let you know soonest how that turns out. But please put aside the rear master brake cylinder system for me I'll be in touch with a grocery list soon...

Many thanks!