Seized Master Cylinder

[Samjp22]

So the rear master cylinder on my 85 250r is seized... does anyone know of any tricks to get it moving again? Or does it have to be drilled out and an aftermarket piston kit bought?

[yaegerb]

Got a compressor? Remove the caliper and snug a bolt in the brake line fitting hole then shoot air into the bleeder hole. Get some rags and cover the caliper so it won't shoot off into space. I usually take a couple dish rags, wrap them around my hand and hold the piston as it is coming out. Make sure to point it away from your face, children and pets ;)

[DohcBikes]

You could try to soak it in cider. Ahhh ha. I'm just bein' serious.

What do you mean drilling?... Do you have access to a sonic cleaner?

[Samjp22]

I'll have to give that a try yaegerb don't know how successful it'll be, when I pulled back the boot there was rusty water and she's pretty black/brown in there and dohc by drilling I mean drilling the piston out with a drill bit lol and has that cider trick worked pretty well for you? Might be worth soaking then blasting with air

[tripledog]

I have heard of people having success removing a stuck piston by installing a grease fitting in the caliper, blocking off the other hole, and pumping grease into the caliper until it displaces the piston. Never tried it myself, but in theory it seems like it would work. But you would have a bit of mess to clean up. I have used the method yaegerb mentioned, and it worked quite well.

[jakep53]

I have heard of people having success removing a stuck piston by installing a grease fitting in the caliper, blocking off the other hole, and pumping grease into the caliper until it displaces the piston. Never tried it myself, but in theory it seems like it would work. But you would have a bit of mess to clean up. I have used the method yaegerb mentioned, and it worked quite well.

This here works every time!!

[Mosh]

http://www.3wheelerworld.com/showthread.php/161391-86-250r-rear-master-cylinder?highlight=grease+gun

[tripledog]

I have heard of people having success removing a stuck piston by installing a grease fitting in the caliper, blocking off the other hole, and pumping grease into the caliper until it displaces the piston. Never tried it myself, but in theory it seems like it would work. But you would have a bit of mess to clean up. I have used the method yaegerb mentioned, and it worked quite well.

^^^
I guess I provided useless info. You stated that you had a seized master cylinder, not a seized caliper. I wish I knew how to read. DOH!

[Samjp22]

haha no worries appreciate all the help!