removing rear master cylinder piston

Mines stuck big time, although I have kit for rear master, looks like won't get to use it. Does anyone know a way to get this baby moving. Bike had sat for a while in the tropics. If no light shed, will just have to get a new master I guess. ta. Scott J

 

Since you have a kit, you could try soaking it in penetrating oil. Once soaked you could try air pressure to "blow" the piston out. Care should be taken to restrain the piston if this technique is used. The piston can become a projectile and cause injury or damage. If you soak it in penetrating oil you will have to clean the housing with brake clean to ensure that there is no contamination to damage the new seals.

 

Did you manage to get it out?

 

When I encounter a Master Cylinder with seized guts, I have a procedure that I like to use.

I reach behind the Garage Door and pick-up a 31-Ounce Louisville Slugger Baseball Bat.
Then, I step outside and toss the Master Cylinder out in front of me at about forehead height.

Bottom of the ninth, bases loaded, winning run at the plate, no balls, two strikes, looking for the fastball, ... here's the Pitch.
Swing and a drive.
Way back.
Waay baaack!

It's outta here!

 

Get a grease fitting that is close or matches the outlet threads. wrap it with teflon tape,jab on a grease gun and pump. This works everytime for me and no big deal if the fitting leaks a little. Pump away and she will start backing out.

 

After you get the Caliper un-stuck you'll have to do a thorough cleaning.
Remove the Main Seal and clean-out the Brake Seal Channel right down to bare aluminum.

(An old C.B. Antenna and some creative Blacksmithing will make you some fine Tools for scraping the Channel).

That the Caliper Piston was so difficult to get removed means that the Brake Fluid was contaminated.
Flush the Master Cylinder and Lines with Disc Brake Kleen.

Let an undone Brake Line drain the Fluid in the system.
Remove the Master Cylinder Cover and Gasket.
Clean the Inside Cover and Gasket of anything that is not the cover or the gasket.

Evacuate the Master of old Fluid.
Shoot Brake Kleen in Master.
Evacuate. Kleenex dry.
Fill the MC with Brake Kleen and pump it out.
Again.
Once more.

Push some Clean Brake Fluid through the system.
Bleed.
Brakes!

 

I like Rick's idea...... Hit the #$%@ out of it and go find another one. The grease gun method works well also.

 

It just so happens that an automotive grease gun fits the bleeder valve perfectly. Just crack the valve open a bit, and pump.