'81 GS550T front master cylinder - rebuild kit options?

[sacruickshank]

Maybe this topic is covered in a thread somewhere, but does anyone know a good source for a front master cylinder rebuild kit for an '81 GS550T? It's also used on the 79-80 550L, the model with the cylindrical reservoir rather than rectangular, I can't get pressure on mine no matter how much bleeding occurs. I suspect the old m/c rubber is letting air into the system.

if they are unobtainium, are there any swapping options from other models? I have kits for Honda GL500 and CB350 stashed away from other projects, which both seem close but not exactly the same. Strangely, the circlip for these fits inside the bore and is smaller than most other kits I've seen.

Pic below for reference if needed.

 

[Nessism]

Parts for our GS's are drying up. I'd get a late model 14mm master off ebay. You can even get new ones for cheap.

 

[sacruickshank]

Parts for our GS's are drying up. I'd get a late model 14mm master off ebay. You can even get new ones for cheap.

It would need to have a similar front brake indicator switch ... which BTW I just rebuilt using hand cut copper sheeting and a spring from a pen.

There's a swap meet coming up next weekend, so that might provide an option beyond ebay

 

[Nessism]

Brake switches are very simple devices. Basically just a pass through wire when the brake is connected. You can easily adapt some other master to your GS.

 

[sacruickshank]

UPDATE - For aspiring Dr. Frankensteins, the internal rubber bits from the GL500 front rebuild kit that I have on hand are extremely close to the GS rubber bits and the relative dimensions between the two plungers are the same. The external rubber grommet that fits around the is too small, so I don't have a solution for that yet.