1978 XS400 Rear Master Cylinder Replacement - any universal MC?

[10Terp]

Hi all -

I have a 1978 XS400 I'm working on restoring to probably flip. It's in beautiful shape, but the owner, for some reason that still baffles me, decided it was a good idea to drain the brake fluid when he stored it a few years ago. It basically renedered the entire brake system in need of a rebuild. I rebuilt the front master cylinder and put an XS650 front caliper on (the piston of the caliper on my bike had pitted to the point of being unusable).

This brings me to the rear master cylinder. It is so rusted and gummed up it won't come apart, and I actually broke the piston inside the master cylinder. I've done some reading on here and I see rebuild kits basically don't exist, and I'm not going to pay $100 for an original master cylinder on ebay that may or may not work. This leads me to finding some sort of universal master cylinder to use as a replacement.

Does anybody have any sort of universal master they've adapted to work for the rear of an XS400? I'm thinking of buying something like this:

https://www.amazon.com/HIAORS-Cylin...=8-6&keywords=125cc+dirt+bike+master+cylinder

Any input would be great. Thank you!

 

[spectra]

Brembo for the win but you need to fabricate a bracket to mount it to......almost the same as you have in the pic.

This is what I did on mine.

 

[10Terp]

Awesome. Do you happen to have a part number? Any idea how much it was?

 

[spectra]

Awesome. Do you happen to have a part number? Any idea how much it was?

I dont the number on it is not the part number. As for price it was a while ago that I did it.

 

[markjs]

IDK if you could make it fit, but I probably have a setup from and xs850, which is a shaft drive bike, so it may not, but afaik, the calipers are same. I have a complete (nearly) 850 I will get pics of if you like, the cylinder is pretty small.

 

[10Terp]

Hey guys, just wanted to check back in and show you all what I wound up doing. I bought an inexpensive master cylinder off of Amazon (https://www.amazon.com/gp/product/B073RZ5Q1D/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1) and had to make a special bracket to mount it. I also had to extend the shaft of the master cylinder using a coupling nut to get it to reach the lever pivot. Here are a few pics.

 

[xschris]

I would be a good idea to replace that 40 year old hose with a new stainless braided style one. It will be far safer and work much better.