What master cylinder is this?

[scott s]

I'm working on restoring a set of Pentagram wheels. They came off an XS500 and that bike seems to have been converted from drum to disc.
I have all the stuff to swap in a disc brake swing arm, but the more I look at this stuff, the more it appears I could use it with my drum brake swing arm with very little effort.

What master cylinder is this? Are rebuild kits available? What is the green thing/stuff that seems to have come loose inside the plunger mechanism? The only markings on it are "7/8", which I guess means it has a 7/8" bore.

If I can make this work, I think I will. Simply for the "weird" factor, if nothing else. Plus, I can keep the drum brake swing arm set up if I ever want to switch back.

 

[fredintoon]

Hi Scott,
to be clear, you are putting the Pentagram wheels on your XS650 which has a drum rear brake & swingarm?
You will most likely have to weld a new brake torque arm lug onto the XS650's drum
brake swingarm to suit the Pentagram wheel's brake caliper torque stay.
Leave the XS650's drum brake torque arm lug in place so you can easily swap back to stock if you want to.

 

[scott s]

Nope, I got all that figured out. The Pentagrams came with a rear caliper and a special bracket that uses the brake drum torque arm.

I'll eventually make a thread showing the restoration and fitment of the wheels and brakes. But first, I need ti I.D. this master cylinder.

 

[izatso]

I believe it to be an early Hurst....

 

[scott s]

Hmmm....the parts do look similar.

http://www.ebay.com/itm/VINTAGE-NOS...MPH-/261818137812?hash=item3cf593bcd4&vxp=mtr

What's the green thing in the spring?

 

[scott s]

You guys are awesome....look at this:

http://www.ebay.com/itm/go-kart-par...pt=Race_Car_Parts&hash=item3aa17c6768&vxp=mtr

 

[izatso]

It's a valving plunger, the ones in the aluminum ones I have, these are white, but it normally has either 2 or 4 angled fluid holes to determine the amount of fluid pressure to the brakes.....some Harley Davidsons used master cylinders similar to this and you might be able to find your rebuild kit from a Harley aftermarket supplier.

 

[scott s]

There are a few kits on eBay. I'm just trying to decipher their numbering system so I can see if I can use the $9.99 kit instead of the $67.99 kit!