Topic: What master cylinder is this?

[Scott S]

 I'm working on restoring a set of Pentagram wheels for an XS650 project. 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.

[martin99]

Take a look at the exploded view on this eBay item. Looks pretty close to me.

http://www.ebay.co.uk/itm/HURST-AIRHEART-NOS-Master-Cylinder-Diaphragm-Vintage-Go-Kart-Cart-ATV-6x6-UTV-/191516960007?hash=item2c974ce507

[Scott S]

 Yup....I had kinda figured it out since I posted. Just trying to make sense of their parts numbering system now to see if I can use the $9.99 rebuild kit instead of the $67.99 kit!

[754]

Looks a bit like Grimeca..is there a plate covering the side? Where the name may be...
If its Hurst Airhart its second generation.. What caliper is it hooked to?

[Scott S]

 I haven't removed the plate yet, but looking at parts diagrams, I'm 99% sure it's a Hurst.
 I'm a sucker for vintage wheels and I'm restoring a set of Pentagram's. They were dealer accessories that were built (I believe) by Shelby Dowd. The set I have was installed on an XS500, so I have some bearings and spacers to swap.



 The caliper is a Yamaha front caliper held on by this bracket. It uses that axle and the drum brake torque arm.



 You can see it in the lower wheel in this pic, too (grabbed from the interwebs).