Dual disc conversion - 650B

Mine has one disc - on the left; how hard would it be to just bolt on another disc on the right + caliper and hose? I know some other 650's had dual discs - mine has a mount on the right fork leg, and a cover on the right side that may be over the disc holes (I'll have to check).

Also, can the older ('77) style round master cylinder support 2 brakes?

Under that dust cover is the mounting points for another disc. To make it headache free try to source a system from a C model of about the same vintage. The rotors would be the same thickness and the calipers will bolt right up. And to answer the MC question, no. You wouldn't have enough bore on the MC to effectively work both calipers. If you want a dual disc set up keep your eyes open for a complete system from a C model, including the splitter from the MC down to the calipers. Swap everything in and bleed the system and you're good to go.

Or use an MC off a newer bike that has dual front discs. Unless you want to keep the stock look, in which case start watching ebay.

Yeah and get a rebuild kit. The MC that came with my set is so crap. It stops ok, but I know it could do much better, so I'm gonna get a new cheap-o 14mm MC off ebay at some point, since I can't get mine apart to rebuild it in any case..

KawiConvert wrote:

Or use an MC off a newer bike that has dual front discs. Unless you want to keep the stock look, in which case start watching ebay.

The newer MC would work, but you'll still need to get the splitter for the brake line. While you're replacing all these components it'd be a great time to upgrade to braided steel lines too.

anarki650 wrote:

KawiConvert wrote:

Or use an MC off a newer bike that has dual front discs. Unless you want to keep the stock look, in which case start watching ebay.

The newer MC would work, but you'll still need to get the splitter for the brake line. While you're replacing all these components it'd be a great time to upgrade to braided steel lines too.

If you're upgrading your brake lines anyway... get two lines the same length and attach them both to the master cylinder with a double banjo bolt. This way no spliter needed. This was a trendy "upgrade" on some late model crotch rockets. I think some yammy's came like it. To be honest I don't know if its better, but if you don't have a splitter...

The '77 KZ650B and KZ650C used different thickness rotors, different master cylinders (both were round), different fork legs, and the KZ650C had cast wheels (with calipers behind the fork legs) so I don't know how difficult it would be to adapt dual disks to the wire wheels. You could put the whole front end from a KZ650C on a "B" model, but then the rear wheel wouldn't match. Changing the rear to disk brake would be another challenge as the swing arm is different and you'd need to mount the rear master cylinder on the frame. Ed