1977 KZ650B1 Master cylinder question. Just checking with the experts

I have a single disk system. No desire to retrofit a dual. Replacing/refurbing the entire front system. I see K1 has a MC for a dual system. (Front Double Disk 5/8" M/C Complete Assembly - for 7/8 inch 'bars). I sent an email to K1 technical asking them if this specific MC will fit my single disc system. They responded that model will fit a "the 77-79 KZ650 models". Just checking with anyone here that may have used this MC on a single disc system. Thank you for your assistance as always!!

Single disc systems typically take a 14mm master cylinder. A 5/8" bore master on a single disc bike will result in a very firm lever that takes a lot of hand force compared to a 14mm master.

Thank you Sir. I have found a good retailer on Ebay that has a few OEM MCs that have been refurbed for about the same price. Appreciate the great response!

Some of the 70s KZ650s had a dual disk Fr brake, so that's probably why they say it's suitable for your bike. It's a common mistake lumping too many models together for the model fitment. I see it all the time on EB & elsewhere.

The stock master cylinder on my motorcycle is embossed with 1/2 (1/2" = 12.5mm) (1981 KZ650 w single disk Fr br).
I installed a good used Fr brake mc from a Honda CBR500. For the brake light wiring I got the Fr br wire lead from a KZ1000P police bike.

Best upgrade to single disc is braided hoses. Makes a massive difference.

Yep. I plan on going with Stainless lines. Any recommendations on who to get them from?

HEL braided lines are about teh best you can get. Assuming your in the US so below are your dealers.

HEL Performance Motorcycle East Coast
Powersports KC
PO BOX 3684
Shawnee
KS 66203
United States

us.helperformance.com

sales@helperformance.us

913-730-7500

Motorcycle

HEL Performance Motorcycle West Coast
ND Customz
19771 Hirsch Ct
Anderson
CA 96007
United States

usa.helperformance.com

ndcustomz@hotmail.com

530-945-2564

Also these

galferusa.com/products/lines

CycleBrakes.com sells the Galfer stuff. I installed Goodridge lines & fittings from Z1Enterprises.com. There's a little extra work to install the fittings, but it's very easy & I've never had a leak. One benefit is that you can change the fitting at the master cylinder some time in the future if need be in case you make a change. If you go the Goodridge route, each fitting adds slightly less than an inch (~24mm). so if the needed eye-to-eye measurement is 19", get a 17 or 18 inch line.

Confirmed the stock master bore is 14mm. For brake lines I like Earl's parts. Made in USA and lots of options to match your particular bike, mods and all. Check my rebuild thread for a photo tutorial.

www.anplumbing.com/

Is that chart from the KZ650 manual? The Z1 FSM has a similar chart with the same numbers for the single disk.

martin_csr wrote: Is that chart from the KZ650 manual? The Z1 manual has a similar chart with the same numbers for the single disk.

Yes, KZ650 factory manual.