Hum drum stopping

My new to me kz650 F1 is providing me with some unimpressive stopping power. There's plenty of pad on the (I assume) stockers and i've bled it for good measure with perhaps some improvement. The first 1/4 lever action provides decent stopping but thereafter even great amounts of squeeze get about the same response. I know a similar problem was just posted with a 750, though my problem doesn't seem as severe. Just wanted to see what ya'll thought I should do next before I dig into the MC or order a braided brake line. If the master is bypassing internally does this mean a bad piston?

Good to be here

Just to be clear - the brakes don't actually feel spongy, lever feel is pretty good, its just not translating into good stopping power which is why I'm perplexed. If the lever bottomed out or just pulled in too easily I'd assume air in the system and keep bleeding but it feels about right.

Might want to consider your pads. Different pads (semi metallic, organic, asbestos free, etc) can give differtent "feel" and "stopping" power. Don't remember what's on my single disc F1 but it stops real hard, even with two fingers.

Well if the piston was bypassing, you'd get no lever at all, or it would slowly bleed down while you're trying to stop.
If it was me, I'd take the pads out and see if they're glazed, then sand them on some 80 grit paper, and try them out.
If that didn't work, I'd ask one of these KZ gurus, if maybe somebody installed an MC on your bike from another bike that had two discs. Different piston sizes.

You may have oil or something on the rotors. I would clean with brake cleaner and deglaze the rotor also.

cmmman wrote:

You may have oil or something on the rotors. I would clean with brake cleaner and deglaze the rotor also.

+1, cmmman.
Try cleaning first. The front brake should be able to lock up your wheel, if you grab a handful.

Yes, cleaning too, but if you have some kind of fluid on your front pads, it would almost have to be brake fluid, in which case, you'll need more than we've suggested so far.
Rebuild kit, new lines, copper washers etc.
I just consider the front brake THE most important system on the bike...

yep there was fluid on the pads and in the caliper and on the rotor. Anybody know where to get a good rebuild kit?

Call Z1 Enterprises at 315-926-5054, very nice people for sure. They can set you up with anything you need..

A suggestion would be to replace all of the front brake lines as they age and will swell/expand every time the brakes are applied giving you that great underwellming responce.

Two places I can think of for brake lines:
www.bikebandit.com
www.oldbikebarn.com