TOPIC:

I finally got the front brakes on my KZ650C working properly. After reading everyting I could find here and elsewhere, including some car forums, and trying several different methods, I finally have a nice, firm brake lever.

Here's the things I did that worked. I disassembled the entire system and cleaned out all the crud and dirty fluid. I had to use hydraulic pressure to get the pistons out of the calipers. 90 PSI of compressed air wouldn't move them. I greased the sliders which made a HUGE difference. The sliders seemed almost frozen before, and pushing the bike around was very difficult. I had always thought this was normal. Now, I can move the caliper around with one finger, and pushing the bike around the garage has never been easier. The brakes also used to squeal horribly while being pushed around, but that's gone too. After reassembly and bleeding using the traditional method used on cars, my lever was mushy. I couldn't two-finger brake any more. The lever would bottom out on my other two fingers, but it wouldn't bottom out on the grip so I still had brakes so long as I used four fingers. I rode it for a couple of weeks hoping that any air would work it's way up and out through the master cylinder. No change after two weeks of riding. I tried several other methods, but what finally worked was forcing fluid from the calipers back up through the master cylinder by pushing the piston back into the calipers. While pressing the pistons into the caliper with a C-clamp, I had a helper tap on the master cylinder while moving the MC around (tilting it back & forth) to dislodge bubbles. Then she worked the brake lever a few times to push the piston out a little and we repeated the process two more times. Result: Solid, two-finger braking again. I've had this bike over 20 years and I don't think that the front brakes have ever been this good. Now on to the rear brakes!

Congrads. Different working bottom to top but ,hey, if it works!

del

I was thinking of making a contraption with like a meat syringe purchased from a kitchen supply. Hooking some clear tubing to it and connecting itto the caliper bleeder and pushing fluids in from there also.
I cant seem to get and pressure from my master whatoever so I am tearing into the front brakes in the next couple days as time permits.

I had the same problem. Turned out to be crud in the master cylinder. Once I got it cleaned out it started working fine.

From reading your post, I realize that one of my sliders is rusty... and I need to get it moving freely to have brakes that work. You put a lot of detail in your post, and I say thanks!

bemoore wrote:

I had the same problem. Turned out to be crud in the master cylinder. Once I got it cleaned out it started working fine.

dont stop at freeing rusted brake parts up, the brakes are the most valued part for a motorcycle above tires, you life depends on the brakes & good tires.

if you have any rust in the brakes whatsoever, pull the whole system (front or rear) and rebuild them (letting the bike sit) members here can & will help you get non rusted brake cyclinders & caliper pistons.

if your master cylinder is crusty I garantee that your calipers probably have pitted rust holes on the caliper piston & its not worth dying for to go out riding with them like that.

Just my .02 cents.