unusual braking issue

The front brake on my 1982 Kawasaki 750 CSR M1 is doing something unusual. In fact, a mechanic of 30+ years says he's never seen this before. If I am too gentle when pulling the brake lever, it softly pulls in to the hand grip and doesn't apply the brake. If I tug just a little more firmly, it works just like a normal brake.. What's going on here?

Post edited by: Shaolinwind, at: 2007/05/08 21:05

Master cylinder needs a rebuild,or You need to bleed the whole brake system.

what sandy said;)

Hmmm...
Not sure I'd trust a mechanic who'd never seen that before. Your master cylinder seal leaks just a little. So when you pull hard, it doesn't leak as much as your piston travel displaces, so you have hydraulic pressure going to your brake cylinder. But when you pull lightly, you're only asking the piston to displace as much hydraulic fluid as your leaking seal allows to pass. No extra pressure for the brake. The warning for you is this: you're just one good hard squeeze away from your master cylinder seal completely giving up, and then it won't matter how much you squeeze, there won't be any brake. Get it rebuilt NOW. Your bike has given you all the warning you will get.

pstrbrc wrote:

Hmmm...
Not sure I'd trust a mechanic who'd never seen that before. Your master cylinder seal leaks just a little. So when you pull hard, it doesn't leak as much as your piston travel displaces, so you have hydraulic pressure going to your brake cylinder. But when you pull lightly, you're only asking the piston to displace as much hydraulic fluid as your leaking seal allows to pass. No extra pressure for the brake. The warning for you is this: you're just one good hard squeeze away from your master cylinder seal completely giving up, and then it won't matter how much you squeeze, there won't be any brake. Get it rebuilt NOW. Your bike has given you all the warning you will get.

EXACTLY!

I thought about that too,after I re-read the post a while later...what Mechanic wouldn't recognize those symptoms??:huh:

Dont dodle on this 1 pal.This is not safe.Please be carefull.

Post edited by: mark1122, at: 2007/05/09 01:45