'06 ZX636 master cylinder problems?

[BADGRL]

Hey guys,

has anyone ever had any probs with their ninjas in relation to the front master cylinder? I originally bought the bike with no front brakes, bled them and they're sweet but have since gone soft again (over 1 mnth/500kms).

I suspect the very top bleeder valve is ever so slightly letting air into the master cylinder and down into the lines. With the bleeder valve nipped up tight I can still suck air/fluid out but can't blow it back in... thought it may have been a 1 way valve but nah the lines are still getting air in them.

Would replacing just the bleeder valve help? When it's nipped up what seals it off? Is it the valve itself or something inside the m/c?
Any advice would be much appreciated

[SVboy]

I cant answer your questions-but is this karma for swapping your drz!!!

[Wiki Drifter]

Brakes became soft on mine, bled them, replaced the fluids etc, but they went soft again after a few days.
In the end I had to replace the entire master cylinder.

[BADGRL]

I cant answer your questions-but is this karma for swapping your drz!!!

Haha probably, I miss the drz like CRAZY!! Will definately buy another one eventually

[BADGRL]

Brakes became soft on mine, bled them, replaced the fluids etc, but they went soft again after a few days.
In the end I had to replace the entire master cylinder.

Damn that's the wrong answer! lol. Best I start looking for a second hand m/c or rebuild kit :S

[imdying]

If air can get in, fluid will get out. If it's not leaking it should be fine.

[BADGRL]

If air can get in, fluid will get out. If it's not leaking it should be fine.

But that's what has me stumped! It's dry as, not leaking in the slightest... definately air getting down the lines and this is the only suspect valve :S Could it be 'cos other than the reservoir this valve is the 2nd highest point of the brake lines so gravity is stopping fluid from coming up and also sucking air down?? lol

Maybe I just source a second hand m/c and fingers crossed

[FJRider]

But that's what has me stumped! It's dry as, not leaking in the slightest... definately air getting down the lines and this is the only suspect valve :S Could it be 'cos other than the reservoir this valve is the 2nd highest point of the brake lines so gravity is stopping fluid from coming up and also sucking air down?? lol

Maybe I just source a second hand m/c and fingers crossed

Maybe it is the fluid quality that is the issue. When it was last bled ... was it just topped, up or changed. Change the fluid and check/replace seals.

[FJRider]

If air can get in, fluid will get out. If it's not leaking it should be fine.

Not entirely correct ...

http://soarer.ace.net.au/brake_fluid.html

[BADGRL]

Maybe it is the fluid quality that is the issue. When it was last bled ... was it just topped, up or changed. Change the fluid and check/replace seals.

Yeah when I got the bike I was hoping that's all I'd have to do I've completely flushed out the lines and reservoir with high quality fluid and over the month it's nearly back to how they were.

Ooow you say seals, is there one in the m/c itself? I went into Kawasaki and they obviously hadn't come accross this before :S

[FJRider]

Yeah when I got the bike I was hoping that's all I'd have to do I've completely flushed out the lines and reservoir with high quality fluid and over the month it's nearly back to how they were.

Ooow you say seals, is there one in the m/c itself? I went into Kawasaki and they obviously hadn't come accross this before :S

Refer to your workshop manual of your model. Seals will be cheaper than a new unit/system ...

High quality fluid (or expensive/new) ... ???

http://en.wikipedia.org/wiki/Brake_fluid

[BADGRL]

yup some new fluid, I swear by the Castrol Super4 I think it is - goes up to dot5.1 .... *hunts for the manual

[jellywrestler]

if 'air' can get in fluid will be apparent as rememeber it's under a lot of pressure in operation. As for new seals rarely do i fit new seals the majority of the time it's a matter of a careful clean and reinstall. next thing is to check your method of bleeding there's a fine art to some systems to get it right

[ducatilover]

I'm not sure if 5.1 will work in your M/C (synthetics can be fucking horrid to brakes not made for 'em)

I would re-kit your M/C assuming the bore in it is okay.

[Wheeliemonsta]

The problem lies in the bore diameter on the master cylinder which is a 5/8ths (15mm) inch from memory...

If you want to retain the original cylinder the only way you will get a good consistant lever is to have them pressure bleed using a good quality Dot 4 or 5 fluid (as they are ex factory), during this time the rest of the system can be inspected for any further faults such as a bypassing cylinder set etc etc...

The permanent fix is to either have the cylinder line bored to take a 3/4 inch (19mm) cylinder set or replace it with an appropriate Brembo unit which retail for around for $500 dependent on how flash a model you want...

Cheers