ZX6R Noobie

I am having some problems with my front brakes. When the bike is sitting and "cold" the brakes feel and work fine. After the bike is started and warmed up the front brakes FAIL. By fail I mean they have to be pumped a few times before they start to engage. I have bled both sides of the front and there was very very little to no air (now no air after being rebled) and still nothing. Rear works just fine.

Before I order a new front brake master cylinder (only thing I can think of) I wanted to see if y'all know what else it could be? I don't wanna order the part and then find out it could be 100 different things and I bought the wrong thing.

I was told it could be warped rotors too?

Any help is appreciated.

MonsterZX

Ok working of slight knowledge (recently learned) Pick up a vacuum bleeder will save you that headache if there is ANY air in the line or caliber. Also Id assume if it was a warped rotor it would not need pumping. The break would just kind of "pulse" pick up a $30ish vacuum bleeder or borrow one. just my 2 cents

ZX6R Noobie

The guy at Autozone also recommended a vacuum bleeder is the pump bleeder didn't work.

Would even the slightest bit of air cause this problem? Sorry if that sounds really dumb >.>

Alex Gold

Yes, especially if you have braided lines

ZX6R Noobie

They are not braided they are just the stock lines.

Ok, a vacuum bleeder it is! I didn't know if even the slightest bit of air would cause this, I guess I had it in my head "no way just a lil air could do this, has to be something more!" lol

MonsterZX

there could be more air than you think stuck in the brake caliper its self

ZX6R Noobie

Y'all strike again on this forum! Super fast help and so much knowledge.

Y'all are simply amazing! <3<3<3

MonsterZX

Let us know if that solved it. I know we had an issue with my buddies brake and that was the fix. We fucked with that bike for a while till another friend brought his bleeder. So happy to pass it along. nothing more frustrating then a bike not working properly.

ZX6R Noobie

It is very frustrating lol. I bought just a lil bottle one man bleeder from autozone and it had a lil air in the lines but it seemed to have got it all. When the bike was sitting brakes worked fine, fired it up let it warm up to ride and they needed pumped to engage :/

I figured it was a much bigger problem lol.

Gonna head out in a few and pick the vacuum bleeder up, maybe endure the cold and try and fix it today.

I'll let ya know!

MonsterZX

alright man good luck hope it was that simple

NatBrown

It could very well be warped rotors too. Although, you will feel pulsation in the brake lever and in the way the bike stops. As the warp rotors move past the pads, the rotor will push the brake pad away and the piston back into the caliper. When you try to brake, you have to pump in order to move the pad/piston back out.

rattyzx6

What bike is it. if you have stock lines and you ride a 10 year old bike your hoses will be expanding when hot. Feel the hoses when you put the brake on.

It could be an air lock as has been said above.

ZX6R Noobie

o sorry, the bike is a 2000

oldninjadude

First off, Have you had the the bike on stands, & spun the front wheel?
Is it dragging?
You should check this, If there's no drag, Then its a pressure problem.
Could be the master, could be in the lines or fittings.
You should look closely at every inch of the system for tiny fluid leeks.
& of course you want to bleed the system, If your not getting air bubbles?
The master is proly bad.

But you first need to do as I said & check for to much drag, To much will overheat the rotors & cause fade, & lead to warped rotors

trackdayhero

To add to that, and I am not sure if this is an issue on the Ninja but I do know this happens on dirt bikes all the time, is that if you have any water at all in your system (via condensation or otherwise) and you are using your brakes heavily the temps can get hot enough to boil the water which of course creates air bubbles and the brakes will not work. When the brakes cool the vapor turns back into water and the brakes will then work again. If you haven't changed out your fluid you might want to do that in addition to a good bleeding with the vacuum bleeder system to make sure there is no contamination.