Make it stop!

So I've been having front brake problems (06 yz450f). There is a lot of lever play before the brake starts to engage. My brother has an 05 yz250 and his front brake feels awesome and engages right away, no play in the lever at all. There is about 1/2 to 3/4 inch of play in the lever before it starts to engage. I have completely flushed the fluid and that didn't work. Then I rebuilt the front master cylinder, any idea what it could be?

I would start by bleeding it quite well. It sounds like there is air in the line. Have you tried to back bleed it?

back bleed for the win

back bleed for the win

 

OK, everyone says this.  In theory, it is a fantastic idea.  But I want to know, how many of you advocating this have actually tried it:confused:   It is messy, yes I've tried it a few times and have always ended up bleeding the traditional way with great success. 

 

Be honest, who has done this without making a mess? :thinking:

Backbleeding for the win X2

It works and quick too. Not very messy if, pause and look, etc.

Edited by DEMI

Backbleeding for the win X2

It works and quick too. Not very messy if, pause and look, etc.

 

Not VERY Messy?  LOL, it is a bigger mess than the traditional way no matter what you do.  The old fashioned way is ZERO mess, and yes it does work. ;)

Reverse bleeding brakes is easy with the right tools.

I do it all the time on industrial vehicles that I work on professialy.

I have an oil squirt bottle from HF and some various sized clear hoses.

Also, the OP's problem could be from a failing brake hose with a weak spot.

Edited by HappyAndy

You're doing it wrong!! What's the old way? Gravity and pumping the lever... if you are retired then that way is an option...lol.

You're doing it wrong!! What's the old way? Gravity and pumping the lever... if you are retired then that way is an option...lol.

 

A few months ago I rebuilt the front caliper on my bike.  Bleeding and completely purging the system took less than 15 minutes doing it the old fashioned way.  And there was zero mess and no air in the line. ;)

A few months ago I rebuilt the front caliper on my bike. Bleeding and completely purging the system took less than 15 minutes doing it the old fashioned way. And there was zero mess and no air in the line. ;)

Evidently it is your way or the wrong way, so here's your pat on the back.

Evidently it is your way or the wrong way, so here's your pat on the back.

Thank you. :)

As I mentioned earlier, I think a lot of folks have heard about back bleeding, so they follow the herd and advocate it without actually trying it.

I have a feeling you will argue for the sake of arguing, don't need a pissing contest with you, so have a great weekend.

To the OP - Did you ever NOT have the free play?

So how exactly do you back bleed it

To the OP - Did you ever NOT have the free play?

I just purchased it about a month ago so I've felt it as long as I've owned it

OK, everyone says this. In theory, it is a fantastic idea. But I want to know, how many of you advocating this have actually tried it? :confused: It is messy, yes I've tried it a few times and have always ended up bleeding the traditional way with great success.

Be honest, who has done this without making a mess? :thinking:

I've back bled a few ktm clutches and the front brake on my cr250. It can be messy but I'm usually expecting that so no worries. Just have to place rags where needed. Edit: I use a 60cc luer lock syringe and some carb vent hose I had laying around. Works ok. Edited by bodge

I gravity bleed them.  Works perfectly well.  There's one glitch regardless of the method, and that is that there is a big wide spot for a bubble to take up lodging right at the banjo bolt at the master cylinder.  That bubble can usually be "tickled" out into the reservoir by working the lever just a couple MM at a time. 

Does it feel spongy ALL the time, or just when you're on the trail and moving? If your rotor is bent, it will push the pistons back in the caliper a little when the high spot of the rotor passes through. This will cause excess travel in the lever, although usually it'll pump out quickly. If your problem is all the time, even when still, then ignore this.

Does it feel spongy ALL the time, or just when you're on the trail and moving? If your rotor is bent, it will push the pistons back in the caliper a little when the high spot of the rotor passes through. This will cause excess travel in the lever, although usually it'll pump out quickly. If your problem is all the time, even when still, then ignore this.

All the time, it was spongy before I rebuilt the master cylinder, now it still has play in the lever but after the short amount of play, the lever is stiff.

I gravity bleed them.  Works perfectly well.  There's one glitch regardless of the method, and that is that there is a big wide spot for a bubble to take up lodging right at the banjo bolt at the master cylinder.  That bubble can usually be "tickled" out into the reservoir by working the lever just a couple MM at a time. 

 

That's a good trick.  I also like to get the lever as firm as I can get it, then zip-tie the lever to the bars at least overnight to help coax any additional tiny air bubbles out.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now