Bleeding brakes

So iv rebuilt my calipers I can't get anymore air out of the system but I still have no brakes, the Pistons move out and return but don't seem to move out and stay out to keep moving the pads along .




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[Craig380]

Is the brake lever coming all the way back to the twistgrip? If so, there's still air in it somewhere.

Best thing to do is to put the bike on its sidestand, with the handlebars turned full left lock, and leave it alone overnight. This way any air can rise to the master cylinder and into the fluid reservoir. Then you should be able to pump the lever a couple of times and have brakes.

Yeah iv done that , hopefully it will work iv broken bleed nipples so using banjo bleeders I'm sure the calipers are OK as I bled hem with the nipples straight up . It must be at the master cylinder .


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[Nutsinatin]

Might well be the master cylinder, build up pressure, crack the m/c banjo open (using a cloth to catch any fluid), close and repeat until pressure returns. It's where I've had the air trapped last two times this year.

[andrewsmith]

Also give the rubber hose connecting the fluid reservoir a good squeeze as air does get trapped there

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There is no reservoir, it's a naked bike


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[Red Herring]

Originally Posted by Craig380

Is the brake lever coming all the way back to the twistgrip? If so, there's still air in it somewhere.

Not necessarily so. Sometimes when you have just rebuilt callipers as the OP says he has the pistons move so freely that the suction caused by the master cylinder returning is enough to pull them back in, which is what the OP says he can also see happening.

The easiest way I've found to get round this is to rattle the brake lever back and forth really quickly with your hand. Don't come all the way back to the bars, all you are trying to do is get a little more fluid into the active side of the plunger before the suction has time to move the pistons. It should only take a few seconds. Once you have some pressure then give it a really good squeeze to seat the piston seals, then there should be enough friction to allow you to bleed the brakes conventionally.

[NedSVS]

When you fit banjo bleeders you may have to remove the calliper and adjust the angle of it so the banjo bolt is at the highest point - because the banjo drilling often enters well below the highest point of the cylinder and therefore traps some air.

Originally Posted by damienga15de

There is no reservoir, it's a naked bike


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I'm pretty sure there's still a reservoir, it's integral to a fluid based braking system.

The reservoir is the black box that sits next to your right hand grip (throttle)