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post #1 of 7 (permalink) Old 06-29-2014, 07:59 PM Thread Starter
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front brake issues

My front brakes are solid when the bike is sitting but when i go down the street i lose pressure when stopping and have to pump the lever a couple times to get pressure back up. went back to house bled the front brake thought maybe air was stuck in lines. was rock solid sitting in driveway kept checking them for about an hour and they were still good drove a block down the road and grabbed they brake and they were soft. HELP don't know what else to do
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post #2 of 7 (permalink) Old 06-29-2014, 08:43 PM
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A few thoughts.

It might possibly be a worn cup seal in the master cylinder. Does the brake lever gradually drift inward while holding for a while?

Do you have any pulsation in the brake lever? If so, then a warped rotor may be pushing the pistons into the bores.

Do you have any fluid residue at the end of the master cylinder?
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post #3 of 7 (permalink) Old 06-29-2014, 09:50 PM Thread Starter
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before I bled them the lever went to the grip and no brakes had to pump the lever a few times while ride and pressure returned. bled the brakes and then took it for a ride and a little down the road grabbed the brakes lever got soft again but was able to stop without pumping the brakes got back to the house got off my bike grabbed the front brake and it is solid again. there is no pulsing that i feel in the lever. I also checked and added fluid to the res and it all look good. I can also apply the brake in driveway and hold it on with it rock solid for about a minute it doesn't budge . ride down the road its spongy
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post #4 of 7 (permalink) Old 06-29-2014, 10:06 PM
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warped/bent rotor. i had the exact same issue when i first got mine. take the rotors off and set them on a flat surface...odds are, one or both of them are bent. my $0.02
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post #5 of 7 (permalink) Old 06-29-2014, 11:09 PM Thread Starter
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thanx ill give it a try
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post #6 of 7 (permalink) Old 07-03-2014, 10:22 PM
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I have a similar thing, do you have OEM brake system? Or after market? Could be the rotors as mentioned but have you bled from the top and not just the bottom? Seems odd but this was suggested to me.


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post #7 of 7 (permalink) Old 07-04-2014, 04:17 AM
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You need to spin the wheel to see if the rotors are warped & pushing the pistons back in the callipers.
Also check to make sure the breather in the Master cylinder is'nt blocked. If its blocked, it can create a vacuum in the hydraulic system, pulling the pistons back in the callipers.
Unlikely I know, but i've seen it happen. Not on our bikes with remote reservoir. But on M/C's with integrated reservoir.
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