Front brake issues - Honda RC51 Forum : RC51 Motorcycle Forums
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post #1 of 14 (permalink) Old 02-24-2016, 12:48 PM Thread Starter
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Front brake issues

Gents,
Hope everyone is well and having a great day. I need a little help and was wondering if I could get some assistance. About a week and half ago I was on my home from school when I applied my brakes and damn near had to pull it to the throttle to engage. So I got home, checked for leaks nothing. I grabbed the brakes (sitting) and they were normal. The next day I take it out and same thing, brake lever is damn near on the throttle.

So, I figured it was my pads. I ordered new pads, new levers (PSR clutch and brake), and spiegler lines (hell why not eh). Threw them on yesterday and this morning and took it for a spin. Brake lever still not where it used to be. So I figured hey, maybe some air is in the lines so screw it, take it to the dealer and let them get the air out...it'll be worth it. So I did that. On my way home...same damn thing. If I pump my front brakes after a few it brakes "normal" like photo #1. I included three pics. First pic (no gloves) is the position my brake lever has activated since I got the bike and up until last week. Second and third pic (with gloves on) is where it is now to activate braking (close to the throttle). Deal said the reason it's coming so close is because my left rotor is slightly bent.

So my question is what's the deal? Is this my new normal or did the dealer not get all the air out? Thanks for any comments or feedback in advance.
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post #2 of 14 (permalink) Old 02-24-2016, 12:57 PM
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put the stock lever back on and try it, if the pattern lever is holding the piston so it can't top itself up through the port you will have problems
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post #3 of 14 (permalink) Old 02-24-2016, 03:57 PM Thread Starter
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Dansp1,
I don't believe it's the lever as it was doing the same thing with the stock lever. Sitting, they are nice and firm as they were about two weeks ago. Once start riding And then apply the front brake they feel soft and the lever comes damn near on the throttle. I thought it was air but after I took it to the dealer and they bleed it, it’s still soft.

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post #4 of 14 (permalink) Old 02-24-2016, 04:15 PM
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Garage
Maybe the master cylinder seals.
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post #5 of 14 (permalink) Old 02-24-2016, 04:54 PM
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take the lever off, try to replace it, when you put it back on do you have to push the piston in to get the lever on?
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post #6 of 14 (permalink) Old 02-24-2016, 09:03 PM Thread Starter
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Dan, I will give it a try on the morning. What am looking for? I'm also going to buy me a bleeder and do it myself again.
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post #7 of 14 (permalink) Old 02-25-2016, 02:24 AM
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As I said the piston in the m/c must be able to come out all the way, if it is held in by the lever the port that opens to keep the system topped up can remain closed
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post #8 of 14 (permalink) Old 02-25-2016, 12:47 PM
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Possibly the disc that is warped. If you pump up the brakes and leave it overnight, is it ok in the morning? If so. It's not air. If it's gone soft again and requires pumping you have an air in the system problem.
If the problem occurs after riding a distance the warped disc is pushing the piston back slightly and on your initial brake application you are taking up the slack so to speak. In which case you need to replace the warped disc.
Hope that helps.

Rob
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post #9 of 14 (permalink) Old 02-25-2016, 01:58 PM
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Regardless get rid of that OEM master cylinder and put a Brembo unit on it either a forged 19x18 or the RCS19. You will be very glad you did!

These trick pinch bolt reservoir kits are very popular with RC guys as well

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post #10 of 14 (permalink) Old 02-25-2016, 02:05 PM
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Ate brake fluid?
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