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Brake Not Building Pressure

Discussion in 'General Biking Chat' started by Juho Sirviö, Jul 14, 2020.

  1. Juho Sirviö

    Juho Sirviö New Member

    Location:
    Finland
    Current Bike (Optional):
    Yamaha YZFR 125 2008
    License Currently Held:
    Other
    Apparently I just can't go a month without some sort of problem.

    Ight so ummm not sure if this is important but after my crash my front brake has been doing this like a hissing sound everytime I press it. It made that sound only if I was moving and applied brake. Also the brake just started feeling like ummm you know how your brakes feel when they need to be bled. Like I had quite alot of free move in the lever and I sometimes I could pull the lever all the way back so that it would touch my throttle. But then sometimes it wouldn't go that far but still had a bit of free play. So I tried to bleed the front brake (rly wish I wouldn't) and ummm well I don't know if I messed something up but now the brake isn't making any pressure. Yes there is fluid and it's the right fluid (dot 4). There is fluid coming out of the bleeder-thing in the caliber but no air bubbles (or atleast I think so cuz I'm not seeing any). I'm not really sure how quickly the fluid should be coming out of the bleeder-thing (and yes I have a plastic see-through-hose attached) but it's coming and empyting my fluidreservoir.

    I'm not sure if there still is air in the brakelines or if I really messed up.
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  3. NorthCust

    NorthCust Active Member

    Home Page:
    Current Bike (Optional):
    2008 Yamaha R125
    License Currently Held:
    UK Full Bike
    I've had this happen too and I thought there was something wrong with the lever, or god knows what. no it was just either not sealing somewhere on one of the banjo/rings or there was an air bubble....and you've spent the whole afternoon half soaked in brake fluid and for what?? arg.

    However hissing sound probably isn't great, could do with tracking that down lol.

    What has worked for me a few times in those problematic situations is "reverse bleeding". So you use a large syringe and push the fluid in from the bottom up and seems to dislodge bubbles sometimes. There's some good tutorials on youtube.

    Also "bleeding it on the bench" is an option if it's really tricky...so take the brake components off the bike, get the brake action sorted off the bike where you can tip the caliper and hoses around to get rid of all the bubbles. I think they do this a lot with stuff like the triple caliper setups on the back of stunt bikes bc the bleed nipples point in all directions so you can't actually bleed it on the bike.

    you can sometimes also bleed a specific joint/banjo, not just the assigned bleed nipple. Just like you can introduce air into the system that way, on occasion it can work to remove it.

    pushing the pistons fully back (retracted) can also remove air bubbles from behind them

    hate working on brakes, always this same cycle of self-doubt and then it magically works. meh :(
  4. Juho Sirviö

    Juho Sirviö New Member

    Location:
    Finland
    Current Bike (Optional):
    Yamaha YZFR 125 2008
    License Currently Held:
    Other
    You're really every R125 owner's savior. I might try the syringe thing today and see if that helps. Also now that I remeber, few of the times that I've added brakefluid, the fluidreservoir has sucked in air while removing the cap/cover or atleast I think so and other times it doesn't
    NorthCust likes this.
  5. NorthCust

    NorthCust Active Member

    Home Page:
    Current Bike (Optional):
    2008 Yamaha R125
    License Currently Held:
    UK Full Bike
    *blush* :) hope it helps
  6. Juho Sirviö

    Juho Sirviö New Member

    Location:
    Finland
    Current Bike (Optional):
    Yamaha YZFR 125 2008
    License Currently Held:
    Other
    yyeaaaah..... it didn't work. I'm not sure if I f'd it up or what but it made zero difference. The fluid came out from the reservoir with a good amount of pressure but the brake's still dead.

    Probably going to take the bike to someone who actually knows what their doing and pay a ridiculous price....
  7. AxionUK

    AxionUK Member

    Location:
    Ipswich
    Real Name:
    Maks
    Current Bike (Optional):
    Yamaha YZF R125 (2008)
    License Currently Held:
    UK Provisional (CBT)
    The usual thing producing a hissing noise would be an air leak, but obviously there's no air to be leaking constantly so that idea is already out the window. I'm no expert but I'm pretty sure the hissing sound is normal, as in - I don't know how bad your crash was or what happened but chances are a bunch of dirt/grit got onto the disc/pads, this in turn makes the pads/disc uneven and when you engage the brakes the particles are basically scraping against the brakes. This is what makes the hissing noise and it would explain why it only happens when you're moving. (Solution to this would be to sand down the pads/disc with a really fine grade sandpaper)

    The soft lever however is a different story, I would recommend using a pump (or anything that can blow air into a tight area) to completely empty the brake lines (you might even be able to see if there's any leaks in the "hose") and disassemble the caliper to make sure the pistons aren't seized at all and are free to move with relative ease.
    The other obvious solution is to get a new brake system (excluding the caliper if it works fine) but that's a rather expensive way to go :p
    NorthCust likes this.
  8. Juho Sirviö

    Juho Sirviö New Member

    Location:
    Finland
    Current Bike (Optional):
    Yamaha YZFR 125 2008
    License Currently Held:
    Other
    The hissing sound came after I crashed which wasn't the worst but my bike still took a nice beating. I have a post about it if your interested. Anyways I took the bike to someone who knows what they're doing. Hope the bill wont be too bad
  9. AxionUK

    AxionUK Member

    Location:
    Ipswich
    Real Name:
    Maks
    Current Bike (Optional):
    Yamaha YZF R125 (2008)
    License Currently Held:
    UK Provisional (CBT)
    As a fellow crash-ee I've just had a look at your crash post and the damages and not gonna lie, really quite surprised that it's €700 for the repairs. A lot of my fairings were badly damaged before my crash (I bought it in that state) and I had 1 fairing break in two after the crash. The total repair cost (excluding labour costs) was less than €100 - I bought some fibreglass and fibreglass resin, and used that to bind pieces of plastic together and even form the previously broken off pieces (mostly the places where screws and bolts go). So if you're even somewhat of a handyman and have time on your hands you can save a lot of money too :D

    > Anyways I took the bike to someone who knows what they're doing. Hope the bill wont be too bad
    Hopefully it gets fixed and I'll pray that your bill isn't that much (I'm an atheist but you know what I mean :) )
  10. misiozol

    misiozol Member

    Brake cylinder is cracked or has phisical damage hence hisss sound when applying pressure, its just fluid uder pressure rushing beside it ;)
  11. AxionUK

    AxionUK Member

    Location:
    Ipswich
    Real Name:
    Maks
    Current Bike (Optional):
    Yamaha YZF R125 (2008)
    License Currently Held:
    UK Provisional (CBT)
    > its just fluid uder pressure rushing beside it
    So why is it only happening when moving huh
    Or are you saying there's no pressure when the bike's stationary? :D

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