Hi all. I've got my 74 pretty much dialed in but the front brake is just not bleeding. It is a brand new 14mm MC with steel lines and a brand new caliper with pads. I have quite literally tried everyone's variation of "how to" yet still find my brake not working as it should. It seems perfect, then I roll forward about one revolution and all of a sudden the lever seems to have no pressure. Squeeze it a few times, it works fine for a few pulls and rolls, then it goes limp again. What gives? Any help appreciated.
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Attempt #8 Bleeding Brand New Brake MC and New Caliper/Pads
- Thread starter julienm94
- Start date
jpdevol
Hacker of Frames,Wires and other things
Likely still has some air in the line........air rises; I like to wrap a big rag around the top banjo fitting and crack the bolt quickly (loose, retighten fast) while squeezing the brake lever. Might take a few licks...
Raise the caliper and all lines above the MC then bleed.
jpdevol
Hacker of Frames,Wires and other things
Is there fluid leaking anywhere? (especially in where MC piston is)
Did you bench bleed the MC? Are the caliper and MC OEM Yamaha?
And when you squeeze the MC do you see bubbles?
If not, good chance the passage is clogged. Had it happen on more than one aftermarket MC.
I am a fan of bleeding with a compressor. You run through a little brake fluid but it bleeds in seconds.
If not, good chance the passage is clogged. Had it happen on more than one aftermarket MC.
I am a fan of bleeding with a compressor. You run through a little brake fluid but it bleeds in seconds.
Not a single leak anywhere. I am completely baffled.
Caliper is OEM. I had to get a new MC from Mikes (14mm). Maybe it's that.
I see little bubbles come out from the MC when I slowly press the lever in (avoiding splashing).
This is a very common aggravation and everyone has their favored technique. Sometimes they are just a bitch to bleed. I’ve had some that are perfect in 5 minutes effort and others that I had to walk away from and come back to it the next day. Do a forum search on bleeding the brakes and you’ll see a bunch of techniques. Here was a recent discussion,
https://www.xs650.com/threads/rebuild-front-brake-need-to-bleed-it-nope.58245/
For me, when I get it almost perfect but just not firm enough, I pull the brake lever all the way in and hold it there with a strap and leave it overnight. Usually by morning any remaining micro bubbles have risen to the top, and a few quick squeezes on the lever works them out.
https://www.xs650.com/threads/rebuild-front-brake-need-to-bleed-it-nope.58245/
For me, when I get it almost perfect but just not firm enough, I pull the brake lever all the way in and hold it there with a strap and leave it overnight. Usually by morning any remaining micro bubbles have risen to the top, and a few quick squeezes on the lever works them out.
jpdevol
Hacker of Frames,Wires and other things
Yep, sometimes those "Tiny Bubbles" (que Don Ho music) need their time..
+1 on zip tie the handle down and walk away. Especially when frustration is taking hold.
Seriously epic.
Just my two pence ( or cents) worth but I recently had the same issue on another bike..leaving the bike overnight to let bubbles rise helped but I also took a drill on hammer mode and pressed a backwards fitted bit onto the banjo on the master cylinder..I thought 'what the hell' but it seemed to help agitate the trapped air enough to rise in the lines..obviously I protected the surrounding area incase I slipped with the drill but it definitely helped... I would normally have used the pressurised air method but I couldn't find all the parts in my shed...
I have tried with some success.
