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Discussion Starter #1
Okay, I did a search first and couldn't find anything specific to this. If there is something, sorry for the repeat. (I figure if someone else has already posted up about it, there is no point in killing more trees to print..er, well you know what I mean).

The Problem (besides the nut holding the bars): I bleed the front master, and both calipers. No more bubbles! Brakes feel very good. Come back a week later and the lever travels a little bit further back and there is less feel. Bleed the master (at the bleeder above it) and there will be a couple of bubbles. Back to firm feel....let the bike sit a few days and I have to "repeat" this all over again.
SO...WHERE IS THIS MYSTERY AIR COMING FROM?
I have no leaks anywhere. Not loosing fluid....except what is expelled during bleeding. This has gone on for a year. I have just come to know that I need to d a quick bleed before taking her out.

Anyone experience this? Solutions? Thanks
 

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possibly you're not bleeding it fully. I find it much easier to put a syringe on the bleed nipple and pull a slight vacuum to ensure that the system is sealed and does not draw air back in when bleeding.

I have experienced similar when the caliper pistons were worn and would "settle" off the pads. that was on a 55k mile bike.
 

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could be some air stuck in the lines/calipers/master cylinder... I've heard of guys taking a zip tie around the brake lever/grip and leaving it sit for a day to get the air to flow up into the reservoir
 

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Discussion Starter #4
could be some air stuck in the lines/calipers/master cylinder... I've heard of guys taking a zip tie around the brake lever/grip and leaving it sit for a day to get the air to flow up into the reservoir
I have heard of this too. I have not tried it. I guess I will and let you know.

I've used a vacuum bleeder twice and replaced all fluid with fresh DOT4. May try that AGAIN, since that is always so much fun. LOL
 

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if you do the zip tie on the lever thing it might force fluid out of somewhere too, so it's worth a shot to see what happens
 

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Do you have OEM lines or Stainless Steel? Let's go with that question first. If you have OEM lines, the rubber expands, so instead of the brake fluid going straight down to the calipers, it will make the lines expand, so not all of it is getting to where it supposed to be. Stainless steel brake lines help prevent that.

Then, what is your method of bleeding?

1) Master Cylinder?
2) Rider's Right side of the bike?
3) Rider's Left side of the bike?

Does it still feel like less travel when you pump the brake after a week, i.e. does the pressure build back up, or does it stay the same.
 

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Discussion Starter #7
Do you have OEM lines or Stainless Steel? Let's go with that question first. If you have OEM lines, the rubber expands, so instead of the brake fluid going straight down to the calipers, it will make the lines expand, so not all of it is getting to where it supposed to be. Stainless steel brake lines help prevent that.

Then, what is your method of bleeding?

1) Master Cylinder?
2) Rider's Right side of the bike?
3) Rider's Left side of the bike?

Does it still feel like less travel when you pump the brake after a week, i.e. does the pressure build back up, or does it stay the same.
It is getting air in the master cylinder from SOMEWHERE? I'm not a rocket scientist...but I can rebuild engines. So bleeding a hydrulic system isn't on the "difficult" side of things for me.
Once they are bleed, they have good feel. Yes they have oem rubber hoses, and SS would provide much better feel. BUT, a few days of sitting not being used, and they develope air in the master cyclinder area. I bleed that tiny bit of air, and they are fine... But this has gone on for months. UGH. Where is the air COMING FROM?!

I'm going to ZIP TIE tonight.....Why not.I'm ready to try animal sacrifices at this point.
 

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Hmmm. Maybe there's something wrong with the master cylinder then. Somehow it's allowing air to enter. But then you should have brake fluid spilling also. This is very bizarre. Maybe it's worth it to replace/upgrade your M.C. if you know this is the issue.
 

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Discussion Starter #9
Hmmm. Maybe there's something wrong with the master cylinder then. Somehow it's allowing air to enter. But then you should have brake fluid spilling also. This is very bizarre. Maybe it's worth it to replace/upgrade your M.C. if you know this is the issue.
I strapped a canopy tie around the lever last night. Checked it this morning and it's still at the same pressure, and I didn't notice any fluid YET. We I get home I'm going to look her over again....then, rebuild it. I ordered the factory kit a couple weeks ago. Just am not convinced this is the cure. After Market m/c will be next. I'm sure the misses will appreciate the upgrade. (this is her bike)
 

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if rebuilding it doesn't work you could swap in a different OEM master cylinder if you didn't want to spend the $$ for an aftermarket mc
 
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