Can't get all the air out of Right Front Caliper brake line

[WingMan71]

So, I'm bleeding the integrated foot brake pedal system on my '87 GL1200A.

So far I've put 5 full master cylinders full of fresh fluid through the line to the right front caliper and I still have air bubbles coming out of it ! ! !

What the heck, just how long is that line that it can take this much fluid and still not be flushed out?

Any advice would be welcome.

Thanks!

[SIR tricky]

Why did you need to bleed the brakes?
Did you have the caliper off?
Is it just to change the fluid?

Give us some history, we can't guess what you did?

If your getting air out, it must be getting in, give us a clue

[WingMan71]

It was time to do it. Two years on the existing fluid, plus the foot pedal was starting to feel a bit spongy. So, just changing fluid. No parts removed.

After five MCs full of new fluid I have nice clean fluid coming out of the caliper bleed, but still with air bubbles in it.

No, I did not let the fluid level in the MC get too low and suck air into the line.

I think maybe I'll bleed the rear caliper now and see if that makes any difference going back to the front later. The FSM says to bleed the right front caliper first and then the rear caliper, so I'm following procedure.

***

[K Bergen]

Are you using a vacuum bleeder?
If so the air is likely entering through the bleed screw threads in which case you're done and good to go.

[WingMan71]

Are you using a vacuum bleeder?
If so the air is likely entering through the bleed screw threads in which case you're done and good to go.

Not using a vacuum bleeder, but I'm beginning to think that the air is coming through the bleed screw threads like you say.

Giving up for the night. Will pick up on it again tomorrow and see how it goes.

***

[pstelter]

I vote that these are air bubbles from the bleed screw threads. When did the fluid change-out this season, the 0.25 inch tubing that I had was a little too large for the bleed screw and would come off easy. You can try to put some lubricant on the bleed screw threads to seal off the air coming through. Good luck.

- P

[WingMan71]

Well, the job is done, the brakes all buttoned back up, and all is well. The pedal is firm now and the mushiness gone.

Air must have been coming in around the bleed screw threads as suggested by some.

I think I'll get a set of speed bleeders for the bike and replace the original bleed screws with them. Perhaps they'll fit a bit tighter, plus make the job easier as well.

Thanks for the help!