Bubbly Master Cylinder

[Chiefblueman]

I finally finished installing the Spiegler brake lines on my GenI ABS but can't seem to get a proper firm lever at the front.

I used a Mity-Vac and speed bleeders for the initial fill, then just the speed bleeders pumping the master cylinder. I also used the bleeders conventionally ie: pump, release. I was very meticulous about keeping the reservoir full during the process, but could not get a firm lever. Tied the lever back to the bar overnight, this helped bring the lever up but I still get a higher lever by pumping once or twice. I've tapped on everything, lines, fittings, calipers, ABS unit, MC. Checked all fittings, bone dry. I've had the lever bungied 3 nights, no real improvement after the initial tie back. I have cycled the ABS and bled 3 times.

While gently pumping the brake lever and looking into the reservoir I noticed tiny bubbles coming from the orifice at the bottom. I can see the piston move forward as I squeeze, bubbles come from the reservoir side of the piston. A quick release will sometimes increase the amount of bubbles, a hard squeeze and hold will also produce bubbles. At no time does the lever sink while holding for a good period of time. Sometimes just gently working the lever produces tiny bubbles (Don HO anybody?). Every once in a while a reletively big bubble will emerge. Squeeze and hold will produce bubbles, but after a couple seconds they stop. These tiny bubbles do NOT make me happy NOR do they make me feel fine.

I have worked on, replaced and built from scratch several brake systems. The master cylinder under the floor of my hot rod Ford was a bit of a bitch requiring residual valves becuase the MC is lower than the calipers-wheel cylinders. This one's got me scratching my head a bit.

BTW, I did google search this subject. Any ideas guys?

 

[Aasland]

Bleed the banjo at the master cylinder.

 

[Niehart]

When I changed mine, I also could not get the lines free of air even with the mity-vac. As much as I hate to admit this, I ended up loading the bike on a trailer and taking it to local dealer to have the lines bled.

 

[TheZsdad]

Saw a video awhile back that said the speedbleeders should not be used on initial fill. They are considered a maintenance item.

I wasn't sure by your post if you added the bleeders after an initial bleed or not.

Link posted just in case.

 

[Chiefblueman]

When I changed mine, I also could not get the lines free of air even with the mity-vac. As much as I hate to admit this, I ended up loading the bike on a trailer and taking it to local dealer to have the lines bled.

Never!!!

Bleed the banjo at the master cylinder.

Thanks, I'll do it.

Saw a video awhile back that said the speedbleeders should not be used on initial fill. They are considered a maintenance item.I wasn't sure by your post if you added the bleeders after an initial bleed or not.

Link posted just in case.

Thanks! All good ideas. If I take it to a dealer to bleed the lines I'll never admit it, not even to myself.

 

[TheZsdad]

If the speedbleeders were in on initial bleed it may be worth taking them out and replace with the oem and do a manual bleed.

Dealer may need to do that himself. Take the oem bleeders if you do let the dealer work on it. My two cents anyway. I know,

you only offered a penny for my thoughts. Keep the change.

 

[Chiefblueman]

I didn't even offer a penny for your thoughts but I will offer my thanks for responding to my post.I was only kidding about taking it to the dealer. Not gonna happen. Unlike Mr. Niehart, I've still got a little pride.

I've got a few more tricks up my sleeve.

I did install the speed bleeders along with the brake lines. It was pretty easy to get the system full using the Mity Vac. The Mity Vac sucked the fluid right through the Speed Bleeders. I never use the Mity Vac as the only brake bleeding method. Once I got good flow through the bleeders I removed the vac and used the Speed Bleeders as they were intended and was able to get bubble free fluid to exit the bleeders. I've got enough lever to easily ride the bike, just can't get that last bit of trapped air out. At this point removing the bleeders would possibly introduce air to the caliper.

Part of this process was removing the pistons and seals from the calipers cleaning, inspecting and reassembling with new pads. BTW, did you guys know GenI calipers are the same ones used on GenI and II FZ1's? Since I own a GenI FZ1 and have a spare set of calipers for it off a GenII, I have plenty of spare parts if needed.

Anyway, I'm thinking those empty calipers could have trapped some air. Maybe I'll open the bleeders and push the pads back in. Definitely going to bleed the banjo,

why didn't I think of that?

 

[Chiefblueman]

Update on the big brake bleed. I bled the banjo as suggested by Aasland, a little improvement. Pushed the pistons back into the calipers with the speed bleeders barely cracked, minute improvement. Cycled the ABS, bleed some more. Bungie brake lever overnight, cycle the lever, over 3 days and nights , rinse and repeat. Finally!!!! No more tiny bubbles and firm lever. Only took a week or so.

Thanks for the help, guys!

What did I learn from this experience?

1. If you want braided stainless brake lines on your FJR, buy one that already has them on it.

2. If yer ol' dad Niehart sez itsa pain in the ass and not worth doin' , don't ask questions, just don't do it.

 

[escapefjrtist]

Good for you 'blueman, keep after it until it's fixed!

Had a similar issue with my Tenere clutch last weekend...PITA to get the air out.

--G

 

[dcarver]

This thread made up my mind.

I'm taking KrZy8 up north to have Pops install the SS lines.

While there I can eat his food, drink his booze, borrow his trailer, have his tech do the job!

I mean, really, does it get ANY better than this?

 

[Chiefblueman]

You sound like a smart man, dcarver, although I have heard others in this community express very different sentiments.