Rebuilt Master Cylinder Seca 550..How do I bleed??

Hi,

Just took off my master cylinder today and put in a rebuild kit. Put the system back together and now I can't seem to bleed the system. Any tips and/or suggestions will be more than welcome. I've spent the better part of today in frustration with this.

Symptom: I filled the master cylinder with brake fluid but I can't seem to generate any pressure in the system. Also nothing comes out of the hole when I remove the brake line and squeeze the lever either.

Thanks in advance.

 

A vacuum bleeder is the best way. It fits on the bleeder screw and draws the fluid though. Once it fills the system, bleeding can be finished in the conventional method.

 

If you are doing it by hand, it WILL take a long time. Can it be done? Yes. I do it that way cuz I've been too cheap to buy a vacuum tool. I do it in stages.

1. First, I bleed the MC. I keep a finger over the outlet to allow air to squeeze past but not suck back in. Eventually I can get pressure.
2. hook the first line section to the mc, pinch fingers at the holes on the other end, bleed through. Hook up the next section, etc...
3. hook up to the caliper and do the same...........
4. finish working air out of the system.

MAKE SURE THAT YOU ARE FEATHERING the brake lever, not using full strokes. You may get a larger bubble of air, but mostly I get little tiny trickles of air coming up, and ther can be long periods of nothing. It just takes time.

Keep at it, you'll eventually get it.

Actually I'm gonna be doing a third MC job this spring. Two for other people, this one for myself.

Dave

 

http://www.harborfreight.com/catalogsea ... ke+bleeder

gotta love Harbor Freight ...

 

IF ...

The Master Cylinder is performing precisely as it should, with the Seals PUMPING Fluid out of the MC, ... a simple "One Man Bleeder" will do the trick.

Add Fresh Fluid to the MC
Open the Bleeder furthest from the MC
Pump Brake Fluid OUT of the System, ... until the Fluid exiting the Bleeder Tube is as clean as the Fresh Fluid you added.

Once the Lines are purged of Old Fluid.
Close the Bleeder.
Pump the Brake Lever until Hydraulic Pressure is achieved.
Open the Bleeder.
Pull the Brake Lever to the Grip and HOLD.
Close the Bleeder.
Repeat as necessary until all Air Bubbles are forced out of the Caliper.

 

If it doesn't pump fluid at all, maybe you put the seals in backwards, OR the tiny hole in the bottom of the M/C reservoir is plugged. It's in one of the "false drillways" in the bottom.

 

Tiny hole is open, seals are in correctly. Used a vacuum tool to bleed the system. Brakes are now working but remain spongy. Do I need to change the lines? Can I get stainless steel lines for this bike? If so, where? 1982 Seca 550.

Thanks in advance.

 

If the lines are original you should change them, yes.

I got my stainless lines for my 550 Secas from XJ4Ever; including the custom-length uppers for the shorter bars. Highly recommended upgrade.

 

Ordered the stainless steel lines today. Will report back on the outcome. I wasn't diggin' the mushy feel even after they were bled properly.

 

Stainless lines are on, master cylinder rebuilt, system bled. Now I have a very strong set of front brakes. Thanks all for the advise.

 

If you didn't rebuild the caliper you're not finished, trust me.

Left alone, the caliper will start to generate the "I can't roll the bike backwards" syndrome; when it does you'll need to rebuild it as well.

I hope you at least replaced the 30-year old pads. And of course you've already checked the rear shoes for delamination, right?