Topic: Bleeding rebuilt brakes CB 550

[mthomas2911]

I'm trying to get the rebuilt brakes on my 1974 CB 550 going again.  I replaced the lines with Slingshot stainless steel lines.  I had a dealer rebuild the master cylinder with OEM parts.  Took out the piston and cleaned up the caliper.  I also installed a speed bleeder.

So everything is back together and it is time to fill the system with brake fluid.  I attached a hose to the speed bleeder and loosened it, filled the reservoir with fluid, and began pumping the brake lever.  Nothing happens.  The fluid does not pump out of the reservoir.  Pump pump pump - nothing.  I took the speed bleeder out and pumped on the brake lever - nothing.  I can hear a wooshing sound coming from the caliper each time I pump the lever with the bleeder out but no fluid moves out of the reservoir.

The rebuilt master cylinder sat on my work bench for several months before I got the time to put everything back together.  I had it in a sealed plastic bag but am wondering if something may have "dried out" and this is what's causing the inability of it to pump fluid.

If any one can shed some light on what I may be doing wrong I sure would appreciate.  Thanks.

Mark T.

[calj737]

You inadvertently posted this topic in the 750 Auto section... Perhaps a modrator will pop by and move it for you-

Meanwhile, the new SS line from Slingshot, does that connect directly to the stock hard line, and are you still using the stock 3-way pressure switch?

First thing I do, is begin disconnecting the line after the MC and confirm fluid is leaving the MC. But be careful, brake fluid is exceptionally good at removing paint! Keep moving toward the caliper with confirmation of the flow. It can take a while to move the fluid through the entire line, but your method of opening the bleed screw helps.

If you've confirmed flow, fill the reservoir, tie the handle back, and let it sit a while. That may help circulate the fluid.

Also: can you confirm the piston was installed with a new seal correctly? Does the piston move at all yet? (It may not if there's no hydraulic pressure)

[HondaMan]

My "lazy man's brake bleed" is:
Plug a length of [clear is best] tubing onto the speed bleeder head and wire the other end up to the master cylinder so it sits a little higher than the master reservoir. This will prevent it from bubbling out. Bend the open end AWAY from anything with paint on it...then crack open the bleeder about 1/4 turn and fill up the reservoir, and with a piece of wire, pull in the end of the brake lever about 1" and tie it there. Leave the lid of the reservoir loose so it can breathe. Come back in the morning, and it usually has bled itself while you sleep. Tighten the bleeder up, refill the reservoir, and check for any tiny bubbles that might be left by operating the handle gently a few times while looking in the reservoir (with safety glasses, and away from the painted gas tank!).

Works every time...

[BobbyR]

+1 on Hondaman's suggestion. I have and odd thing I have done. Fill the MC 1/2 normal and tap the brake handle so gently nothing squirts out.  As you tap you will see bubbles com out. When i say tap I mean tap or you will make a mess.