Author Topic: EZ Way to Bleed a CB750 Master Cylinder  (Read 10330 times)

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Offline BobbyR

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EZ Way to Bleed a CB750 Master Cylinder
« on: August 04, 2007, 11:47:24 am »
Brakes went mushy on me and there was brake fluid down by the handle so genius that I am I realized the cylinder must be leaking. I called a really good Honda dealer and ordered all of the parts down to the plastic washer under the diaphragm. I only wanna do this job once.
I will not describe removing the circlip. I finally it out by wit, guile, and brute force. I flushed all the gunk in there out with denatured alcohol  and replaced all the parts.

Of course I had no handle so I tied it down overnite which is a trick I read about - but no dice. I opened the cap and just tapped the handle a fraction of an inch to see if fluid was going into the cylinder and a bubble popped out of the two holes. Now I kept tapping, NOT  enough to have it squirt out just enough to ripple the surface. I kept tapping and more bubbles came out, finally they stopped and when I put the cap back on, I had a rock hard handle. With the stainless line and the rebuild, the front brake is really good at stopping the bike. Remember just gentle squeezes.  Worked for me and maybe it will work for you.
Dedicated to Sgt. Howard Bruckner 1950 - 1969. KIA LONG KHANH.

But we were boys, and boys will be boys, and so they will. To us, everything was dangerous, but what of that? Had we not been made to live forever?

Offline UnCrash

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Re: EZ Way to Bleed a CB750 Master Cylinder
« Reply #1 on: August 04, 2007, 12:49:30 pm »
This technique didn't work for me.

It got me most of the way there, but it wasn't until a fellow member told me to leave the brake lever engaged all night that I had firm brakes.

Just my 2 scentz
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Offline dpen

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Re: EZ Way to Bleed a CB750 Master Cylinder
« Reply #2 on: August 04, 2007, 01:19:32 pm »
This method has been used for years on everything from truck clutches to brake m/cyls

You don't have to actually tap the lever

just squeeze it gently until the air bubbles pop up & release it

This may have to be done a dozen or more times to get all the air out but, as you've experienced, it works a treat

Offline BobbyR

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Re: EZ Way to Bleed a CB750 Master Cylinder
« Reply #3 on: August 04, 2007, 02:19:43 pm »
Well I reinvented the wheel. Yes you are right it is more like a gentle very short squeeze.
Dedicated to Sgt. Howard Bruckner 1950 - 1969. KIA LONG KHANH.

But we were boys, and boys will be boys, and so they will. To us, everything was dangerous, but what of that? Had we not been made to live forever?

Offline tortelvis

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Re: EZ Way to Bleed a CB750 Master Cylinder
« Reply #4 on: December 14, 2007, 09:05:14 am »
Done this many times; fill with brake fluid, leave resevoir lid off and just crack the lever until you see bubbles. Tie it off, leave overnight, job done!

Offline Jay B

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Re: EZ Way to Bleed a CB750 Master Cylinder
« Reply #5 on: December 18, 2007, 04:12:55 pm »
Yep, the MC circlip must be "cursed" out of there. No better way to describe it I can think of. Also, when you are working on a MC, if you have good clean fluid in the system, try this. Put everything back together, wiggle the lever like you said to get air out, then remove the caliper and gently squeeze the piston back into the bore. Gets the air out of the lines easily. This is basically back bleeding the brakes just using the fluid in the caliper. Note: if you have removed and drained the brake line there may not be enough fluid in the caliper for this to work.
Jay
'77 CB550K
'74 CB350F cafe
2001 Road King
'73 CB175

Offline Terry in Australia

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Re: EZ Way to Bleed a CB750 Master Cylinder
« Reply #6 on: December 18, 2007, 04:29:02 pm »
Pish Posh, the only way to get air bubbles out, is with "Terry's Patented Suck it and See" method.

All you need is ten feet of aquarium hose, and a bottle of Makers Mark, or Jack Daniels, or if you're low on funds, Jim Beam.

Attach the hose to the bleed nipple on your caliper/s, (make sure the reservoir is full first) just "crack" the nipple" and with one continuous inhalation, suck on the end of the hose like Linda Lovelace! Just before you realise that you need to exhale, tighten the nipple, take a breath, and repeat.

Every now and then it might be necessary (particularly if you're fitting braided lines to a twin disc set up) to blow any brake fluid out of the lines, just remember which end of the hose goes in your mouth, and which one was attached to the nipple. If you put the wrong end of the hose in your mouth, take a swig from the Makers Mark, and continue. No need for thanks, just send me some Bourbon. ;D



« Last Edit: December 18, 2007, 05:56:12 pm by Terry in Australia »
I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

Offline Jay B

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Re: EZ Way to Bleed a CB750 Master Cylinder
« Reply #7 on: December 18, 2007, 05:50:30 pm »
I dunno Terry, I usually use a good grade of tequila like Patron to rinse brake fluid from the palate. Makers Mark tends to be reserved for fuel system work in my shop.
Jay
'77 CB550K
'74 CB350F cafe
2001 Road King
'73 CB175

Offline Terry in Australia

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Re: EZ Way to Bleed a CB750 Master Cylinder
« Reply #8 on: December 18, 2007, 05:59:25 pm »
Fair enough mate, just as long as you're not using Chivas Regal for anything but oil changes, I can forgive your departure from accepted procedure, ha ha! ;D
I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"