Rear MC leaking, need help

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07 Sep 2020 09:05 #834534 by Bama704
Rear MC leaking, need help was created by Bama704
I am about at my wits end with this rear MC. New stainless steel lines, fill up with fluid and try to bleed and it will not move the piston on the rear brake, plus the MC is leaking brake fluid. So, I got a rebuild kit, refilled with fluid and tried to bleed the brakes. Still have brake fluid leaking and can not get any pressure on the brake pedal. I added a new O-ring as well to where the reservoir connects and I will see if it leaks from there too. I just added the o-ring.

I have tarozzi rearsets and am using the plunger with their setup. I think my MC may be from a GPZ 750 but can not be sure, got it when I bought my rear wheel and swingarm.

My questions would be...
1. At this point is my MC shot and should I look to buy a new one?
2. Can anybody identify this rear MC as well?

1977 KZ900
Carbs are late model 1975 28mm
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07 Sep 2020 09:29 - 07 Sep 2020 09:32 #834536 by Skidmark
Replied by Skidmark on topic Rear MC leaking, need help
It looks similar to this one I bought of Amazon, but the brake line attach point is in a different direction. They are not very expensive.

www.amazon.com/gp/product/B07DK8XXL1/ref...01_s00?ie=UTF8&psc=1

I am using this master on my KZ750 with Tarozzi rear sets.

Retired gearhead
'81 KZ-750 E2
'87 Suzuki Savage 650 Street Tracker (lost in the shop fire)
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Last edit: 07 Sep 2020 09:32 by Skidmark.

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  • Scirocco
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07 Sep 2020 12:36 - 07 Sep 2020 12:54 #834550 by Scirocco
Replied by Scirocco on topic Rear MC leaking, need help
Suizide MC !!!! It Looks like someone mix up with two o-rings and flips the seal upside down in the wrong direction. :ohmy: :ohmy: :ohmy:



This is how it has to look right.

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Last edit: 07 Sep 2020 12:54 by Scirocco.

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08 Sep 2020 13:31 #834610 by Bama704
Replied by Bama704 on topic Rear MC leaking, need help
I looked at the orientation for the new rubber and installed on the new piston from the rebuild kit. I noticed I didn't have a retainer so I added one but the issue still persists and it drips brake fluid from the bottom.

Looks like I will be sourcing a replacement MC with the right spacing for mounting and and orientation for my brake line.

1977 KZ900
Carbs are late model 1975 28mm

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10 Sep 2020 07:51 #834726 by Bama704
Replied by Bama704 on topic Rear MC leaking, need help
Got a replacement MC, mine was off of a 91-95 gsxr 750 fyi. Tried bleeding the brakes and still had no rear brake, so I took the rear caliper off and pushed the piston all the way in to try and remove any air from the system, and I went through the bleeding process again. All works now and I finally have a functioning rear brake!

1977 KZ900
Carbs are late model 1975 28mm

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