Round metal disc with screws inside the master brake cylinder

[80xs11socali]

Fellow yammies, I tore down both master brake cylinders today. I am missing the metal round pieces in BOTH OF THEM. No wonder the pistons wouldn't pop back out.

I'm reaching out to all of you to sell me your extra pieces with the screws or send me to a source where I can buy them. I need 2 discs and 4 screws.

[cajun31]

Fellow yammies, I tore down both master brake cylinders today. I am missing the metal round pieces in BOTH OF THEM. No wonder the pistons wouldn't pop back out.

I'm reaching out to all of you to sell me your extra pieces with the screws or send me to a source where I can buy them. I need 2 discs and 4 screws.

If you can you need to show pictures of what you say you are missing. I am not aware of a metal disc with screws in the master cylinder. Here is a schematic of the front master ... identify which piece you are missing. Yamaha Motorcycle 1980 OEM Parts Diagram for FRONT MASTER CYLINDER | Partzilla.com

[80xs11socali]

I know my post is confusing. Here's a screen grab from youtube video. I think this holds the plastic reservoir to the master cylinder.

Thank you.

[cajun31]

I know my post is confusing. Here's a screen grab from youtube video. I think this holds the plastic reservoir to the master cylinder.

Thank you.

Where did you get the video. None of my master cylinders have ever had that disc in them. On the xs11's there is a large o ring that seals the plastic reservoir to the base. The screws that secure the lid and other components are generally long enough to extend through the reservoir all the way to the metal base on the fronts and there a four screws that extend up through on the rears with bolts on top. If you do have a master like you see in the video then it is something that was bought and put on. Maybe someone more knowledgeable then me can chime in if I am not correct. If you have original XS11 masters then the appropriate rebuild kit for your year and model of bike should suffice to get you going. That is unless you have severe pitting etc... going on. Have you checked to be sure the spooge holes are open and working properly. If not search the maintenance section on brakes and there is a thread on them and how to clean.

[bikerphil]

The older style 78-79 front masters have that disk.
The screws that hold the top cover on are short and do not pass thru the fluid reservoir on the 78-79. The disk and it's 2 screws hold the reservoir tight to the metal body.

[cajun31]

The older style 78-79 front masters have that disk.
The screws that hold the top cover on are short and do not pass thru the fluid reservoir on the 78-79. The disk and it's 2 screws hold the reservoir tight to the metal body.

Interesting. When I researched all the schematics on Partzilla for the 78-79 standards there was no indication of that disc being present. At least it isn't shown as a replaceable part. Thanks for the update.

[Radioguylogs]

Seems like a better design than the later years.

Mine are prone to leaking around the bottom of the reservoir, so I have to pull them apart, replace the O-ring, and repaint them every 10 years.

[80xs11socali]

I'm so confused. LoL

I'll post pictures tomorrow.

[80xs11socali]

Where did you get the video. None of my master cylinders have ever had that disc in them. On the xs11's there is a large o ring that seals the plastic reservoir to the base. The screws that secure the lid and other components are generally long enough to extend through the reservoir all the way to the metal base on the fronts and there a four screws that extend up through on the rears with bolts on top. If you do have a master like you see in the video then it is something that was bought and put on. Maybe someone more knowledgeable then me can chime in if I am not correct. If you have original XS11 masters then the appropriate rebuild kit for your year and model of bike should suffice to get you going. That is unless you have severe pitting etc... going on. Have you checked to be sure the spooge holes are open and working properly. If not search the maintenance section on brakes and there is a thread on them and how to clean.

Cajun, where do you source the o ring that goes between the plastic reservoir to the base?

[cajun31]

Cajun, where do you source the o ring that goes between the plastic reservoir to the base?

That O ring generally is not bad to the point of actually falling to pieces. I have never had to replace it and honestly I think you would have to probably find something close. If you reservoir is not leaking around the base then it is probably ok. The problem with them leaking starts when you pry to reservoir off of the base. You will need to do that by the way to gain access to the spooge hole that I mentioned in my previous post. It sounds like you have the later master because you do not have the metal disc in yours. Your cap screws are probably long enough to actually screw down into the base. What I do is use a thin layer of yamabond on the base after I clean the spooge hole if I experience brake fluid seepage after reassembly. No guarantees that I might not have to clean that spooge hole again in the future so I may have to disassemble again in the future. On the later masters once you have them apart to the point of having to separate the plastic reservoir from the base you can actually turn it slightly by hand while on the base to give you better access to remove it from the base. That is why I said put a light coat of yamabond when sealing it so that it doesn't make the future job of removing it again if necessary. I do believe the root of your problem right now is that those spooge holes are clogged. The symptom of your brakes not releasing is what indicates that and is what the spooge hole does.