[unkleremis]

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My master cylinder is leaking brake fluid. I know of a GL1200 master cylinder for sale cheap. My gut tells me that it should work but I thought I should check it with y'all before I get it.

Thanks in advance!

Mike

 

[Silicon Sam]

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I am not sure about the brake light switch arrangement on the GL1200 master, but not knowing the year of your bike, I'd say there is a very, very good chance it'll work on a 1983 GL1100. The '83 and the GL1200 have the exact same front brake caliper setup. The front master only pumps 1 caliper.

The master cylinder of the '80-'82 pumps 2 calipers, so that would not be a good match at all.

 

[Silicon Sam]

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Where's it leaking from, BTW?

 

[unkleremis]

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Woops, guess I should have mentioned that my bike is a 1980 and the master cylinder I am looking at is from a 1986 1200.

And it appears to be leaking from the lid. At first I thought it was just not tightened down enough but I really cranked it down and while that helped, it is still leaking.

Mike

 

[Silicon Sam]

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Sounds like a simple o-ring replacement under the reservoir cup then. Odd size according to the Honda pages, 39.7 or 40mm diameter by 3.5mm thick. The '82-'83 uses a 27mm x 2.5 o-ring.

Why not just buy a replacement fluid cup that comes with a new o-ring?

First check the available hardware stores for a 40mm x 3.5mm o-ring. 3mm is lots more common than 3.5mm

----------------------

Just checked, my Harbor Freight o-ring collection does indeed have a 39.7mm x 3.5 o-ring in it. I can send you one for the postage.

 

[Silicon Sam]

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Leaking from under the lid, or under the cup? Either way, a replacement cup comes with a new lid as well.

 

[unkleremis]

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If you could send me the o-ring, that would be great. Do you have a paypal account and how much do you want for the postage?

and it appears to be leaking from under the lid.

Mike

 

[Silicon Sam]

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Well, if it's leaking between the lid and cup, the o-ring won't help much. The o-ring goes under the reservoir cup. Is the cup only half full or less?

 

[unkleremis]

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Bummer.

Yeah, it tends to sit at about half full, or just under.

 

[Silicon Sam]

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Does your lid have that big chunk of rubber in the top? Have you removed it and inspected it for holes?

 

[unkleremis]

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YEah, it has the rubber thing. I didn't see any obvious holes, but I'll take a closer look at it.