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Author Topic: 1981 Master Cylinder onto 1972?  (Read 613 times)

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Offline Mat

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1981 Master Cylinder onto 1972?
« on: June 19, 2010, 05:57:10 PM »
I'm rebuilding a 1972 cb750 from the ground up. The master cylinder has problems and I found one from a 1981 cb750K on eBay, and was wondering if they are interchangeable. Does the 1981 have a large enough reservoir for stock 1972 brakes? Thanks, Mat
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Offline 333

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Re: 1981 Master Cylinder onto 1972?
« Reply #1 on: June 19, 2010, 06:17:29 PM »
More like too large.  Without looking, doesn't the '81 have dual discs?  Or dual pistons?  Maybe both?
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Offline MCRider

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Re: 1981 Master Cylinder onto 1972?
« Reply #2 on: June 19, 2010, 06:19:31 PM »
The reservoir is not the issue. Either has enough. The level goes down over time, you top it off.

The piston ratio is the issue. hard to say till you try it. Is it a 2 brake cylinder going on a 1 brake bike? Might seem a little harsh. If they were both 1 brake bikes, should be OK.
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Offline Alan F.

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Re: 1981 Master Cylinder onto 1972?
« Reply #3 on: June 19, 2010, 07:01:12 PM »
It'll work but it may be a very differently operating system after you install the 81 m/c

Could be more sensitive, could be less.  Be sure you can get a rebuild kit for it before you buy, ebay is a clearinghouse for junk these days and some sellers are less than honest but remail within ebay's rules.

-A
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