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Joined: Jan 2013
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G
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Circlip is out, but rest won't move. Any tricks to pull/press out ? Or replacement sources ?

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Air pressure might push it out.


1968 BSA Firebird
1200 Sportster
XS 1100
1972 Rickman 125
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First, what's a Lyster?

But also, here's a trick for you. It can get messy but really applies a lot of pressure. It works awesome on stuck caliper pistons.

Make a fitting that allows you to hook a hand pump grease gun to the outlet port on your master cylinder.

Then.....you pump the grease gun...... and then, thousands of pounds of pressure are applied to that stuck piston.

The only problem with this strategy on a master cylinder is that a master cylinder, unlike a caliper, will have drillings in the bore for fluid to pass through. You will have to find a way to seal up those fluid transfer holes.

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Oil or grease is far safer than air, air once at the pressure required to move a stuck piston contains too much energy and the piston will fly across the room.

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Or, first knock the piston in to break it free of the bore then use another master cylinder connected to it using water or very light oil such as Marvel Mystery Oil to push the piston out.
Unless you plan to sleeve that master it probably is not worth messing with.

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As I recall, the Lysters used Hurst-Airhart brake calipers and master cylinders. Dunno if parts are still available, but they were pretty popular for go-karts. Stuart, google Lyster. Colin Lyster built racing and cafe frames in the late '60s/early '70s.

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only seen a grainy picture of a lyster master cylinder .
the internet says
that the master cylinder used on the first
honda 750s in 1969 were an unlicensed version
based off of ideas of Lysters
master cylinder design work ( of a bar mounted lever , cylinder and Reservoir )

honda exploded. view .

[Linked Image from images.cmsnl.com]

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Googled Lyster "images." This link shows Lyster discs and master cylinder on Norton cafe: http://progress-is-fine.blogspot.com/2012/11/lyster-frame.html They look like what I recall from my days working for Lyster's US importer. The resevoir cap is a plain alloy disc held on with screws, not like the Honda's screw-on. The short 7/8" tube extending from the subframe back towards the shocks is where the rear master was clamped.

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I found a shop to press apart the piston. The system looks identical to the Lyster- Kennedy racer photo, has the single yellow line off the master, splits to two lines to brake assembly. Does anyone know where to get a rebuild kit - spring, o rings, etc for master ? Still to be determined is condition of the lower components.

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Not sure how to post some photos of the master. The deposits inside the cylinder where the outer O ring stuck have been honed off. Replaced outer O ring with nearest eyeball and touch matching O ring.

Do old O rings swell ? Should the O rings have much larger diameter than the piston ? If so, how much ? It seems too difficult to insert piston now,

Eyeballing from outside, the spring looks like it will have very little compression ( perhaps 1/8 - 3/16 " ) after inserted and circlip in place. I don't know If that will be enough to return the piston fully out with current tension of two inner O rings.

Any advice appreciated.


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