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Thread: GS1000G Rear Master Cylinder replacement

  1. #1
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    Default GS1000G Rear Master Cylinder replacement

    My 81 GS1000G I just pulled out of storage has a roached rear master cylinder. So far, soaks in carb dip, compressed air, nothing will budge the old piston so I can rebuild it. Somebody suggested you could install a grease fitting and use grease to push it out.

    What I am wondering is if there are other, maybe newer bikes where the odds of finding a replacement in good shape are better. I know Suzuki used a very similar design for a long time.

    Edit: Before you ask, yes the circlip has been removed,
    Last edited by nate665; 04-12-2021 at 01:16 PM.

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    It probably interchanges with lots of Suzukis of various vintage. Find a part number on a parts vendor's site, then find on the same site a tool for looking up part numbers. It'll give you a list of bikes the same part is used on. I doubt you'll find a part number for a complete master, but a search on the master body might be good enough. Maybe cross reference with some other parts that might be different on other bikes. I can tell you right away that the '79-81 GS 850 interchanges, probably the 850 and 1000GL too.

    A used part from a salvage yard selling on eBay should be serviceable.
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    It's extremely common to find the bore pitted after 40 years (with infrequent fluid changes.)

    Salty_Monk posted some info about adapting a newer master on his 1000. You may want to search out the info since he's done the R&D for you already.

    Found the thread...https://www.thegsresources.com/_foru...ng-more-modern
    Last edited by Nessism; 04-12-2021 at 06:29 PM.

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    Perfect, exactly what I was looking for.

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    Just a quick "for future reference".

    The trick to getting a stuck rear master apart (frozen piston) is a 1/8 grease nipple. It threads right on and then use the grease to push the piston out.

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    I think the DL650 one would be a decent fit as well, you may not need the sleeve nut as the shaft is longer, other than that it appears to be the same master as the EX300 one...

    The 300 one is more plentiful and cheaper on that auction site for much newer parts though (or at least it was).

    Mine is still working fine after quite a few miles
    Last edited by salty_monk; 04-16-2021 at 12:34 AM.

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    After finding the grease nipple trick to get it apart and seeing the bore of my stock one is actually pretty good, decided to just rebuild it.

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    Just say'in, A few yrs. back, I got a rebuild kit for my front GS1100E master, from "ALL BALLS Racing" about 1/2 of the parts fit & 1/2 didn't fit. I was in a hurry, didn't give them a chance to straighten it out, just used their parts & reused some of my parts & got it going.
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    Quote Originally Posted by rphillips View Post
    Just say'in, A few yrs. back, I got a rebuild kit for my front GS1100E master, from "ALL BALLS Racing" about 1/2 of the parts fit & 1/2 didn't fit. I was in a hurry, didn't give them a chance to straighten it out, just used their parts & reused some of my parts & got it going.
    My internals are trashed, so here's hoping my rebuild kit (I think it's a K&L) fits.

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