Page 1 of 3 123 LastLast
Results 1 to 10 of 22

Thread: Machine Shop Question

  1. #1
    Join Date
    Sep 2018
    Location
    Edmonds, WA
    Posts
    403

    Default Machine Shop Question

    Hello again. I'm working on rebuilding the top end of my 1979 GS850.

    For those of you with vintage engine rebuild experience, do you always send your head and block to a machine shop be resurfaced, cylinders honed, etc? Is it best practice? I recognize how important it is to make sure the surfaces are flat, and it's an old engine, I've no idea when it was last opened up. Lol, maybe it's a no brainer. Thought I should ask what you guys prefer to do though. I decided to rebuild the top end because it had a chronic oil leak and I thought some some fresh gaskets, piston rings, etc., wouldn't hurt
    Last edited by RustyTank; 01-25-2021 at 08:29 AM.
    1979 GS850G, currently being rebuilt from the frame up. We shall see how that go's
    "The two most powerful warriors are patience and time" - Leo Tolstoy
    "Be yourself, everyone else is already taken" - Oscar Wilde
    "Do things for people not because of who they are or what they do in return, but because of who you are" - Harold S. Kushner

  2. #2
    Join Date
    Oct 2020
    Location
    North Lincolnshire - UK .
    Posts
    143

    Default

    No need to skim head or block unless they are warped or have surface damage.
    Cylinders only need honing if fitting new rings.
    A simple strip and maintenance rebuild of a good engine should only need a good clean up and fresh gaskets ,stem seals etc.
    Mikuni Viton Choke Plunger Seat Renewal.
    VITON Choke plunger seals .KAWASAKI Z1,Z900,Z650,Z1000,Z1R,SUZUKI GS1000,GSXR,RF | eBay

    Air Corrector Jets for Mikuni VM 24, 26 and 28mm carbs .

    https://www.ebay.co.uk/itm/254380193...84.m1555.l2649




  3. #3
    Join Date
    Sep 2018
    Location
    Edmonds, WA
    Posts
    403

    Default

    Quote Originally Posted by zed1015 View Post
    No need to skim head or block unless they are warped or have surface damage.
    Cylinders only need honing if fitting new rings.
    A simple strip and maintenance rebuild of a good engine should only need a good clean up and fresh gaskets ,stem seals etc.
    Well, I was planning on installing new piston rings.
    1979 GS850G, currently being rebuilt from the frame up. We shall see how that go's
    "The two most powerful warriors are patience and time" - Leo Tolstoy
    "Be yourself, everyone else is already taken" - Oscar Wilde
    "Do things for people not because of who they are or what they do in return, but because of who you are" - Harold S. Kushner

  4. #4
    bwringer's Avatar
    bwringer is offline Forum LongTimer Bard Award Winner
    GSResource Superstar
    Super Site Supporter
    Join Date
    Oct 2003
    Location
    Indianapolis
    Posts
    16,777

    Default

    If the bore measures consistently (measuring ring end gap at several points) I use a flex-hone to create a nice crosshatch for seating new piston rings. It sort of looks like a giant bottle brush with abrasive balls on each strand.

    One source:
    https://goodson.com/collections/flex-hones (the 2-3/4" size should be correct for standard 69mm GS850 bores. I'm about 90% sure that mine is 240 grit).

    A few seconds per cylinder using a cordless drill works quite nicely. Keep it moving up and down, use slow speed and lots of motor oil (yep, it's messy as hell) and don't stop or start while in the bore. I support the block with wood over a large pan and do the honing out in a corner of the yard, wearing old pants and boots because oil goes everywhere.
    1983 GS850G, Cosmos Blue.
    2005 KLR685, Aztec Pink - Turd II.3, the ReReReTurdening
    2015 Yamaha FJ-09, Magma Red Power Corrupts...
    Eat more venison.

    Please provide details. The GSR Hive Mind is nearly omniscient, but not yet clairvoyant.

    Celeriter equita, converteque saepe.

  5. #5
    Join Date
    Sep 2018
    Location
    Edmonds, WA
    Posts
    403

    Default

    Quote Originally Posted by bwringer;[URL="[URL
    tel:2638673[/URL]"]2638673[/URL]]If the bore measures consistently (measuring ring end gap at several points) I use a flex-hone to create a nice crosshatch for seating new piston rings. It sort of looks like a giant bottle brush with abrasive balls on each strand.

    One source:
    https://goodson.com/collections/flex-hones (the 2-3/4" size should be correct for standard 69mm GS850 bores. I'm about 90% sure that mine is 240 grit).

    A few seconds per cylinder using a cordless drill works quite nicely. Keep it moving up and down, use slow speed and lots of motor oil (yep, it's messy as hell) and don't stop or start while in the bore. I support the block with wood over a large pan and do the honing out in a corner of the yard, wearing old pants and boots because oil goes everywhere.
    Great info bwringer, thank you. I just watched a vid of a guy doing something similar to hone the barrels of his GS550. Not the exact same tool but similar idea.
    1979 GS850G, currently being rebuilt from the frame up. We shall see how that go's
    "The two most powerful warriors are patience and time" - Leo Tolstoy
    "Be yourself, everyone else is already taken" - Oscar Wilde
    "Do things for people not because of who they are or what they do in return, but because of who you are" - Harold S. Kushner

  6. #6
    Join Date
    Sep 2018
    Location
    Edmonds, WA
    Posts
    403

    Default

    What do you guys use to make sure the head and block are flat? Just a simple level?
    1979 GS850G, currently being rebuilt from the frame up. We shall see how that go's
    "The two most powerful warriors are patience and time" - Leo Tolstoy
    "Be yourself, everyone else is already taken" - Oscar Wilde
    "Do things for people not because of who they are or what they do in return, but because of who you are" - Harold S. Kushner

  7. #7
    Nessism's Avatar
    Nessism is offline Forum LongTimer GSResource Superstar
    Past Site Supporter
    Super Site Supporter
    Join Date
    Mar 2006
    Location
    Torrance, CA
    Posts
    33,704

    Default

    Quote Originally Posted by RustyTank View Post
    What do you guys use to make sure the head and block are flat? Just a simple level?
    If you open the factory manual for your bike you will find clear instructions on how to check the block and head for flatness. Failing that, you can google "how to check cylinder head for flatness." The procedure in the search is basically same as the FSM procedure.

  8. #8
    Join Date
    Oct 2020
    Location
    North Lincolnshire - UK .
    Posts
    143

    Default

    Quote Originally Posted by RustyTank View Post
    What do you guys use to make sure the head and block are flat? Just a simple level?
    Use an engineers straight edge or steel rule on its side and try slipping a feeler gauge between it and the clean gasket face in various directions, diagonally etc ( tolerances are in the factory manual ) but chances are the head will be fine.
    Last edited by zed1015; 01-25-2021 at 12:13 PM.
    Mikuni Viton Choke Plunger Seat Renewal.
    VITON Choke plunger seals .KAWASAKI Z1,Z900,Z650,Z1000,Z1R,SUZUKI GS1000,GSXR,RF | eBay

    Air Corrector Jets for Mikuni VM 24, 26 and 28mm carbs .

    https://www.ebay.co.uk/itm/254380193...84.m1555.l2649




  9. #9
    Join Date
    Sep 2018
    Location
    Edmonds, WA
    Posts
    403

    Default

    Quote Originally Posted by zed1015 View Post
    Use an engineers straight edge or steel rule on its side and try slipping a feeler gauge between it and the clean gasket face in various directions, diagonally etc ( tolerances are in the factory manual ) but chances are the head will fine.
    Yeah, that's where I was coming from. Wanted to know how to check for gaps, etc. Thanks man. That actually helps a lot.

    Quote Originally Posted by Nessism View Post
    If you open the factory manual for your bike you will find clear instructions on how to check the block and head for flatness. Failing that, you can google "how to check cylinder head for flatness." The procedure in the search is basically same as the FSM procedure.
    Well don't I feel silly. I didn't even think to look in there. Thanks for the heads up Nessism.
    Last edited by RustyTank; 01-25-2021 at 11:44 AM.
    1979 GS850G, currently being rebuilt from the frame up. We shall see how that go's
    "The two most powerful warriors are patience and time" - Leo Tolstoy
    "Be yourself, everyone else is already taken" - Oscar Wilde
    "Do things for people not because of who they are or what they do in return, but because of who you are" - Harold S. Kushner

  10. #10
    bwringer's Avatar
    bwringer is offline Forum LongTimer Bard Award Winner
    GSResource Superstar
    Super Site Supporter
    Join Date
    Oct 2003
    Location
    Indianapolis
    Posts
    16,777

    Default

    One thing to bear in mind is that this is an air-cooled engine; the head gasket only needs to seal to the block in a ring around each cylinder, the center cam chain tunnel, and at the oil passages at each corner. The head gasket has "fire rings" around each cylinder, and usually a sealing ring around the corner oil passages.

    It's common to see "prints" of the old gasket or even corrosion in the "dead" spaces. This is usually pretty harmless and you can create more problems than you solve if you get too obsessive about cleaning up these areas.

    Also, depending on which version of the OEM head gasket you end up with (do not even consider aftermarket), you may not need that square o-ring around the center tunnel. Later versions just cover this area with gasket; earlier versions were open here so the o-ring formed the seal.
    1983 GS850G, Cosmos Blue.
    2005 KLR685, Aztec Pink - Turd II.3, the ReReReTurdening
    2015 Yamaha FJ-09, Magma Red Power Corrupts...
    Eat more venison.

    Please provide details. The GSR Hive Mind is nearly omniscient, but not yet clairvoyant.

    Celeriter equita, converteque saepe.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •