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Thread: Potential Group Purchase - Wiseco GS650 741cc pistons

  1. #501
    Join Date
    Aug 2012
    Location
    Columbus, Ohio
    Posts
    3,601

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    If shipping weren't so far, I'd be looking for a good spare 650 top end and carbs. But I'd urge you to stick with it & use the winter to get the bike freshened up & do the top end swap.

    '77 GS750
    920cc, 4-1, GS1100E swinger, 18"rims, Fox Factory Shox, twinpot dual disc, VM29's, Yoshi cams
    '99 Kawasaki KDX220 rugged terrain ripper
    '74 Rickman VR250MX
    PROJECTS:
    '77 Suzuki PE250 Pure Enduro trail beast, ported, Wiseco, TüBliss, Fox Factory Shox/RaceTech
    '76 Rickman CR GS1000-1120cc roadracer, Yoshi cams&4-1, RF900R fork, Works ProRacers
    '79 GS425 489cc, GR650 cams, GS650 fork, twinpot discs, DID rims, GS1100E swinger, Fox Factory Shox
    '77 GS550 650-740cc susp/brake mods

  2. #502
    Join Date
    May 2018
    Location
    Vancouver, BC
    Posts
    27

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    It's not about giving up easily....

    I want to be on the road next spring. I'm also not looking for 550/650 conversion. I have a GS650G. Actually 2 engines. Both cylinders needs boring, because they were both sitting for ages and the previous owners didn't care.
    In order to get the engine back to life, I need boring. With boring I need oversize pistons. Just boring and oversize pistons(if I even get oversize pistons) are CAD1000+. Plus gaskets, tires and a million other things. So I'm very quickly in a price range, where I get a decent Honda from the 90's or maybe early '00s that will last forever without a lot of maintenance.

    Don't get me wrong. I would love to finish this project. But I want to ride and go on adventures. And because I don't have a lot of many to throw out of the window I need to prioritize. I hope that makes sense.
    Vancouver, BC
    Suzuki GS 650G '81

  3. #503
    Join Date
    Jun 2008
    Location
    New Buffalo, Michigan 49117
    Posts
    5,718

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    Quote Originally Posted by Berti View Post
    It's not about giving up easily....

    I want to be on the road next spring. I'm also not looking for 550/650 conversion. I have a GS650G. Actually 2 engines. Both cylinders needs boring, because they were both sitting for ages and the previous owners didn't care.
    In order to get the engine back to life, I need boring. With boring I need oversize pistons. Just boring and oversize pistons(if I even get oversize pistons) are CAD1000+. Plus gaskets, tires and a million other things. So I'm very quickly in a price range, where I get a decent Honda from the 90's or maybe early '00s that will last forever without a lot of maintenance.

    Don't get me wrong. I would love to finish this project. But I want to ride and go on adventures. And because I don't have a lot of many to throw out of the window I need to prioritize. I hope that makes sense.
    It's ok Dude. I know I go through the economy of restoring any bike before purchase. Even have a GS650E under consideration, that might have to include engine boring and camshaft replacement. It does look kinda high priced to me right now.
    Buying a vintage bike in very good running condition is just good sense.
    Pistons and cams are available for select popular vintage bikes, I know these include the GS1000 and some Kawasaki GPz bikes including the 550cc. Some vintage GSXR years are supported some are not.
    Last edited by Buffalo Bill; 11-25-2019 at 05:29 PM.
    "Only fe' collected the old way, has any value." from His Majesty O'Keefe (1954 film)
    1982 GS1100G- road bike, body, seat and suspension modded
    1990 GSX750F-(1127cc '92 GSXR engine) track bike, much re-engineered
    1987 Honda CBR600F Hurricane; hooligan bike, restored

  4. #504
    Join Date
    Oct 2018
    Location
    SE South Dakota
    Posts
    5

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    If more get on board, I'm highly interested.
    Also, has anyone considered instead of removing material from the 550 case to fit the 650 cylinders, to remove the individual cylinders and lathe the outer bottom of each cylinder to fit? Doing this route would eliminate potential case shavings from getting dropped into the bearings/bottom end. Just an idea I had.
    79 KZ400ltd
    79 GS550e
    82 KZ750e
    2011 Z1000

  5. #505
    Join Date
    Aug 2012
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    Columbus, Ohio
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    So this big bore 550/650-740cc mod just got a lot cheaper... I had seen these last year on eBay, but being that the Wiseco are higher compression and able to run aftermarket camshafts (deeper valve pockets), I hadn't said much about the budget alternative, in hopes of others doing a second group purchase of these pistons.

    But now it seems that getting another group buy together is a little lacking, I'll just offer up this option:

    https://www.cruzinimage.net/2018/12/18/81-83-suzuki-gs650-740cc-bigbore-pistons-kit-65mm-piston/





    81-83 SUZUKI GS650 740cc BIGBORE PISTONS KIT 65mm PISTON

    -DESCRIPTION-◆10-GS650BB◆
    *81-83 Suzuki GS650 Bigbore pistons kit with Head Gasket
    Aftermarket
    Piston size: 65mm( 3.00mm Oversize )
    Head gasket: Bore size is 68mm
    *Set includes: pistons, pins, clips,rings and head gasket
    Note: Cylinder boring required
    These pistons are aftermarket.different design from of the Suzuki genuine pistons





    All that for $200 shipped to the USA! Japan seller, but made in Taiwan iirc. I have a set of 870cc 70mm pistons for GS750/850 applications, and they appear to be every bit as good of quality as the OEM Suzuki ART Pistons, and the first stuff this company was offering was old Honda CB big bore kits years ago, and those things have been proven to hold up as good as OEM and be of reputable quality... Highly advocated amongst the SOHC Honda Fours crowd. The rings I might suspect aren't as good as OEM, but maybe they will hold up as well as OEM anyways?

    You will still need to run a thicker custom base gasket with these unless the head gaskets are thicker than stock (compressed thickness) by at least .005" or more, but that's the easiest part. Cometic can custom make base gaskets for cheap if you tell them GS550 base gasket with GS650 sleeve sizes, and in custom thickness (refer back in this thread for actual thickness needed). Or if Cometic has a GS650E gasket on file, different than the 650G, it is exactly what is needed but in a slightly thicker gasket material. Perhaps the GS650G gasket method may be better though, as a thicker 550/650E style base gasket will leave the rear corner oil feed passage egg-shaped o-rings less compressed than with stock base gasket. Suzuki_Don and others who did the custom thicker base gasket I believe had the 650G style and let the egg shaped oil pressure o-ring seat against the bottom of the paper gasket, which would have it compressing .020" more than it was intended. So A LOT MORE compression vs slightly less compression of this oil pressure o-ring are the two options if you are going thicker base gasket. The verdict is up for debate.

    With the cast piston option above, I'd be shaving the head slightly, and running just enough thickness of head and base gaskets to give the piston adequate clearance, in order to maximize the squish band and slightly bump up compression ratio...
    Attached Images Attached Images

    '77 GS750
    920cc, 4-1, GS1100E swinger, 18"rims, Fox Factory Shox, twinpot dual disc, VM29's, Yoshi cams
    '99 Kawasaki KDX220 rugged terrain ripper
    '74 Rickman VR250MX
    PROJECTS:
    '77 Suzuki PE250 Pure Enduro trail beast, ported, Wiseco, TüBliss, Fox Factory Shox/RaceTech
    '76 Rickman CR GS1000-1120cc roadracer, Yoshi cams&4-1, RF900R fork, Works ProRacers
    '79 GS425 489cc, GR650 cams, GS650 fork, twinpot discs, DID rims, GS1100E swinger, Fox Factory Shox
    '77 GS550 650-740cc susp/brake mods

  6. #506
    Join Date
    Aug 2012
    Location
    Columbus, Ohio
    Posts
    3,601

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    One big argument I see here for the WIseco piston vs these, is that these state that they're a different design than the OEM pistons. I see waaaayyyy less quench area there, perhaps they are more like the 550 pistons in this regard? I'd really like to have a set of these in my hands to see what they are all about.

    Perhaps that is a stock image and not actually the GS650 piston kit? Huge difference in dome/quench design, so I'm guessing yes. Comparison:



    VS

    Last edited by Chuck78; 05-14-2020 at 12:35 AM.

    '77 GS750
    920cc, 4-1, GS1100E swinger, 18"rims, Fox Factory Shox, twinpot dual disc, VM29's, Yoshi cams
    '99 Kawasaki KDX220 rugged terrain ripper
    '74 Rickman VR250MX
    PROJECTS:
    '77 Suzuki PE250 Pure Enduro trail beast, ported, Wiseco, TüBliss, Fox Factory Shox/RaceTech
    '76 Rickman CR GS1000-1120cc roadracer, Yoshi cams&4-1, RF900R fork, Works ProRacers
    '79 GS425 489cc, GR650 cams, GS650 fork, twinpot discs, DID rims, GS1100E swinger, Fox Factory Shox
    '77 GS550 650-740cc susp/brake mods

  7. #507
    Join Date
    May 2018
    Location
    Vancouver, BC
    Posts
    27

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    Well, I bought these pistons and this is the result...

    https://www.thegsresources.com/_foru...23#post2651323
    Vancouver, BC
    Suzuki GS 650G '81

  8. #508
    Join Date
    Aug 2012
    Location
    Columbus, Ohio
    Posts
    3,601

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    Quote Originally Posted by Berti View Post
    Well, I bought these pistons and this is the result...

    https://www.thegsresources.com/_foru...23#post2651323
    Awww man that SUCKS! They basically sold you a hemi head domed piston nearly identical to the stock 77-79 GS750 piston...
    I would DEFINITELY be contacting them to complain, at least so they pull them and don't screw over anyone else... Unless perhaps they actually did mix up and send you GS750 65mm stock hemi pistons vs big bore GS650 65mm closed chamber head pistons...
    MAJOR BUMMER...
    But... an 80+ 8v GS550 head may potentially work on that piston with minor dome machining around the perimeter. There's no way you could machine that big hemi dome down to the 650 dome shape/size, you'd cut through to the back side...

    '77 GS750
    920cc, 4-1, GS1100E swinger, 18"rims, Fox Factory Shox, twinpot dual disc, VM29's, Yoshi cams
    '99 Kawasaki KDX220 rugged terrain ripper
    '74 Rickman VR250MX
    PROJECTS:
    '77 Suzuki PE250 Pure Enduro trail beast, ported, Wiseco, TüBliss, Fox Factory Shox/RaceTech
    '76 Rickman CR GS1000-1120cc roadracer, Yoshi cams&4-1, RF900R fork, Works ProRacers
    '79 GS425 489cc, GR650 cams, GS650 fork, twinpot discs, DID rims, GS1100E swinger, Fox Factory Shox
    '77 GS550 650-740cc susp/brake mods

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