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Thread: Potential Group Purchase - Wiseco GS650 741cc pistons

  1. #341
    Join Date
    Mar 2016
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    East Wallingford Vermont
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    A couple of gaskets I have here to measure, a new factory Hayabusa MLS is 1mm over the bore size.
    A factory Mitsubishi Evo MLS is 1.2mm over the bore size, Mitsu does not offer oversize head gaskets so I expect this has room for .5mm overbore piston sizes.
    I would presume that the 1mm over size John recommends is the proper thing for us to do.
    Regards, Charlie
    '66 Hustler cafe build
    '78 GS 750E sitting
    '79 GS 550 ex racebike soon to be a 740
    '83 GS 550ES with a 5-11 swap
    '75 Ducati Sport, stock and will remain so

  2. #342
    Join Date
    Aug 2012
    Location
    Columbus, Ohio
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    I actually went back down to the shop late last night and measured the Wiseco 65mm 740cc NOS gasket that I have, and it is for 65mm pistons, and measuring through the plastic wrap, this gasket bore is only 65.175mm bore or something close like that...


    I like the idea of having it as close as possible to the bore, less volume means higher compression, and I feel that it will make the engine less efficient if there is a .8mm or so crevasse there for air and fuel to hide in, away from the flame front.
    I want to look into this a bit further and see if there are any drawbacks to having the gasket bore closer to the edge of the cylinder bore. Obviously if there is even the slightest taper at the top of the bore, this will necessitate the gasket bore being slightly larger, which the Wiseco NOS gasket dimension implies.

    '77 Suzuki GS750 920cc 4-1, Sun rims, GS1100E swinger, fork mods, Fox Factory Shox, Ninja/CBR900RR discs
    '74 Rickman VR250 MX
    '99 Kawasaki KDX220 rugged terrain ripper
    PROJECTS:
    '77 Rickman CR900 GS1000-1105cc roadracer Yoshi race cams Yoshi 4:1, 89 GSXR1100K fork, 310mm discs, Fox Factory Shox
    '79 GS425 489cc/GS850 sleeves, megacycle cams, GS500 fork, 310mm CBR disc, DID rims, GS1100E swingarm, Fox Factory Shox
    '77 GS550 GS650-740cc top end, CBR900RR/Ninja brake, Fox Street Shox

  3. #343
    Join Date
    Aug 2012
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    Columbus, Ohio
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    2,476

    Default Latest word on the gasket options

    I heard back from John, and apparently the price he quoted was for the easier method of affixing the multiple layers of spring shim steel together, using external tabs that are basically press riveted together. I am picturing this as being several extra tabs of material hanging out past the head where they are pressed together or riveted with a pressing action.

    Apparently the style of the GS1100G gasket that I sent him photos of uses a bushed fit, where all of the head stud and bolt holes aside from the oil passage holes are cut undersized pm the outer layers and oversized holes slightly in the middle layers, and then the very undersized bottom layer is pressed through and folded over the inner layers and folded back like a rivet, securing all the layers together. The 1100G MLS gasket has this on all of the stud holes except the outside corner oil passages (for maximum sealing) and the 4 studs by the cam chain tunnel have the pressed through rivet "Bushed" method only around 65% of the stud, as to not distort the metal nearest the center cylinders inside areas, since those studs are closer.

    It sounds like this method will probably bump the price up, but I am very much for proceeding with that route vs the external tabs and rivets.

    I will get back to him on asking how much the price will be affected. Doesn't sound like a ton but possibly slight hike, I hope this is alright with everyone.




    Quote Originally Posted by John@gasketstogo}
    [EMAIL="inquiries@gasketstogo.com"
    Gaskets-To-Go <inquiries@gasketstogo.com>[/EMAIL] [*][*]Today at 4:46 AM


    Message body

    Hi Chuck,

    This appears to be what we term bushing, when part of one sheet is folded over another to hold them together and/or form a seal. Assume those are all the bolt holes?

    The price I quoted was for a MLS with external riveting. If these need to be bushed like that it could affect the price.

    Please let me know if we can external rivet (several tabs on the outside with a rivet through them to hold all sheets together.

    Regards,

    John




    EDIT - I emailed him this sketch, and also asked if we could possibly use the OEM bushing technique on the 7 holes with an arrow and a B in them, and then use the tab and rivet technique in the center as a substitute for the 4 inner studs that the factory only partially crimped over or bushed, as they are closest to the compression sealing portion of the head gasket and Suzuki apparently skipped the inner portion of the head stud hole crimping or bushing in order not to compromise the sealing of the cylinder pressure whatsoever.



    I have a VW Diesel head gasket on my wife's rabbit pickup that John made several years ago. I think it is the tab/rivet style. I will have to have a look under the hood to see if I can spot the tab and rivet external technique.
    Attached Images Attached Images
    Last edited by Chuck78; 03-19-2017 at 03:24 PM.

    '77 Suzuki GS750 920cc 4-1, Sun rims, GS1100E swinger, fork mods, Fox Factory Shox, Ninja/CBR900RR discs
    '74 Rickman VR250 MX
    '99 Kawasaki KDX220 rugged terrain ripper
    PROJECTS:
    '77 Rickman CR900 GS1000-1105cc roadracer Yoshi race cams Yoshi 4:1, 89 GSXR1100K fork, 310mm discs, Fox Factory Shox
    '79 GS425 489cc/GS850 sleeves, megacycle cams, GS500 fork, 310mm CBR disc, DID rims, GS1100E swingarm, Fox Factory Shox
    '77 GS550 GS650-740cc top end, CBR900RR/Ninja brake, Fox Street Shox

  4. #344
    Join Date
    Dec 2016
    Location
    Shropshire
    Posts
    14

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    Hi Chuck. I will take 2 gaskets at the $80 price, but I would need them shipped to the U.K as you know. I am planning on getting the block decked, so maybe I should take two gaskets at a suitable thickness ( 0.8mm or 0.9mm ). If you think a different thickness would be good as a back up, I will go with your choice and happy to go with general view on which gasket make up is best. But put me down for 2 in the first buying group and let me know when you need paying and I will paypal the funds to you.

  5. #345
    Join Date
    Nov 2012
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    socal
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    chuck ... i'm still good for 2 gaskets. .8mm and .9mm. ready to paypal....just say the word.
    Last edited by frankenwabbit; 03-20-2017 at 12:18 PM.

  6. #346
    Join Date
    Dec 2016
    Location
    Shropshire
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    14

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    Chuck, reading your info again and if i have understood correctly, it seems as if i should go for one at 0.8mm and the other at 0.9mm, as then I can either run the block as it is, or run with a zero decked block.

  7. #347
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    Aug 2012
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    Columbus, Ohio
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    Decision needed here - John says it's $5 extra to have the bushed style stud holes to rivet the gasket together, or else we will have external tabs protruding out from the head/block where the gasket is riveted together externally.

    I think I'd prefer the bushed hole style where there are no external protrusions, but he did not answer my question as to whether or not they could do the 4 inner holes in a 60% bushes method as the OEM 4 center studs are done. I will check back with him on that. He didn't confirm the estimate, but his original estimate was 5-24 gaskets approximately $80 each, externally riveted. So this would likely be $85 each with the bushed holes self-riveting the layers of gasket together, or $80 with external tabs and rivets.

    Your thoughts???

    Quote Originally Posted by John@GasketsToGo.com
    Hi Chuck,

    Sorry for the delay in getting back to you.

    To bush those bolt holes like that would add $5 to each gasket.

    If you place an order for 20 I would be happy to send you one with external rivets first for your approval before mfg and sending the remaining units. If the only function is to hold the gasket together I don't think there would be any difference.

    Regards,

    John

    '77 Suzuki GS750 920cc 4-1, Sun rims, GS1100E swinger, fork mods, Fox Factory Shox, Ninja/CBR900RR discs
    '74 Rickman VR250 MX
    '99 Kawasaki KDX220 rugged terrain ripper
    PROJECTS:
    '77 Rickman CR900 GS1000-1105cc roadracer Yoshi race cams Yoshi 4:1, 89 GSXR1100K fork, 310mm discs, Fox Factory Shox
    '79 GS425 489cc/GS850 sleeves, megacycle cams, GS500 fork, 310mm CBR disc, DID rims, GS1100E swingarm, Fox Factory Shox
    '77 GS550 GS650-740cc top end, CBR900RR/Ninja brake, Fox Street Shox

  8. #348
    Join Date
    Aug 2012
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    Columbus, Ohio
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    Quote Originally Posted by 5hrine View Post
    Chuck, reading your info again and if i have understood correctly, it seems as if i should go for one at 0.8mm and the other at 0.9mm, as then I can either run the block as it is, or run with a zero decked block.
    Running the block almost zero decked (piston down in hole .003" with base gasket torqued) with a .8mm gasket would be the minimum clearance one would need. This gives you a .033" squish band (TDC piston to head clearance) as Old Colt the veteran race engine builder is shooting for.

    In my hot rof car days, I was under the working impression from other veteran builders that you wanted to shoot for .039"-.045" squish band. This is on a water cooled V8 engine. I was going to shoot for that myself.

    Another note - if you are planning to optimize your quench distance down to .030" or .040", you will be moving the cams closer to the crank, which is going to alter your cam timing quite a lot, and may require slotting the cam sprockets to dial them back in where you want it. This requires a runout type micrometer pointer gauge and magnetic base (I hit one at garbkr Freight tgat works well enough), a TDC piston stop device, & a cam degree wheel.

    Running a very lightly skimmed / milled block and head and a 1.0mm or 1.1mm gasket will keep timing fairly close to where it was when the bike left the factory. This is another grey area, as factory timing tolerances varied quite a lot - 1 area where Suzuki skimp ed on assembly tolerances.

    It is best to at least check the cam timing lobe centerlines regardless. 110 Int / 110 exhaust or so is better for lots of high end power. 104 intake / 106 exh builds lots of mud range street torque. Big lift cams can't advance the timing as much due to piston to valve clearance issues.

    Any alteration of the cam timing requires checking piston to valve clearances, as the pistons and valves chase each other closely thoughout parts of the crankshaft rotation. You don't want them too close or else a missed shift at redline could start to float the valves and you might have some harsh contact there and bend a valve.

    So what I am saying here is that if you zero deck and run a .9mm gasket, or run close to a zero deck and a .8mm gasket, you are definitely going to want to check the cam timing or at least piston to valve clearance (you can see thus through the spark plug hoke but pro builders do a clay mockup on the piston and assemble the engine and rotate, then pull back apart).

    So if you are considering the thinner gasket and a zero deck, you definitely need to be aware that you should be checking your cam timing and piston to valve clearance.

    If you run a lightly resurfaced head and block or stock, a 1mm gasket, your timing will be closer to factory soec, but again, the timing could be several degrees off at factory built conditions even, so it's best to get a degree wheel, runout gauge micrometer, & a TDC piston stop and read the Web Cams article on cam degreeing. Time consuming but not too difficult. A custom pointer on the runout gauge may need to be fabricated to clear the cam lobe to get on the bucket properly if you want to get the most accurate valve lift measurements.

    Also just wanted to make sure you all realized the .8mm gasket may compress down to just a touch over .7mm, and about .76mm is around .030" which Old Colt was shooting for in total quench height, so he'd need to have his piston down in the hole at TDC about .04mm or approximately .003", which is just short of a zero deck.


    Please make sure you are all aware of this info before we commit to ordering your thickness requested.


    As to the bushed holes vs external riveted tabs, if there is any question of the 4 inner stud holes being able to be only half bushed (half of the circle riveted back on itself, not the half closest to the cylinder bores), then maybe we should lean towards the external rivet method and save $5/each

    '77 Suzuki GS750 920cc 4-1, Sun rims, GS1100E swinger, fork mods, Fox Factory Shox, Ninja/CBR900RR discs
    '74 Rickman VR250 MX
    '99 Kawasaki KDX220 rugged terrain ripper
    PROJECTS:
    '77 Rickman CR900 GS1000-1105cc roadracer Yoshi race cams Yoshi 4:1, 89 GSXR1100K fork, 310mm discs, Fox Factory Shox
    '79 GS425 489cc/GS850 sleeves, megacycle cams, GS500 fork, 310mm CBR disc, DID rims, GS1100E swingarm, Fox Factory Shox
    '77 GS550 GS650-740cc top end, CBR900RR/Ninja brake, Fox Street Shox

  9. #349
    Join Date
    Aug 2012
    Location
    Columbus, Ohio
    Posts
    2,476

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    John is asking me now if we want to do an embossed MLS gasket, or if we just want a standard flat gasket as the OEM Suzuki MLS gaskets are. Does anyone have any feedback? The flat gasket would be cheaper. The embossed gasket I am assuming would be better, but he says he would need to make one prototype to send it to me first for approval. I know there is at least one member waiting for a head gasket very eagerly as they are rebuilding their bike right now. The standard style like Suzuki uses is the more affordably priced option. Can anyone give me a vote either way?

    '77 Suzuki GS750 920cc 4-1, Sun rims, GS1100E swinger, fork mods, Fox Factory Shox, Ninja/CBR900RR discs
    '74 Rickman VR250 MX
    '99 Kawasaki KDX220 rugged terrain ripper
    PROJECTS:
    '77 Rickman CR900 GS1000-1105cc roadracer Yoshi race cams Yoshi 4:1, 89 GSXR1100K fork, 310mm discs, Fox Factory Shox
    '79 GS425 489cc/GS850 sleeves, megacycle cams, GS500 fork, 310mm CBR disc, DID rims, GS1100E swingarm, Fox Factory Shox
    '77 GS550 GS650-740cc top end, CBR900RR/Ninja brake, Fox Street Shox

  10. #350
    Join Date
    Aug 2012
    Location
    Columbus, Ohio
    Posts
    2,476

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    It looks like the embossed gasket with bushed holes will run around $85, & the flat gasket (like OEM Suzuki MLS) will run $66 or so. he is going to get back to me tomorrow or Monday on more exact pricing.
    For high performance applications, it seems as if the embossing will really help seal the cylinders much better, & should give extra insurance against oil leaks on the tunnel area and oil pressure passages on the outside 4 corners. This seams to me the way to go. The metal will be pressed upward on the outer layers of the gasket to further add to the spring effect to seal the cylinder & oil passages better. OEM just used a plain flat gasket, no embossing, but that was 1982 technology.

    Please give me your opinions.

    Thank you,

    Chuck

    '77 Suzuki GS750 920cc 4-1, Sun rims, GS1100E swinger, fork mods, Fox Factory Shox, Ninja/CBR900RR discs
    '74 Rickman VR250 MX
    '99 Kawasaki KDX220 rugged terrain ripper
    PROJECTS:
    '77 Rickman CR900 GS1000-1105cc roadracer Yoshi race cams Yoshi 4:1, 89 GSXR1100K fork, 310mm discs, Fox Factory Shox
    '79 GS425 489cc/GS850 sleeves, megacycle cams, GS500 fork, 310mm CBR disc, DID rims, GS1100E swingarm, Fox Factory Shox
    '77 GS550 GS650-740cc top end, CBR900RR/Ninja brake, Fox Street Shox

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