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Thread: Custom Gaskets??

  1. #1
    Join Date
    Sep 2004
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    2,982

    Default Custom Gaskets??

    Grey Canadian gasket sealant gooped on both sides of a hommade cardboard gaskey for Base Gaskets in a snowmobile engin\e?? I was looking for a new motor for a old sled im fixing. I find one (a motor) and the kid tells me he made gaskets from cardboard and just used silver permatex gasket maker from canadian tire on each side and stuck it together. Whatya think guys sound good>>>????

  2. #2
    Join Date
    Dec 2008
    Location
    N.E. oHIo
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    465

    Default

    I once made water pump gaskets for a 283ci Chevy out of a phone book cover.
    They were goin' strong when I sold the car 2 years later.


    Rex

  3. #3
    Join Date
    Dec 2008
    Location
    Prince George BC
    Posts
    196

    Default Yikes!!

    Sounds like a real hack job!! If he is too cheap to buy a proper base gasket I can only imagine what he did inside the motor. If the base gasket fails air can be drawn into the crankcase and thereby lean out the mixture, which means it will run reallllly good just before it cooks a piston!
    Two strike motors are really quite fussy.
    All this is in glaring contrast with the most forgiving motor ever built, the good ole 283 SBC. Make no mistake there can be ABSOLUTELY no comparison between these 2 motors!
    jmho as I'm just an automotive machinist who loves to fix this stuff (sleds) after guys have their buddies giving such sound advice as using cardboard and/or anything purchased from Cambodian Tire.
    al
    Last edited by The Fixer; 01-08-2009 at 01:56 PM.

  4. #4
    Join Date
    Feb 2004
    Location
    South Arkansas, USA
    Posts
    82

    Default Custom Gasket

    Thin cardboard and/or heavy brown paper were standard gasket materials when I was growing up ( 1940's - early 1950's) but we didn't have the modern gasket goops to smear on it. We used shellac, paint, or (when we could afford it) Permatex. Couldn't work on anything without it. I still have my gasket hammer (4 oz ball peen) from those days. Various forms of paper are still used for gaskets but it is now so treated and coated that it may not be easily recognized as such.

    Regarding late model 2 cycle engines, many don't even use gaskets between crankcase sections but instead rely on machined surfaces with sealant in the joints. Seems to work very well.

  5. #5
    Join Date
    Sep 2004
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    2,982

    Default Nice

    I thought perhaps it would be OK BUT i can see a sucking leak developing into a blown piston head ect. I am putting together a old 1979 Yamaa exiter and am installing a srv engine into it,. perhaps i can find a better example.

  6. #6
    Join Date
    Nov 2008
    Location
    Kingman Arizona
    Posts
    1,736

    Default Gaskets?

    Quote Originally Posted by madman
    I thought perhaps it would be OK BUT i can see a sucking leak developing into a blown piston head ect. I am putting together a old 1979 Yamaa exiter and am installing a srv engine into it,. perhaps i can find a better example.

    Cardboard and RTV? Geez! First of all, it might be a good idea to know what the composition and thickness of the original gaskets were. A lot of gaskets are made of pressed cellulose (fiber) but some specialized gaskets have a metal matrix molded in to strengthen them. Then, there's the matter of the thickness of the gasket. two-stroke engines rely on ports in the walls of the cylinders to time their intake and exhaust, using the wrong gasket can upset this timing and result in a loss of power. Too thin, or too thick, it will change the height of the ports in the cylinders.

    RTV on gaskets? According to the 3M Company, GM, Ford, Chrysler, and a bunch of other manufacturers, using RTV sealer on gaskets is a huge No-No... RTV (Room Temperature Vulcanizing) sealer is meant to be used in place of a gasket, not with a gasket. True, in some cases RTV is applied to the corners of some gaskets to aid sealing the joints, but you don't smear the whole gasket with it. (For one, it makes the gasket slippery, and it has a tendency to squeeze out) You might get away with it a time or two, but it ain't right.

    RTV, used properly, is designed to be applied to two machined, or stamped surfaces, and assembled while it's still "wet". The sealer "skins over" in 8-10 minutes, is usable in an hour and completely cures in 24 hours.
    Letting RTV "skin over" will cause it to split like a grape when the parts are assembled....(Yeah, I know, the guys on "HorsepowerTV" do it all of the time...but their writers don't know any better.

    Basically it's designed to be applied, and cure in place, bonding to both parts, forming a silicon rubber gasket....
    No good deed goes unpunished.

  7. #7
    Join Date
    Sep 2004
    Posts
    2,982

    Default Sounds Pretty CHEESY

    Yes that motor is sounding pretty cheesy bUT i need one for my 1979 vintage exiter, i am going to sudbury to buy it 10 hour there and back drive and will stuff it into my sled and see what happens. I am thinking of some new equipment for my new shop (just finishing it) and will be doing engines cylinder boring honing and ??? crankshafts, I have done a crank years ago ducati . i remember needing a 50 ton press to get the large crankpins out. Scary, Had a small pin on a suzuki 1100 crankshaft fly out of a press many many years ago and it actually flew across the shop wall and went through a cinder block block scared the crap outa all mt friends standin around watching. LOL lucky no one died.

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