uh-oh with gasket maker...?

Discussion in 'Motorized Bicycle General Discussion' started by bronson9, Sep 5, 2010.

  1. bronson9

    bronson9 New Member

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    Hi all,

    This is my first build and i have a 2-stroke 80cc bgf, 200mi, runs great. I have worn out the gasket that goes between the muffler and the cylinder so oil is leaking out through that space. I bought some Permatex* High Temp Red RTV Silicone Gasket Maker from a local parts store and just finished (about 10 mins ago) applying the silicone i bought to the muffler and attatching it back to the engine.

    When i read through the instructions again to re-check how long it took to cure, I noticed the last line said...

    Note: Not recommened for use on head gaskets or parts in contact with gasoline.

    :( SO... I'm worried I have messed up. I rode my bike to the part store to show the clerk specifically what I was talking about and he directed me to the High temp red rtv silicone gasket maker...

    I'm just wondering if anyone has ever done the same with good or poor results,
    OR
    if someone knows that I have just plain messed up and should by no means fire my engine until i pull...or sand?.. my silicone gasket off..please please let me know

    Thanks very very much to anyone who can help
     
  2. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    You should be fine, it's not really "in contact with gasoline" and the pressure there is much lower than the head gasket. Being silicone, it probably won't burn away either.
     
  3. 2door

    2door Moderator
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    You'll see that warning on most, if not all silicone based gasket sealers/compounds. I wouldn't rely solely on a gasket maker/sealer but instead would suggest you make a new gasket from the proper gasket material. You auto parts store should have it. I like to use a heavy gasket material on the exhaust side, preferably 1/8" thick and I don't use silicone or any other sealer. Just torque the flange fasteners correctly and retorque once again after the engine has reached operating temperature.
    Good luck.
    Tom
     
  4. bronson9

    bronson9 New Member

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    thank you very much for responses I really appreciate it.

    happy riding!
     
  5. Goat Herder

    Goat Herder Gutter Rider

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    The silicone gasket will scratch of easily with your finger nails. You should have a copper or aluminum gasket there. Until you get a good gasket and make sure your exhaust flange is straight you'll get no dice.

    A copper or aluminum gasket will expand correctly with the heat of the exhaust and stay sealed. Better than a paper gasket.

    I use the Permatex® Ultra
    Copper® High-
    Temp RTV Silicone
    Gasket Maker
    Item # 81878
    Exhaust manifolds/
    headers, valve
    covers, oil pans,
    timing covers,
    thermostat housing,

    http://www.permatex.com/documents/GasketMakerSelector.pdf


    The exhaust is tough to seal with out the right gasket. The cheap china mufflers take nothing to warp the flange. Put a strait edge on it and check.

    This product works perfect only when each surface is flush [not warped]. Other wise a gasket has to be used.

    It takes very little of this product to do the job.

    I have a carb manifold with no gasket just the said stuff never leak in 2000 miles. Something always rattles loose on a china. Having a small tube of this for a needed field repair can be nice. [when the cheezy china gaskets fall apart.]

    All this being said Make better gaskets than the stock gaskets and that's a great approach.
     
  6. jakrabit2010

    jakrabit2010 New Member

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    I have a question??

    Can you use the High-Temp Red RTV Silicone Gasket Maker on Carburetor bowls to reseal them, I just broke down all four of my carbs. so I could clean them out and ready for next year because it ran like crap this year they where so nasty on the inside.

    Now I am ready to put them back together and don't know wheather to completely trust the old rubber gaskets or not!!
     
  7. Nougat

    Nougat New Member

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    I wouldn't use sealer on a carb. Even the gasoline resistant sealer I used between my carb and intake got gummy and fell off.
     
  8. 2door

    2door Moderator
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    Normally I always agree with Nougat's advice but in this case I'll have to say I do not.
    Most silicone based gasket sealers will advise against use where it will come into conatct with gasoline. That's why we recommend a product made for the purpose. The carburetor to intake manifold mating area requires some form of sealer to assure againt vacuum leaks. Even with an 'O' ring inside the carb there needs to be sealer used. The metal to metal connection will not prevent air leaks into the manifold downstream of the carb...and that you don't want. Read the label of the gasket sealers and choose one that will stand up to gasoline. Sorry Noug...:)
    Tom
     
  9. Nougat

    Nougat New Member

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    For the record, I went in with sealing my carb to the intake with that in mind, and sought out an appropriate sealer. I selected this:

    Amazon.com: Permatex 80060 #97 High Tack Super Gasket Sealant - 1.75 oz.: Automotive "Resists gasoline, oil, antifreeze, axle lube"

    Later on down the road, I decided to buy a #68 jet from SBP. Knowing that I'd need to remove the carb from the intake, I decided to also buy a three-pack of their Viton o-rings, just in case.

    And it was a good thing, too, because when I took the carb off the intake, the 97b was easily wiped away, the consistency of old jelly, and a little bit slimy. My carb is now attached with just the o-ring, and it's doing pretty well.

    Perhaps I am wrong to paint all claims of gasoline resistance with the same brush, but Permatex is a well known brand, and I'd expect "gasoline resistant" to mean a bit more than what I got. I can definitely say don't use Permatex 97b.

    If you've got a better specific product suggestion, I'm all ears.
     
  10. BarelyAWake

    BarelyAWake New Member

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    I haven't much of a suggestion beyond that 'Seal-All' does seem to hold up... but judging from the above I'd say it's another example of "gasoline resistant" just not being the same as "alcohol resistant" and sadly, few products are taking this into account despite the fact that everywhere ya go these days we're plagued w/egas *shrug*

    For the exhaust, I'd defo agree that making your own metallic gasket from aluminum or copper is the way to go, or ya could just buy one premade like the one Sick Bike Parts offers.

    ...and for the intake manifold makin' one out of a quality paper gasket material is easy-peasy, however another solution not so common anymore is leather. Out of gasket material & tearing my last gasket, I chopped up a leather work glove to make a new one & I gotta say it's by far my favorite technique now, that gasket seems infinitely reusable - not easily damaged by just messin' with the intake manifold and seals really well (^)

    I try to never use any sort of "insta-gasket" goop on my builds, while a commonplace solution in many applications & even shops tend to use it - I can't help but to think it a bit of a cheat TBH and if yer prone to tinkerin' - takin' apart your build constantly to improve it or w/e, it can make life a pain. If the mating surfaces are made perfectly flush by refacing the intake and exaust flanges (a good flat file & some patience) there's really no need for any sorta sealant, ideally it's a "gap filler" and if you don't have any gaps, you'll not need it.

    Sadly, with the NT & speed carbs and the stock intake, particularly the chrome one, there's little that can be done to insure a good mating surface - there I'd hafta agree w/Tom, just a touch of goop will help prevent a vacuum leak. I'd prefer to use somethin' less "brutal" than 'Seal-All' as it is a glue of sorts... but now we're back to alcohol resistance and the lack of a suitable product *shrug* While 'Seal-All' isn't truly alcohol resistant, being a "glue" instead of just a sealant it seems that when it breaks down it doesn't get to the "slimy & useless" stage, it becomes much like what the permatex whas supposed to stay like *shrug*
     
    #10 BarelyAWake, Nov 23, 2010
    Last edited: Nov 23, 2010
  11. 2door

    2door Moderator
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    The chrome plated intakes can be problematic when it comes to getting a good seal. I recommend a good sanding to 'kill the gloss' and rough up the surface so whatever sealant you choose can get a 'bite' . I like to use plumber's sand cloth and I prefer the open weave type. It comes on a roll and is about an inch wide. It has an aggressive abrasive that will rough up the chrome surface. As for the carburetor, another plumber's tool works well to clean and rough up the inside of the carb throat where it attaches to the intake. These are called 'fitting brushes' they come in sizes corrosponding to copper tube sizes (1/4, 3/8, 1/2" etc.) They are round, stiff bristled wire brushes made for dressing the inside of copper fittings prior to soldering. A 5/8 or 3/4 brush will fit the carburetor throat. Warning: Clean stuff after sanding; carb and manifold.
    As for ease of disassembly and Seal-All. Like Geoff said, it is a 'glue' of sorts and holds well but I've found a quick firm twist will break the seal and allow disassembly without resorting to some kind of nasty solvent to break the grip. He is also correct about the resistance to certain government mandated additives to gasoline. The alcohol has proven to be the bain of classic car owners for several years now. It will eventually attack rubber fuel lines, fuel pump diaphrams and carburetor parts that were made for use with gasoline, not alcohol. It will be interesting to see if/when manufacturers of products like Permatex and Seal-All will address the alky problem. As yet I've only seen fuel line (hose) and fuel system parts for late madel cars available at most auto parts stores. Everything else is still 'gasoline compatible' with no mention of alcohol.
    Tom
     

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