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Barrel Base Gasket?

Discussion in 'Norton Commando Motorcycles (Classic)' started by Brooking 850, Aug 7, 2018.

  1. Danno

    Danno

    Joined:
    Feb 7, 2010
    Last base gasket I used (1984) leaked, so I have been using the sealant-only method ever since with zero leaks.
     
  2. Deets55

    Deets55 VIP MEMBER

    Joined:
    Oct 3, 2013
    FWIW, Cometic makes a base gasket. Plug and play, leak free, and should be reusable. No worries about blocking the oil drain hole with sealing compound, and should release easily if de-construction is necessary. I used one on my primary, had it off twice for routine maintenance and still seals fine.
    Pete
     
  3. Hortons Norton

    Hortons Norton

    Joined:
    Oct 12, 2007
    Pete where can you find them?? I looked on their site and can't find them. Special order?
     
  4. Deets55

    Deets55 VIP MEMBER

    Joined:
    Oct 3, 2013
    You have to call them up. They have some stuff on file (computer) and will cut them special. I have been meaning to call them and see if they have the intake and exhaust valve cover gaskets on file. Give them some lead time, I think it took a week for the primary (MKIII) to come in.
    Pete
     
  5. Fullauto

    Fullauto VIP MEMBER

    Joined:
    Apr 13, 2009
    The only experience I've had with a base gasket on my 850 was a bad one. Oozed out.
     
  6. Ron L

    Ron L VIP MEMBER

    Joined:
    Feb 27, 2004
    Ultra Grey is an RTV silicone, that will cure in air and can get into the oiling system if you are not careful and use it sparingly. The Loctite 515, 518 products are anerobic and only cure in the absence of air, so stay liquid if squeezed out of a joint and will disperse in the oil. I have cleaned a number of cranks with little beads of silicone inside and separated cases with strings of silicone hanging from the inner surface. User beware.
     
  7. CanukNortonNut

    CanukNortonNut

    Joined:
    Aug 8, 2005
    The 4 Cap screws running through the barrels which can't be touched after the head gets dropped on, is part of the whole clamping system to the latter Commando evolution barrels. Using 518 as Ron L suggests will set once in absence of air. The Paper gaskets have a tendency to move around once the engine heat cycles and vibrates. A 750 prior to the through bolts, can be re-tighten. Not so easy with an 850 barrel.
    Cheers,
    Thomas
     
    concours likes this.
  8. concours

    concours VIP MEMBER

    Joined:
    Dec 29, 2011
    Just curious, as to why someone would want to use a gasket where the design was to not have one, reducing an already low 8.5:1 compression ratio even lower?
     
  9. htown16

    htown16 VIP MEMBER

    Joined:
    Apr 29, 2009
    Four bikes so far including an 850, all paper base gasket with 3bond on both sides, no leaks. Can't believe it would reduce the compression enough to notice. Have tried to remove gearbox covers and timing covers after using 3bond on both sides of a paper gasket. Had to beat holy hell out of them to get them loose.
     
  10. Danno

    Danno

    Joined:
    Feb 7, 2010
    It's the Threebond that's sealing your barrel, despite the gasket.
     
  11. Hortons Norton

    Hortons Norton

    Joined:
    Oct 12, 2007
    Called Cometic yesterday and ordered head, base, and both intake and exhaust cover gaskets. He said they didn’t have the timing cover gasket, which I found odd. I have their gaskets on my Buell and have no leaks so far. The shop that did the work on the heads and barrels highly recommended them. I have no idea how they will work on a Norton. Have any of you guys tried their head gaskets?
     
  12. baz

    baz VIP MEMBER

    Joined:
    May 26, 2010
    If you have a gasket fitted you really won't need any sealent just grease on the gasket
     
    blaisestation likes this.

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