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phenolic sealer

Discussion in 'Norton Commando Motorcycles (Classic)' started by seattle##gs, Aug 15, 2016.

  1. seattle##gs

    seattle##gs

    Joined:
    Oct 28, 2014
    I have suspicions about the sealing ability of the phenolic spacer used in the intake system. I tried using yamabond and a week later there was not a trace. I can only conclude that it got sucked through the motor which means that air is currently passing through on both sides of the spacer. The same phenolic spacer on my BMW /2 has a paper gasket bonded to each side and I would like to see it available for Norton. Is there any sealer that would stick to the phenolic? Yamabond isn't it.
     
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  2. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    I use Wellseal, but if the joint surfaces aren't flat then you could use a thin paper gasket each side.
     
  3. dynodave

    dynodave

    Joined:
    May 28, 2003
    NHT in featherbeds have a solid 1"thick manifold and air leakage doesn't appear to be an issue. Commando 68-70 "early" curved small fin manifold were IMO a defective design and the inlet flanges easily warped. This was especially noticeable on Dunstall style tuned early manifolds that were "ported" for 32mm carbs for "ported" 32mm precombat heads. Norton corrected the design for 71 + with a more rigid flange for all 3 sizes. I have never had problems with late manifolds and the thick or thin phenolic insulators that actually caused a fuel mixture problem.

    I've had way more problems with stripped or cross threaded or raised threads at the head.
     
  4. Danno

    Danno

    Joined:
    Feb 7, 2010
    I use Permatex Spray-On Copper Coat for an even surface. Works on paper gaskets, too. Other sealers may work, but they're not as easy to get an even coat without adding thickness to the assembly.

    One thing I've noticed on paper gaskets, especially gearbox and primary chaincase gaskets is, over time, the acid in the lubricants tend to get soaked up and turn the paper into mush causing leakage where there was none previously. The Copper Coat should help preserve those gaskets longer.
     
  5. maylar

    maylar

    Joined:
    May 13, 2007
    Permatex High Tack works for me. Though I have used plain old clear RTV and never had any leaks.
     
  6. concours

    concours VIP MEMBER

    Joined:
    Dec 29, 2011

    I use thin paper gaskets on each side of phenolic. Highly not recommended here by many, but 27,000 miles of good service, no troubles tells me it's not so bad. I too, couldn't accept the idea of phenolic to seal.
     
  7. gtiller

    gtiller VIP MEMBER

    Joined:
    Nov 5, 2012
    +1 on paper gaskets - I paint them with Wellseal then hang them up for a few days until they go nice and tacky.

    Works a treat!
     
  8. eskasteve

    eskasteve VIP MEMBER

    Joined:
    Sep 24, 2012
    Hylomar sealant has never let me down. It seems to seal when nothing else works. Plus, unlike some sealing compounds, it's gas proof. It's a sealing product that from what I was told was developed by Rolls Royce back in the early '60s. I had a stubborn leak on the rocker spindle cover bolts and tried everything. An old BMW airhead mechanic told me to try Hylomar and it solved the problem.
    I usually pick up a tube whenever I'm in Everett at Pep Boys . Toyota has a branded version of Hylomar if you can't find it nearby.
     
  9. auldblue

    auldblue VIP MEMBER

    Joined:
    Nov 20, 2012
    What thickness should the spacers be.? I have thick ones on but the new ones are half the thickness.

    Jg
     
  10. Danno

    Danno

    Joined:
    Feb 7, 2010

    All of the -bond products such as Yamabond, Kawasakibond, Toyotabond(?) and Permatex Moto-Seal are basically the same thing as Hylomar.
     
  11. seattle##gs

    seattle##gs

    Joined:
    Oct 28, 2014
    OK...I've ordered a tube of Hylomar because everybody recommends it and I'll go with the paper gaskets. I have used Yamabond since the mid seventies with excellent results....

    After 40 years I finally made a special Allen wrench to reach the near impossible allen bolts holding on the carbs and manifolds...a few minutes with a hacksaw and a welder and a BALL END allen and now I no longer dread the job of carb removal.

    I remember in the early '80s with my first Commando, a '75 MK3, and living in Yerington Nevada...nothing but long straight roads and 100 miles from any other town. I had installed the carbs and manifolds and for some reason the plugs were running white. So I richened...and richened...and richened...this was ideal for testing with no traffic and sustained 70 MPH for as long as I wanted. The plugs would not darken but I kept picking up better performance and still had a good idle. This was a real mystery and one of the very few that has ever been in my favor. What I finally discovered was that the phenolic spacers had been leaking air GRADUALLY as more and more of the yamabond was stripping off and disappearing down the Norton's gullet. I was simply richening to keep up with it. I am willing to guess that this is also other people's problem as they try to dial in their Amals. I didn't catch it for a long time because both carbs were doing it equally and I would not let myself believe that Norton could allow this easily solved problem to reach the public.

    Another thing about Yerington...Their main crop is Hay and they have huge fields of it...and lots of irrigation. So as I was zipping down the back road at 70 or 80 (younger days) testing carburetion I noticed that the bike would gain power as I ran alongside the hay fields and lose power when they ended into long strips of desert. I think it was around 3500 or 4000 feet in altitude.
     
  12. RoadScholar

    RoadScholar VIP MEMBER

    Joined:
    Dec 28, 2008
    Hay growing? Produces oxygen?
     
  13. seattle##gs

    seattle##gs

    Joined:
    Oct 28, 2014
    the fields are being irrigated by large sprayers...the air by the field is a little colder and more dense.
     
  14. chaztuna

    chaztuna VIP MEMBER

    Joined:
    May 5, 2017
    Danno,
    Actually, that is not correct. See the thread linked below. I mention this, so that future readers of this thread are not misled. See

    https://www.accessnorton.com/NortonCommando/crankcase-sealer.24648/#post-364124

    I find it interesting that there are reports of Yamabond, etc dissolving [over time] when used on the intake system. They all have silicone as a minority constituent of their composition. I know that you should never use RTV silicone sealants on the fuel system. Gasoline [aka petrol] will dissolve RTV. I've used gasoline to clean RTV off of engine parts in the past. There are a number of reports in the NTSB [National Transportation Safety Board] archives regarding this. Instances where aircraft mechanics applied RTV to the float bowl gaskets of Marvel - Schebler [Lycoming & Continental piston engines] carburetors. Over time, the fuel dissolved the RTV, which then became lodged in either the float needle/seat or the main jet. This caused engine failure and either a crash or emergency "off airport" landing.
    Like the OP, I never trusted the phenolic insulators to create an air tight seal. I always installed paper gaskets or Hylomar Universal Blue, with good results. Do most of you use some sort of sealant at this junction? Or is air leakage here simply not an issue?
     
    Last edited: Mar 14, 2018
  15. chaztuna

    chaztuna VIP MEMBER

    Joined:
    May 5, 2017
    Dave,
    Do you simply assemble as shown in the exploded view? Or do you apply a sealant?

    That does not surprise me. A "ball end" Allen key and patience go a long way here.
     
  16. NortonMKIIA850

    NortonMKIIA850

    Joined:
    Jul 20, 2017
    I just make sure the surfaces are clean, no gaskets or sealant, seems to work fine for me.
     
  17. hobot

    hobot

    Joined:
    Oct 19, 2005
    Because its bad juju to clamp Amal flimsy flanges very much over the factory oil ring or to get to seal on flat gaskets and goops vulnerable to fuel blasts and heat insulation matters, I cut rubbery sheet gaskets as well as 'thick' hard wood spacer.

    Note: one of Ms Peel's surprise power adders occurred when just wanted expedient carb install so crudely cut a rubbery/fiber embedded gasket that slightly intruded 1/6" into air flow with very rough/sawtooth edges. Enough so never cleaned it up - against all respected wisdom advice here. If bored easy enough to do to see if noticed good or bad.
    https://www.google.com/search?clien....1.64.psy-ab..3.11.993...0i67k1.0.IzC5iZXN3yM

    https://www.google.com/search?q=wood+carb+spacers&ie=utf-8&oe=utf-8&client=firefox-b-1

    https://www.google.com/url?sa=t&rct...ms_72153.pdf&usg=AOvVaw32p_Wlu1fd9b1oZK2BcD7Z
     
    NortonMKIIA850 likes this.
  18. dynodave

    dynodave

    Joined:
    May 28, 2003
    I assemble a (good original smooth) phonelic spacer-manifold-carb using the standard original type hardware and never had a problem. rough spacers, probably crappy aftermarket, seem to be the ones people have to doctor up with goo. Over the years I have made some but I'm very particular about the material.
    Early thin flange manifold are problematic, how do you fix/flatten them when they are already too thin? It would seem over tightening is what kills them.
     
  19. Danno

    Danno

    Joined:
    Feb 7, 2010
  20. texasSlick

    texasSlick VIP MEMBER

    Joined:
    Jan 2, 2013
    +1 regarding my Atlas manifolds. I have used my original phenolic spacers until just recently, and have replaced with new AN. I suspect problem is more related to warped manifolds and home made spacers than poor sealing qualities of phenolic.

    Slick
     

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