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well blackened spark plugs

Discussion in 'Norton Commando Motorcycles (Classic)' started by seattle##gs, Jul 10, 2019.

  1. seattle##gs

    seattle##gs

    Joined:
    Oct 28, 2014
    I removed a pair of spark plugs which were twin balls of soot but the unusual thing is that they are blackened halfway up the threads. Any ideas?
    Way too rich of course. The head had loosened and been ridden
     
  2. comnoz

    comnoz VIP MEMBER

    Joined:
    Dec 10, 2008
    It sounds like the threads in the head may be getting worn out.
     
  3. Steves

    Steves

    Joined:
    Oct 16, 2016
    I might try some copper paste and nip them up after cleaning. Helicoils are the normal fix I think. Running rich change out the .106 needle jets for new (assuming your current not new) as first step. While carbs are off give them the once over obviously, though you can change jets in situ. Also check air filter. Hours of fun ;)
     
  4. MichaelB

    MichaelB VIP MEMBER

    Joined:
    Jan 14, 2004
    What kind ignition, plugs and plug wires are you using?
    Weak ignition with 5k plugs and 5k plug caps will compound poor carburation.

    The threads are another issue.
     
  5. seattle##gs

    seattle##gs

    Joined:
    Oct 28, 2014
    solid core wire and no resistor caps. resistor plugs. Boyer.
    It is just curious that the carbon could go so far up the plug threads
     
    MichaelB likes this.
  6. Torontonian

    Torontonian

    Joined:
    Dec 28, 2009
    Never seen carbon wick up into the threads like you describe. Likely the aluminum threads are pooched ? If you plan to pull the head in the near future you could think about threading in a new plug from the inside vs. normal outside and feeling if it goes in sloppy for the first half of inserting. That would explain it and you could take the head into the shop for new thread inserts. Just an idea.
     
    Craig likes this.
  7. seattle##gs

    seattle##gs

    Joined:
    Oct 28, 2014
    The motor was freshly built a while back, few miles on it. It belongs to someone else and I really don't want to take the head off
     
  8. Danno

    Danno

    Joined:
    Feb 7, 2010
    <----That blew a plug out riding around Daytona a couple of years ago (when the pic was taken), but apparently nothing wrong with the threads, Must have shook loose, is all I can think. I got the plug wrench out of the tool kit, along with a pliers to reinsert the hot plug and screwed it back in. When I get around to pulling the head for a new head gasket, I'll check by threading a plug in from underneath.

    I still have a small box of helicoils I used to put in Britbikes with knackered plug threads, but never had to use one in my own. If the need were to arise, I'd avoid using them and instead employ a Time-Sert or something similar. Much more secure than a glorified spring.
     
  9. Torontonian

    Torontonian

    Joined:
    Dec 28, 2009
    Yes I hear Time-Sert is the new way , not helicoils.
     
  10. Dommie Nator

    Dommie Nator VIP MEMBER

    Joined:
    Apr 2, 2013
    I'm hoping not to pirate the thread too much but it may also become relevant to the original post.
    I have a question about Time- Serts.
    I put a couple in my head and I was advised ( I can't remember by whom ) to run a slightly cooler plug because the heat transfer from the plug through the steel insert isn't the same.
    I have asked this question before on here but the thread sort of died before an answer.

    What would be the advice from the trusted few on here?
     
  11. Craig

    Craig VIP MEMBER

    Joined:
    Dec 20, 2005
    Only place I have ever used a timeSert is on Commando sump drain plug , bought the kit followed instructions , no worries just worked perfect , last drip fixed ... only down side was I paid for 5 timeSerts and used 1 .... no doubt the TS would work better than Helicoil in spark plug threads , no opinion on the heat question , sorry
     
  12. Danno

    Danno

    Joined:
    Feb 7, 2010
    I think if you used some copper anti-seize on the Time-Sert and the plug thread, you'd have no heat transfer issues.
     
  13. htown16

    htown16

    Joined:
    Apr 29, 2009
    I've got a timesert in my 72's head. I run NGK 8's on both sides. If anything the other side runs a bit hotter.
     
  14. Danno

    Danno

    Joined:
    Feb 7, 2010
    To me, that indicates the Time-Sert may facilitate heat transfer rather than stymie it. It's worth a plug-range experiment not to have to worry about a crappy helicoil coming out with the plug upon removal. Or worse, sticking down into the combustion chamber and possibly breaking off.
     

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