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Spark plug leaks

Discussion in 'The Garage' started by David Toll, Jul 31, 2020.

  1. David Toll

    David Toll Reliving my youth? Top Contributor

    OK Max, consensus is that your powder trick works. My apologies if I inferred otherwise, I'll try it. Thanks for your suggestions friends, I'll consider them all over the next few days. I take it that no-one is recommending that I do a rethread at the moment.
    Cheers
     
    Boog and Jim like this.
  2. Machine

    Machine Race the wind Top Contributor

    I'll share that my right side 78E spark plug hole has a bit more "wobble" than other XS's I've owned. It is machined with less perfection. The thread "minor" has flats on one side. This also concerns me and just being aware and perhaps more careful or light handed on the spark plug torque value has resulted in no failure so far. To rethread a spark plug hole, which is cast aluminum, seems to me to require removing the head. Or maybe being very careful it could be done? Timesert is much stronger than Helicoil as it is a solid one piece insert.
    You can carefully chase the existing holes with a tool such as shown here. I would recommend using anti seize as a lube/ cutting agent.
    20200801_101046.jpg
    I'll also share to find and have a spare head to rebuild and have as back up is a good idea..-R
     

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  3. Jim

    Jim Beyond the edge, is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    The combustion chamber, including the plug hole... is steel. The aluminum "head" is cast around those two steel domes.

    IMG_20200801_205431.jpg
     
  4. Machine

    Machine Race the wind Top Contributor

    20200801_190847.jpg
    Check into it again as I am now as well. I am checking with a magnet as well as magnification. It looks and acts to me that the steel dome surrounds the threaded holes but the holes really seem to be aluminum. Which is why I have been concerned as David is. 20200801_190948.jpg
     
    Boog, grizld1, Paul Sutton and 2 others like this.
  5. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    Kinda what I thought too. I've gotten an XS motor or two with stripped plug holes.
     
    Boog, Paul Sutton, Jim and 1 other person like this.
  6. Jim

    Jim Beyond the edge, is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Just checked with a magnet. I stand corrected. The threads end where the steel dome begins.
     
  7. Machine

    Machine Race the wind Top Contributor

    Good for all to know :)
    I say "the day you quit learning, is the day you're dead"
    -R
     
    lakeview, Boog, grizld1 and 5 others like this.
  8. Jim

    Jim Beyond the edge, is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Fwiw, I've done plug helicoils in situ on Lycoming engines. We'd turn the prop until the exhaust valve is open. Spray in a ton of fast drying solvent if it looked oily inside, blow it dry with shop air, then re-cut the threads. Take a blowgun again and blast in the hole 'till your arms got tired. More solvent and air blasting... Red loctite the helicoil in and done. It's doable.

    But just to repeat David.... your problem lies elsewhere. ;)
     
    Boog, grizld1, gggGary and 1 other person like this.
  9. David Toll

    David Toll Reliving my youth? Top Contributor

    Yes, I've read where you bring the piston to TDC, stuff the cylinder chamber with a grease soaked rag and coat the cutters with high temp bearing grease to pick up the metal bits. The cylinder is wiped out with a metho soaked cloth and vacuumed or blown if you have a compressor. I'm undecided on the rethread bit but I will try Max's powder test before I do anything silly.
    Unfortunately, I have to run the bike to get a leak and my starter has decided to give up the ghost - shame 'cause it was working beautifully. She kicks OK but, with my missing toes, I prefer the "electric" approach so the starter takes priority. The old girl is playing hard to get but she's met her match!
    I'll sneak a question or two in here, rather than start a new thread.
    Should this mounting terminal on the starter turn as I tighten the first nut? This one rotates and as it turns, it affects the starter action. What is this terminal attached to inside the starter body? Didn't strip her down when I had the motor out but hey! I was young and foolish then. Might get the chance to practice now...... dammit!
     

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    Jim, Boog, grizld1 and 2 others like this.
  10. Max Midnight

    Max Midnight XS650 Addict

    Provided you can torque the plug to spec and the land on which the sealing washer sits is flat then I doubt that the threads are an issue.
    However, it would be possible to check for leaks by putting a soap solution around the plug and turn the motor over. Any leak will cause the solution to bubble. You may need to create a 'dam' of plasticine or Blur Tac around the plug to contain the mixture,

    If that doesn't produce a result at least you will have something to wash off all of the powder! :D
     
    Jim, bikefreakjon, Boog and 5 others like this.
  11. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    Yeah if that post spins you're going to be going into the starter motor, such an easy, enjoyable little project. :confused:
     
    David Toll, GLJ, Jim and 2 others like this.
  12. grizld1

    grizld1 Grumpy old man Top Contributor

    Oh yeah, opening the starter is much fun. But while you're in there you can clean up the commutator; you might be surprised at the difference that makes.
     
  13. joebgd

    joebgd XS650 Addict

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    I would try adding or changing the spark plug wahser to see if that gets it a little more sturdy for ya.
    I don't have info on the starter but I'm going to be on that to soon starting w tightening the #4 gear spring.
     
    David Toll and Jim like this.
  14. 2XSive

    2XSive At least one screw loose behind the handle bars XS650.com Supporter Top Contributor

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    FWIW, I've installed helicoil sparkplug inserts without removing the head. Put cylinder at top dead center. Use grease liberally on the tap to catch as many shavings as possible, only make a 1/8th - 1/4 turn at a time, back it out, clean it up, reapply grease, and repeat. Take your time and you won't get any shavings in the cylinder. Use a shop vac continuously between cuts. When done, compressed air any loose remaining shavings out of the cylinder, use an inspection camera to inspect cylinder to verify clean. Ran my XS for many miles afterward until I learned camchain guide was toast. After topend rebuild that original helicoil repair is still working great (stronger than original aluminum threads).
     
    David Toll, Machine, grizld1 and 3 others like this.
  15. bikefreakjon

    bikefreakjon XS650 Addict

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    What max said, spray soap at the plug and look for bubbles.

    You damaged the connection to the brush in the starter when the post started spinning.

    Taking a step back, there is no oil to leak behind the plug so it's coming from somewhere else. As my boss says, "it's leaking? Find the leak then!"
     
  16. David Toll

    David Toll Reliving my youth? Top Contributor

    I'll do the soapy water test. I have read that the staining around the plug could be "soot" from the combustion chamber - more likely than the impossible "oil" I've been imagining. Member Prue 1 brought up the topic in 2014. Fred and RG gave some opinions on its source.

    The response here has been, as usual, excellent thank you gentlemen. As I indicated in post #29, the starter has become my primary concern and, as the plug issue requires the use of untried and possibly inadequate skills, I will hold off that project for the moment until I've checked all alternatives.

    Time to remove the starter eh? You know, I looked at the bloody thing a half-dozen times when I had the motor out and considered stripping it down - would have been a damn site easier. Obviously, lack of confidence and impatience don't motivate common sense.
    Some research, purchase of seals and maybe 4th gear assembly and take it off. I know INXS posted some good info on the starter system back in 2010. Do I detect a note of sarcasm in your responses, Gary and Griz??
     
    Last edited: Aug 2, 2020 at 7:40 PM
  17. bikefreakjon

    bikefreakjon XS650 Addict

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  18. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    And a double jointed little girl....
     
  19. David Toll

    David Toll Reliving my youth? Top Contributor

    Just discovered a thread from 2013 by YL82 where he explores the possibility of replacing the terminal stud. Appears to be unserviceable - the inner end of the stud "is silver-soldered to the field windings in the motor case", according to Downeaster. Looks like a new starter. I'll dismantle and take a look, but not 'til I get the seals - I can still kick her.
     
    Boog, gggGary and Paul Sutton like this.
  20. stinky78

    stinky78 XS650 Enthusiast

    hi David, does it smell like fuel or oil? if it really is oil I’d have to agree with Jim, you’ve got other problems, I take it that you’ve tried a new plug in it? in case it’s the sealing washer.
     

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