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Lesson Learned

Thursday, October 2, 2008




Yesterday at Kroger’s Market, I ran into Tom, an 83-years-young who rode a Yamaha Vino 50 and could be seen all over town in Beaumont, who told me that he could use some assistance with his scooter.  Notice the underlined “rode”.  Well, until recently, yes, he rode; but Tom made a costly move when replacing a spark plug, he used a socket wrench instead of first threading the plug in with his hand.  What happened next we will never know; but judging from the result, a broken spark plug, one is led to speculate that he might have crossed the threads as he turned the socket wrench.  The plug, whose threads might have been slightly misaligned from the start, turning deeper and deeper into the soft aluminum head, creating a new thread pattern until it could no longer be turned anymore and broke off…


Whats missing in this picture?

What's missing in this picture?

Two possible repair options here: use an Easyout to extract the broken sleeve (but be aware of metal shavings falling into the engine); or pull the head off and try getting it from the other side (which maybe a better way; but could get more involved).

The threaded (sleeve) portion of the spark plug remains in the hole

The threaded portion (sleeve) of the spark plug remains in the hole

Lesson learned from Tom’s experience:  Always thread the spark plug in with hand first, and make sure that it screws in smoothly with very little effort.  Any sign of difficulty should be taken seriously.  Stop! Back it out and never use a socket wrench to force it in.  Continue screwing the plug in until it stops, and then carefully apply the socket wrench, or a torque wrench until the proper torque setting is achieved (see your manual for spec); but never overtighten the plug.  As an added precaution, apply small amount of anti-seize to the threads on the plug before replacement as this would help with trouble-free removal in the future.

Has this ever happened to anyone out there?  I would like to know how you solved the problem.–Lorenzo

5 Comments leave one →
  1. Sunday, October 5, 2008 11:47 am

    I used to have a 73 VW. I got one of the plugs cross threaded. It didn’t want to back out, so I just left it. I drove it for about 8 years with that plug (Bosch). It was still running fine when I sold it earlier this year. Wish VW made a scooter.
    I have a picture of it on my MySpace.

  2. Sunday, October 5, 2008 3:22 pm

    Wow, that’s amazing, Denny! Good thing you didn’t try to muscle it out.
    Glad that you could ride with us yesterday, and Happy Birthday!–Lorenzo

  3. Sunday, October 5, 2008 7:46 pm

    Try an ease out, while holding a good shopvac close to the hole. If it’s a four-stroke, turn the crank till the exhaust valve is open to allow the air to flow back out of the cylinder. You could also attach an air hose to the exhaust to cause pressure in the cylinder (exhaust valve open). That way any particles would blow back out the spark plug hole. May have to install a hellicoil to repair the threads in the spark plug hole.

  4. Sunday, October 5, 2008 10:34 pm

    When I break things, or blow things up, I can usually justify a performance upgrade. Tom is most likely wiser but I’d have to throw a kit on it.

  5. Sunday, October 5, 2008 11:00 pm

    Hey, Paul

    I know you would (throw a kit on it)! But first, Tom will have to get that sleeve out.

    I’m also thinking about making it to “Who Day”. Maybe I can get a few more riders to join me. Ed’s Scarabeo is on the blink; but I still hope that he can make it. Wanna help us plan a nice route to DeRidder, Paul?


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