Best way to repair spark plug threads in place?

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  • LarryJ
    • Jan 2026

    #1

    Best way to repair spark plug threads in place?

    Well, while doing a compression test on Miss"Suzi"Terry('82 1100GK), I cross threaded going into #2 plug.

    It's fudged!

    So, what is the best was to repair it in-place? Helicoil? Timesert?

    Well, at least compression is good on all cylinders@135-145psi.

    Just wish that compression tested had threads that weren't so sharp!

    It's a real pain when you screw something up that you should have known better!
  • Guest

    #2
    I did that on my 850 once, managed to rethread it with spark plug hole threader. Coated it with oil/grease, can't remember which. Just went forward a small amount then backed it out and cleaned off the metal, then threaded it back in a bit more with new grease on it. Worked great. After that the spark plug would start to thread in a little loose but once you got down more it would tighten right up. Just always had to keep in mind to be extra careful taking out and putting in that specific plug.

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    • LarryJ

      #3
      Cool ! Thanks for the supportive suggestion.

      Comment

      • Johno
        Forum Mentor
        • Aug 2007
        • 474
        • Sydney Australia

        #4
        Try a plug chaser

        You may not need an insert just a chaser to clean up the thread.

        http://www.tridon.com.au/Products/Pr...&G=599&P=64356

        I have used a chaser on my bike with great success when I thought I had stripped the thread.
        Johno

        current rides 1981 GS1000G and 2005 GSX1400
        1977 Kawasaki KZ400 D4

        previous bikes 1978 GS1000HC
        1977 GS400
        1974 Montesa 250
        1960s Kawasaki 175

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        • tom203
          Forum Guru
          Past Site Supporter
          • Aug 2010
          • 8925
          • Norway,Maine

          #5
          Originally posted by Johno
          You may not need an insert just a chaser to clean up the thread.

          http://www.tridon.com.au/Products/Pr...&G=599&P=64356

          I have used a chaser on my bike with great success when I thought I had stripped the thread.
          Yes indeed, just put some thick grease on chaser so any chips stick to it.
          1981 gs650L

          "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

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          • Guest

            #6
            You tightened it all the way down? If you just started it a tap will clean things up with grease to catch the shavings.

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            • LarryJ

              #7
              The thread chaser tap worked!
              Cleaned up the threads today with a chaser tap.
              The spark plug is in straight & tight!

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              • Guest

                #8
                Fantastic, talk about an 'oh crap' moment turning to a 'dynoooomight' one. Good news.

                Comment

                • Johno
                  Forum Mentor
                  • Aug 2007
                  • 474
                  • Sydney Australia

                  #9
                  Originally posted by LarryJ
                  The thread chaser tap worked!
                  Cleaned up the threads today with a chaser tap.
                  The spark plug is in straight & tight!
                  Good news!!!! I've experienced the ups and downs with cross threading a plug. it is a great feeling when you get things cleaned up and seating properly again.
                  Johno

                  current rides 1981 GS1000G and 2005 GSX1400
                  1977 Kawasaki KZ400 D4

                  previous bikes 1978 GS1000HC
                  1977 GS400
                  1974 Montesa 250
                  1960s Kawasaki 175

                  Comment

                  • LarryJ

                    #10
                    Now, I am tackling the broken cam cover bolt. I need to get a tap & the correct drill bit for it. I already have the bolt cut off at the head & a pilot hole started. Now , I have to finish it & get a new cam cover. Had two bolts rusted solid into the cam cover. Worked one out. The other one broke at the head.

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                    • spaytons

                      #11
                      You ever try 'easy outs'? They're like reversed drill bills. I use them here at work and used them on some trucks I've owned. Might save the drilling and tapping. I think you can get a set for less than 10.
                      Last edited by Guest; 06-25-2012, 01:20 PM.

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                      • razor02097

                        #12
                        Yes many have tried easy outs....and many will never try them again.

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                        • RobG1970

                          #13
                          Originally posted by spaytons
                          You ever try 'easy outs'? They're like reversed drill bills. I use them here at work and used them on some trucks I've owned. Might save the drilling and tapping. I think you can get a set for less than 10.
                          Don’t use a easy out on this project, just drill out the broken screw. The aluminum fused with steal screw and now are ONE. The easy out will just break off inside and then you have to take a dremel and dig it out.. I suggest getting a left hand drill bit one size smaller then the treads, drill down the center of the broken bolt and then re-tap it with the correct 6mm tap. How I know this, is I did the above the hard way, and while digging out the bolt went through the side of the head and had to pay a welder to come in and fill the hole with aluminum at 80 bucks a hour.. BTW it took him longer to set up the welder than to weld it.. so about 10min total for 80 bucks… NOT A GOOD TIME WAS HAD... you can get the left hand drill bit at mendars, and Ace Hardward sells the new bolt.
                          Good Luck,

                          Rob
                          Last edited by Guest; 06-26-2012, 09:48 AM.

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                          • spaytons

                            #14
                            Originally posted by RobG1970
                            The aluminum fused with steal screw and now are ONE.
                            Eck! Good point. Ignore my suggestion.

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                            • LarryJ

                              #15
                              Now,I just need to find a reasonable & instock local place forp the tap & the tap drill bit .

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