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    Coil Issues?

    I recently picked up an 82 GS 650 and have been troubleshooting it. It would start but wouldn't run correctly. It lacked power. A lot of power. At first I thought it was a carb issue, bad diaphragms or something. After cleaning and inspecting them the problem still remains.

    I decided to check the ignition. To summarize, I don't have a spark on no. 3 or 4. But the funny thing is, both of the coils appear to be half bad. Each coil has one wire that appears to be alright and the other wire is dead. Also, I discovered that each and every spark plug on the bike is different.

    Any ideas on what is going on? I suspect both coils are bad but I want to be sure. Also, do you know any good sources for new coils?

    Thanks!

    #2
    Hi, you should be able to get some kind of Ohm reading from 2 small coil wires together and then spark plug wire to either of the small wires. If nothing else you can see if both the coils are similar. Check your manual for the coil Ohm rating.

    Comment


      #3
      Welcome.

      Coils don't go half bad, its all or nothing, so you have two working coils but possibly either bad wires or (more likely) bad plug caps.

      I would get fresh plug caps and plugs and try again.

      Good luck with it.

      Spyug

      Comment


        #4
        Running on two out of 4 cylinders could cause a lack of power

        Unscrew the plug caps and check those, and check the secondary impedance without the caps (copper core to copper core). When the caps go bad their resistance tends to shoot up - a lot. Stock caps are ~10k ohms. The normally recommended NGK replacements are ~5k. Trim back about 1/4" of the wire when re-installing caps to make sure you have fresh copper there.

        The secondary impedance is checked between the plug wires on each coil - not to the primary wires. Stock coils run ~12-15k ohms, stock wires are negligible (good thing because they're not normally removable), plus the boots. So ~33k would be "normal" with stock plug caps, or maybe 23k with NGKs.

        Buy all new plugs.

        Comment


          #5
          Wow, these 650's are everywhere! What model - E,L,G ? Has it been sitting a while waiting for you? Follow the link to Basscliff's site and be amazed at all the info, or wait till he welcomes you. How did you clean carbs? Put bike model/year in your signature to aid others when you post.
          1981 gs650L

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

          Comment


            #6
            Greetings and Salutations!!

            Hi Mr. rklobster,

            Here is your magic formula for getting your bike in good order. See the maintenance lists in your "mega-welcome". Every task is critical. Any shortcuts will leave you frustrated at best, and dead at worst.

            Anyway, let me dump a TON of information on you and share some GS lovin'.

            I just stopped by to welcome you to the forum in my own, special way.

            If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

            Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. This is what NOT to do: Top 10 Newbie Mistakes. Now let me roll out the welcome mat for you...



            Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

            Thanks for joining us. Keep us informed. I will put you on my prayer list.

            Thank you for your indulgence,

            BassCliff

            Comment


              #7
              The first thing I would do is:
              Remove each cap (do all 4)
              Cut about 1/2" - 3/4" from the tip of the spark plug wire. These tend to get worn, corroded, etc. over the years
              Look at the copper wire strands in the center of the spark plug wire
              If they are bright and shiny copper, reinstall the caps and test again
              If they still look a bit black (oxidized) trim those wires in increments of 1/8" until shiny
              That gives you the very best of the coil output to the tips, after that it is the caps themselves.
              And it costs no money and takes little time.

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