GSX-R 750 Pictures of how I replaced the coils on my 1985 1986 1987 Suzuki GSX-R750 motorcycle.

But first, lets pay some bills:

  1. My beautiful 1986 GSX-R750 was only firing on two cylinders at idle. This is bad. I swear I tested the plugs and all four were firing. But if I removed the spark plug wires for cylinders one or four from the plug at idle, it had no effect on how it ran. So those two are not firing. Both one and four spark plugs are fired from one ignition coil. So I'll go get my tools.

  2. There are the coils. The two grey boxes with the spark plug wires coming down out of them.

  3. I ran a resistance test on the primary, low voltage side of the coil. My FSM says that should be between three and five ohms. I get 4.1, so that is dead on.
    primary test

  4. The secondary side of the coil did not test quite as well. I was looking for 25-45,000 ohms. Whatever it should be, it definitely should not be OF, Open Fault.
    Open Fault

  5. But wait. Maybe the fault is in one of the end pieces that attach to the plug, and the coil is fine. To test this cockamamie theory I took off the end pieces and tested again.

  6. They just unscrew off the wires.

  7. Failed that test too. OF.

  8. Maybe it's the wires that are bad. I'm just trying to avoid buying new coils. A clip on the body of the coil holds the wires in.
    clip     clip

  9. Small screwdrivers and some careful application of force got all the clips on the clip unclipped.

  10. Off comes the clip. The clip is pretty brittle and old. I broke one of them on, spoler alert, the new coil I had to buy.

  11. Nope. Basically no resistance in the wire. Wires are fine.

  12. A lot of resistance in the wire end piece, though. Hmmm. This is fine, and was designed to be that way. But I don't cotton to it. See the Spark link in the menu on the left.

  13. So, I got a new coil and it runs fine now. Yay.

  14. Next I sold out to make 02ยข so I can fulfill my lifelong dream of owning a 1986 944 with blown head gaskets.

    But no minivans!

  15. Then I finished my beer.

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Disclaimer: The technical information in these documents is provided without any warranty whatsoever and at no cost.   All information is in general terms and is not meant to apply to your particular situation, be current at the time you read it, or even be correct in the first place.   Improperly maintained vehicles can lead to serious injury, death, or unavoidable accidents. The author is not responsible for any errors on this site, and does not make any claim at all about the validity, safety, or veracity of the information contained on this website. Any work you choose to do or not to do on your vehicle is done at your own risk. The information on this site is not intended to serve as a replacement for professional advice, professional workmanship, dealer service, union labor, or psychological counseling.   The author disclaims any and all liability directly or indirectly arising from the application or use of any information or idea contained on this or any other web site.   By opening this page, you agree to never sue anyone ever or allow anyone to be sued on your behalf.   The appropriate professional should be consulted regarding your specific condition. does not take responsibility for the information posted on other sites to which it links.

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