1980 gs850 coil electronics confussion

[Guest]

Hello I am certain this has been asked in the past, but unfortunately I was unable to find any info. I have a 1980 GS850, new to me... It has Nov. of 1980 as its manufacture date. My left side coil resistance is measuring below the specified amount. I need a new coil. I look at the parts diagram for the year and model of my bike and get the part number 33410-45112, when I look up the coil, it says it is for a points system. My bike has the CDI (full-transistorized ignition system). Apparently, the early 80 models were point systems and then a change over during the year, or a difference in the model of that same year. The service manual shows a points system for some models and the transistorized ignition for others. Point blank, I am at a lose for which coil my bike is supposed to have. Both coils had readings of 4.2 ohms on primary side, left one had 22k and right one had 32k on secondary side. Has anyone had any trouble this way with this model year? Can someone recommend the proper ohm readings of the coil my bike should have?

Also, I was wanting to test my ignitor, the manual calls for an x1Ω meter range with the ignition on to perform this test. This is an ohm range and I concerns about testing charged wiring while my meter is set in this range, I don't want to ruin my meter..lol. Is this correct or am I misunderstanding the range setting I am supposed to use? Thanks

[tom203]

You should have electronic ignition (with an ignitor, not CDI), so take off little cover ( lower right side in front of brake petal) and convince yourself. You'll probably see two small signal coils.

When checking ignition coils, best to unscrew spark plug caps and stick meter probes into wires going to coils- secondary should measure about 12 kohms wire to wire. Plug caps are trickier to measure due to corrosion, might be 5k to 10kohms depending on brand.

Just what problem are you having? Have you been to Basscliff's site and seen this testing?

http://members.dslextreme.com/users/storagecliff/images/electrical_odd-n-ends.html#A17

[Damack]

Tom thank you for your reply, you are right it is an electronic ignition. Also, I did jump the gun on the bad coil, I did not perform all the test, that that page you supplied shows. Real quick, I truly love this bike, I am older and had one years ago and do not like the ride set up of the newer bikes, call me old fashions..lol.

I purchased this bike for $100, thus far I have, thoroughly cleaned the tank installed new pet cock. Thoroughly cleaned and rebuilt carb, stock jets, all new floats, floats seat, complete dunk and rubber. Checked valves, which were in spec. New intake boots. and off course new battery. a few other misc here and there. The problem I am having that leads me believe I have a coil problems is my 1 & 4 are carboned bad and 2 & 3 look very good. I was wanting to finish up my carb sync but just couldn't get her to run steady enough to do so. I have put new spark plug covers on, which led me to believe "coil" issue. I will follow the procedures offered by mister matchless to truly find my problem. One last thing is that during a simple test none of the plugs seemed to have a strong blue spark, but again 2 & 3 looked good after running and examining. Again thanks for your response and help...

[Nessism]

November '80 build date means the bike is a 1981 model.

All GS's, including the 850, received an electronic ignition system for the 1980 model year. This was not a running change, the switch-over occurred at the start of the model year.

As tom suggests, this system uses an ignitor, not a CDI, which is a completely different type of ignition system.

The GS ignition coils are quite reliable. The plug wires and spark plug caps are the weak link. Most common issue with coils though is voltage supply from the harness. There should be at least 11 volts. Some people add a relay to the system to make sure the coils receive full battery voltage, others clean the harness connections instead.

In summary:
Check voltage at coils and do what's necessary to get 11 volts minimum
Check spark plug cap resistance
Cut back the plug wires 1/2" or so and rethread the cap back onto the wire. The wires themselves can be replaced if necessary. Lots of threads on how to do so in the archives.

Good luck

[rustybronco]

My left side coil resistance is measuring below the specified amount. I need a new coil.

Both coils had readings of 4.2 ohms on primary side, left one had 22k and right one had 32k on secondary side. Has anyone had any trouble this way with this model year? Can someone recommend the proper ohm readings of the coil my bike should have?

In summary:
Check voltage at coils and do what's necessary to get 11 volts minimum
Check spark plug cap resistance
Cut back the plug wires 1/2" or so and rethread the cap back onto the wire. The wires themselves can be replaced if necessary. Lots of threads on how to do so in the archives.

Good luck

As Ed has already stated, check the resistance of each spark plug end cap. I think you will find your answer there.

[tom203]

Yes, try cutting back plug wires a bit or just get new plug caps -less than $5 each. When you get this thing to run, check charging system asap- do a quick test in this link -

http://www.thegsresources.com/_forum/showthread.php?p=1272192#post1272192

[Damack]

Thank for the replies. I did pull the covers off and did receive consistent reading of 12 or so from both coils, also did the check of the signal generator and received a 332 reading, which was on the mark with the spec for it. Because the covers are band new NGK, from z1 with a rating of 5k on the resistance, I thought I might have failed at proper installation. I re installed them and started her up. The bike ran very good for about 5 min, it was so smooth I could feel it very intermittently miss every once in awhile. I chalk up the miss to carb as I have been pulling the fuel in and out every time I shop test it (or attempt to shop test it) and haven't had the chance to adjust and sync it. After shutting it off and getting my sync tool and a few other things, I tried to restart it, it was still somewhat warmed up from having just ran. Unfortunately, she would not fire, so I did a quick spark test only to discover I had weak spark on the number 2 cylinder and no spark on 1,3,4. Here I go again...lol. I am now thinking that the time it sat without use, might have also damaged the wires. So I put it away for the day, with the intentions of reading up on a few forums on how to change the HT wires on the coil. Also, need to do some ground testing as I am sure there might be some problems there also. It did sit idle, untouched for 7 years before I bought it...I wanted a challenge and think I have found it....thanks for advice and opinions...Tim

[rustybronco]

Remove the plug caps from all the coil wires noting their locations so they can be reinstalled in the same positions. Measure numbers 1 and 4 and 2 and 3 coils secondary resistances then post those values in this thread.

[Damack]

New info

Rusty, the readings with out the caps are 12.4 1 & 4, and 12.2 2 & 3. I already post the other readings which seemed to have been with in tolerance. Please let me know if these are not correct, because the manual calls for 31-33 with the caps on, if I allow for the 5k each cap, then I should have been reading 21-23 without the caps. I haven't had time these past few day to devote to it, but will be cleaning ground and other important connections tomorrow to see it it will help. The spark is so weak, I am suprised it did run and seem to be running fairly nice for a short period of time. I guess i am saying that because I did spend alot of time on the carb and might have it pretty darn close...Lol. Again let me know what you think and thanks...Tim

[rustybronco]

As I recall those readings you have are a little low. I've locked up the garage for the evening, but give a few minutes after I get home tomorrow and I'll measure the ones on mine.

The coil that read 32K has bad plug caps...

[Damack]

Yes, only one of the old caps read near 5k, 2 read at around 9 and the worst one read around 14k. These were the ones one the bike during my first reading, which would explain the skew in the numbers. On thing though, the new NGK caps do seem to fit losely, even though I have been reassured they are the proper cap for my bike. Again thanks

[rustybronco]

Didn't get a chance tonight to measure. Be assured I haven't forgotten about it.