GT500 low speed coil

[karl pa]

I lost my low speed coil again,this is my 3rd coil in 8 years.all 3 show around 120 ohms,they should be around 185 ohms,everything else in the magneto tests ok. Just wondering if this is normal, or is mine shorting them out sooner then others.I did put around 15,000 miles on in that time.

[Lorenzo]

Karl I am not an expert on the GT500 so take my words as an input.

The continuity value for the low speed coil, should be 214 homs, not 185 (value apt to the hi speed one);

I would also check that there is a path with the capacitor on the igniter (CDI), by measuring - best with an analogic meter - that there is a little continuity, at first, soon followed by a switch to infinity, between the B/R (from the low speed coil) and the W/bl wire (to the low tension side of the ignition coil), with negative probe to the former and positive one, to the latter.

[karl pa]

Thanks for the input, but if I am correct the low speed coil (large exciter coil) between green wire and ground is 185 ohms, high speed coil (small exciter coil) between green wire and B/R wire is 29 ohms, both coils in series between B/R wire and ground is 214 ohms.
When I installed this low speed coil, it had a value of 184 ohms, I also replaced the high speed coil, it had a value of 29 ohms. It lasted about 3 years until I couldn't start with kick starter, started right up by push start. when I checked green wire to ground I only had 120 ohms, high speed is still 29 ohms.

[Lorenzo]

Do not want to argue and, we probably saying the same thing...

[karl pa]

I received my new primary B coil (32142-15320). Shows 185 ohms exactly. See how long this one lasts.

[gyrocfi]

I am very careful when soldering the coil in. I also use dental floss to tie the wires and coil up then coat it with epoxy. I think it helps with viberation and heat isolation. I hope this doesn't jinx me cause mine continues on after tons of miles. If the bike gets hard to start and Ive checked the plugs I will figure its the coil.

[karl pa]

Installed my low speed coil today,starts right up with kickstarter. Also used your tip on dental floss and epoxy. thanks

[karl pa]

I lost my forth low speed coil, this one didn't have many miles on it. The CDI unit tested ok, but I decided to replace it.
This time I replaced the low and high speed coils and the CDI unit with Rexs speed shop parts, everything tested good, and after installing them the bike fired right up with the kickstart. Hopefully this solves my issues.
The parts from Rexs are advertised to be an upgrade from original, and the price is less than half what Suzuki wants.

[Yorkshireman]

I realize I'm resurecting an old thread here but the content above with the resistance readings is relevant and doesn't need repeating in a new message I believe.
So, my 1976 GT 500 runs but it's not great and it won't idle. It feels like it's on the right cylinder with the left chiming in occasionally. I'm still working my way through it and haven't used it on the road yet. I'm yet to strip and check the carbs apart from renewing the fuel lines and the 'O' rings on the pilot screws cos they were hard from ethanol I'm guessing so I'm concentrating on the electrics for now and I think the sparks are very weak causing poor running. The spark plugs are NGK B8HS and I believe they should be 7's. That's one thing. I've had the multimeter out and the resistance readings for the exciter coils are all a little bit low. I'm getting 203 against 214, 177 against 185, and 65 against 67 for the pulser coil. The charge coils are all 1ohm so appear ok but the reading across the two HT leads is only 9.6 kohms against 12kohms.
As the exciter coils are all within 10% of what they should be I'm thinking the first step would be to change the HT coil and fit the correct grade spark plug or would I be as well changing the exciter coils at the same time??

[karl pa]

I don't believe I would worry to much about the low speed coil, it is basically only used during kick start. Mine would not start when the ohms dropped to around 125, since the ht coil fires both plugs at the same time, if it is firing one side it should fire the other. unless the issue is with the plug cap or wire. I would cut a small bit off the wire and check caps. This ignition doesn't really have good spark. I would go through carbs first.
There was a member a few years ago that had trouble and it ended up being the flywheel magnets lost there strength'

[Yorkshireman]

Thanks for the reply. The resistance between the plug leads is way down suggesting the HT coil is failing and for £40 is a cheap option to just change it. As the other readings are within 10% it’s not worth swapping those components.