GT350 12vdc w/o battery, ign OFF

[Holeshot]

1971 GT350, no spark, fuse gets HOT HOT when coil white wire is connected (good battery onboard) - orange coil feed is 12v + with ign switch off, pulled ignition switch, STILL 12v +, pulled battery off of bike, STILL have 12v with NO battery onboard! What the!!! I had this bike running good after replacing that coil with an eBay coil. Then it quit, came back with no spark on either side.. This bike appears to be all OE...

[Holeshot]

After sitting overnight, no battery, no ignition switch, STILL has voltage going to coil orange wire!!!

[Holeshot]

After sitting overnight, no battery, no ignition switch, STILL has 12v + going to coil orange wire!!!

https://daveyho.files.wordpress.com/202 ... 700083.jpg

[jabcb]

Any variation or did you get 12.41V for every test?
Perhaps the meter has a memory function or it isn’t working correctly.

[Holeshot]

It's a high end digital meter I've had for 30 years - NO memory function. It was turned off & unhooked from bike overnight. I've been a factory trained, certified, registered Honda/Suzuki/Yamaha dealership tech since the '70s.... Never saw anything like this. The bike IS slightly before my training & very very primitive, no regulator at all. Something is holding that voltage. The new chungese ignition coil is not plugged in,so that's not it. Something in the factory system. That orange wire supplying 12v to coils SHOULD go to zeroV with key off, it does not, even with ignition switch unplugged. Has to be a melted wire somewhere, for that to happen. This bike ran good & operated correctly a month ago when I first got it going.... No way I can charge the appropriate $ for the hours I'll have in this rusty turd.

[datsunrides]

I have something similar happening to a T500. On mine, the orange wire stays hot when I switch the key off, but then discharges after a couple seconds. If I leave the headlight switch on, it kills immediately. Weird. IIRC, there are only 2 things that get power directly from the battery before the ignition switch. The generator and the rectifier. Must be something storing the power in there like a capacitor somehow. I haven’t really looked into why mine does that since it functions fine otherwise.

[jabcb]

This is a head scratcher issue.

Another guess would be that you have an aftermarket digital speedo+tach that has its own battery. But you said the bike is all OE. So that’s not it.
(My T500 cafe build has an aftermarket digital speedo+tach with a clock. Has two V+ connections so that you can use a separate battery to run the clock with the bike off.)

The coils ground thru the points. Check the voltage across the points.
The dwell should be around 180 degrees. So one points should be closed approximately all the time.

Don’t run the bike without the battery — it’s the voltage regulator. Some years ago I disconnected the battery on a 71 T350 to service the points. Got interrupted. After returning I started the bike without connecting the battery. It started right up & quickly burned out whatever lights were on.

I have a collection of Suzuki two strokes. All the aftermarket coils I purchased work fine. But I never bought the super-cheap made-in-China coils.

[Holeshot]

No aftermarket pieces... Went out to shop a bit ago, two days later & checked the batteryless bike's voltage - 8.8 vdc... Started unplugging stuff...

Take a look at this for our answer -->

https://daveyho.files.wordpress.com/202 ... 156725.jpg

I unplugged THAT & voltage went to 0... Then I plugged it back in, attached the battery by jumpers, then removed the battery connection... Back to the same - holding DCV... Now, dìcking around with the h/l switch & h/l beam switch, ALL clicks affect how quickly the above pictured item discharges the voltage it holds on to... And if I move the now dangling left hndlbr sw around, the voltage number goes up & down... We all know what THAT means.... One other note, (battery connected), haven't gotten spark back yet but detected that when the new left coil is connected, the fuse holder connectors immediately start toasting... So, did the bike kill the new coil? Why... Doesn't explain why the left cyl is now no sparky...