Power to coils

[Christopher]

Hello everyone. My gs850 seems to be running on 1 cylinder. I checked the power to the coils with the ignition key on and got 9.5 volts to one coil and zero to the other. What is the correct solution for this. Can i wire them direct to the battery or do they need to be wired through an ignition wire? Thanks for any advice. Please note this isnt the same bike as my other oil leak post.

[Christopher]

Maybe I should ad its a 79 model gs850gn with a boyer bransden electric ignition.

[LAB3]

If you wire them directly to the battery then there will be a constant draw and the battery would go dead. The best possible advice is to get a volt/ohm meter or even a basic test light and check points along the circuit to see where there's a failed connection, burt wire, etc. Do you have a wiring diagram?

[Christopher]

Thanks LAB3 ive got a cheap multimeter and the wiring diagram but im not great with electrics and the diagrams. Ill see how i go lol

[salty_monk]

You can do the "relay mod". Instructions are on BWRINGERS pages. Basically the coils are wired direct to battery through a relay. Original wire becomes the relay switch wire.

[Rijko]

Hello everyone. My gs850 seems to be running on 1 cylinder. I checked the power to the coils with the ignition key on and got 9.5 volts to one coil and zero to the other. What is the correct solution for this. Can i wire them direct to the battery or do they need to be wired through an ignition wire? Thanks for any advice. Please note this isnt the same bike as my other oil leak post.

Maybe I should ad its a 79 model gs850gn with a boyer bransden electric ignition.

If the coils get 9.5 volt, likely the ignition also gets 9.5 volt.
I don't know about the Boyer Bransden but have seen issues with severals electronic ignitions when power drops below 10V.

[unfocused]

If the coil has 9.5 volts then the whole system has this same voltage. Check battery with the key on and verify voltages. If even at 9.5v your battery is weak.

This doesn't explain the loss of voltage at the other coil. The power for both coils comes from the same wire. It just splits inside the harness and out to each coil.

Verify that you've got good testing equipment - meter and test light. Good grounds (coil doesn't need a battery ground) and power...

I did a relay by-pass so I have direct battery voltage at my coils. I've burnt an ignition module by leaving the key on too long so prevent this at all costs.

You do not need the ignition module powered up to test coils on the power side.

[pdqford]

Hello everyone. My gs850 seems to be running on 1 cylinder. I checked the power to the coils with the ignition key on and got 9.5 volts to one coil and zero to the other. What is the correct solution for this. st.

What model Boyer Bransden system do you have?

Some have specific coil’s that are wired in series
A bad coil can leak voltage on the primary side killing voltage to the 2nd coil.

Some systems wire the coils in parallel and the ignition box turns the coil on when appropriate.

See the Boyer Bransden trouble shooting site:

http://www.boyerbransden.com/faultfinding.html

[Christopher]

Update there was a incorect wiring so now both coils getting 9.5 volts. Battery is 12.5v. Could there be corrosion in the switches?