voltage to coil measurements--too low?

[Gorminrider]

The kill switch can be problematic -beyond any cleaning you can do, they wear out too. I've had to take them completely apart and um-"rebuild" them. Or (horrors!) actually replace them!

...But perhaps at this point a "refresh" would be nice. How does the bike start and run? That is, If you think the kill switch is causing a "weak spark" and "poor running", just short it out to see if that improves the symptoms.

And then, there's your battery: It's the main factor when starting. If you need to recharge it every time you start the bike, and you are actively riding the bike* it's time to get a new one
A battery that charges up and after resting with no loads for 24 hours and shows 12.3 volts is just about 1/2 its brand new capacity...can be perfectly useful on a bike given they are good everywhere else, except , like an aging parent, likely to fall over when you're not looking. It's on it's way out.

* wait til next spring if you are not actively riding the bike.

 

[Forden]

The kill switch can be problematic -beyond any cleaning you can do, they wear out too. I've had to take them completely apart and um-"rebuild" them. Or (horrors!) actually replace them!

Thanks. I've determined the kill switch is draining a full volt--only found 1/10v loss in a couple other places on the circuit--off the bike the switch shows 2 ohms resistance when switched on. Hard to clean those contacts thoroughly as they are behind the orange switch lever and it's riveted together--I assume you removed the rivets and re-riveted to "rebuild"?

...But perhaps at this point a "refresh" would be nice. How does the bike start and run? That is, If you think the kill switch is causing a "weak spark" and "poor running", just short it out to see if that improves the symptoms.

Bike starts and runs readily, idles pretty well, runs strongest during acceleration and faster cruising, roughest when cruising at low speeds. Good advice to see if shorting out the switch makes a difference, I'll try that.

And then, there's your battery: It's the main factor when starting. If you need to recharge it every time you start the bike, and you are actively riding the bike* it's time to get a new one
A battery that charges up and after resting with no loads for 24 hours and shows 12.3 volts is just about 1/2 its brand new capacity...can be perfectly useful on a bike given they are good everywhere else, except , like an aging parent, likely to fall over when you're not looking. It's on it's way out.

I've never needed to charge the battery, it's always started the bike fine even after sitting for extended periods of a few weeks (and even, when needed, lengthy cranking). I just threw it on the charger since I'd taken it out to take stuff apart. It showed just over 13V after sitting on a 1.2 amp charger overnight. I'm sure you're right it's not peak anymore, but hasn't shown signs of dying.

Even if the rich running proves to be strictly a fuel/air issue, I'm glad I'm learning and taking the time to assess the electrical health of the bike.

 

[Gorminrider]

1 volt loss is too much for sure!

-I assume you removed the rivets and re-riveted to "rebuild"?

Yes, what a factory can make, a man can break.
...a few notes: look up "burnishing contacts" It's a step up from cleaning solvents that generally do nothing but you might even end up with trying to build up worn areas with a coat of solder that can work for awhile.
These particular toggle switches were not great. They seem to get out of alignment somehow. Even replacing them with used parts from another suzuki is not a sure thing...merely as a thought, if you happen to hoard things like home appliance switches ,they have a lot in common and, it might be a place to look.

 

[Forden]

Took the switch apart and cleaned the contacts--managed to break a little piece off the fiber side of the switch but glued it back and seemed to hold. Replaced the rivets with some small screws and nuts but managed to save the spacers between the two sides of the switch.

Now with battery at 12.5v I am getting 11.7 at the coils. So success, if not perfection, yes? Maybe a new battery would show even better numbers.

Thanks everyone!

 

[Forden]

If a switch shows 0 ohms resistance, why would it still lose voltage? My kill switch is still losing nearly a volt (most of what the circuit is losing), despite being disassembled, burnished and fitted with new connections. It was showing 1 -2 ohms before but now reading zero. Should power not flow unimpeded if there is no resistance there?

Thanks all.

 

[pdqford]

Because ohms isn’t the best method for determining voltage loss.

Voltage loss is really dependent on the amount of current flowing through a circuit.

The tiny tiny amount of current your DMM puts out in ohm mode doesn’t really tax the circuit under test.

Load the circuit as it is loaded under normal use, and put your DMM in DC volts mode, with the probes on each end of the portion of the circuit you want to test for voltage drop (i,e, voltage loss), and read the drop on your meter.

And remember voltage drop occurs on both the power side and ground side of a circuit.
A circuit will drop 100% of the voltage available to the circuit.

So, with the coil flowing current, you can put your meter probes on the battery positive post and the coil positive post and read the voltage dropped on the power side of the coil circuit.

Then put the meter probes on the coil’s power post and the coil’s ground post and read the voltage dropped through the coil primary circuit.

Finally, put your meter probes on the coil ground post and the battery’s negative post and read the volts dropped on the ground side of the coil circuit.

The sum of those three readings will be the total voltage available to the circuit.

Your objective is to drop as little voltage as possible on the power side and ground side of the circuit, and drop all the voltage you can across the coil itself. Really wakes up the ignition system ;-)

 

[ajh]

This thread got me checking my wiring on 1982 gs550e (UK bike) as I suspect I also have a bit of a weak spark.
I had 12.4v at the battery and going into the ignition switch but it drops to 11.5v coming out of the ignition switch and goes down to under 10.5v at the coil, turning lights on drops it to 9.7v. (I checked at coils with engine running and it increased a little bit but my multi meter reading was bouncing around a bit)
At the fuses, I again get 12.4 from the battery fed fuse and 11.5 on the ignition fed fuses

Generally, what sort of voltage should I aim for at the coils?
Is it usual to lose a volt in the ignition switch?

Cheers

 

[Brendan W]

This thread got me checking my wiring on 1982 gs550e (UK bike) as I suspect I also have a bit of a weak spark.
I had 12.4v at the battery and going into the ignition switch but it drops to 11.5v coming out of the ignition switch and goes down to under 10.5v at the coil, turning lights on drops it to 9.7v. (I checked at coils with engine running and it increased a little bit but my multi meter reading was bouncing around a bit)
At the fuses, I again get 12.4 from the battery fed fuse and 11.5 on the ignition fed fuses

Generally, what sort of voltage should I aim for at the coils?
Is it usual to lose a volt in the ignition switch?

Cheers

Looks like you are losing a volt at the ign switch and another at the kill switch.
I would be aiming for no more than one volt below battery at the coils.
The internal contacts of both switches are most likely dirty.
Given the age of these machines, losses are usual in one sense.
However they need not be tolerated and cleaning up will improve things a lot.

 

[ajh]

thanks Brendan! Funnily enough checking this I discovered that my kill switch has been disconnected and wires soldered together (I never use kill switch).

 

[Brendan W]

Might be worth looking closely at the solder joint. Check voltage either side. I would almost always us a crimp in preference. If the wires are not supported you have the possibility that they crack where bendy meets not bendy.