Charging check

1981 csr1000
What should I read across the battery with bike idling at 1000 Rpms?

Not sure about 1000 rpm, but you should get at least 14 volts at 5000 rpm..

Ok I was at idle and checked and I had 12.7. Never got the chance to rev it up. I think my battery is shot. 4th year. So gonna replace it

bromz wrote: 1981 csr1000
What should I read across the battery with bike idling at 1000 Rpms?

depends on load (headlights on etc) and quality of battery, probably 12.5V ballpark. It will drop below the 14V it shouldread above 3k RPM. Even cars do this, you can see your lights dim slightly at idle then brighten as you rev it.

bromz wrote: I think my battery is shot.

Here is how you test a battery: fully charge it with a trickle charger. Pop the plug wires off the plugs. Put a voltmeter across the battery and read the voltage while you crank the starter. If it is above about 9.5V while cranking the starter, it is probably still serviceable.

@ BOUNTYHUNTER

Is that voltage general for a 12v system or specific to that bike. I have a 400 i am doing some trouble shooting on and want to test the charging system.

That depends on the charging system, 1 phase or 3.
Steve

Kodymadro wrote: @ BOUNTYHUNTER

Is that voltage general for a 12v system or specific to that bike. I have a 400 i am doing some trouble shooting on and want to test the charging system.

Every manual I've seen (KZ305/650/750 ZR750 ZX10R ZRex et al). says the voltage at the battery should be about 14 to 14.5 VDC @ 4,000 rpms. Before testing, the battery should be good & fully charged and you should make sure the voltage regulator connector is good & the connections are clean. (I use a Ctek US 0.8 smart charger & VC97 meter).

From a KZ305 manual: If the voltage is above 16 VDC, the regulator/rectifier is defective. If below 14 VDC, check the alternator output and reg-rec to determine which part is defective. The 81 KZ650 manual says the same thing.

If you pop the plug wires off, make sure to ground them or connect them together. It's not good to drive a coil with the secondary totally open. You can easily destroy the coils or the igniter.