Electrical Diagnosis By Guitarman (Read 1,839 times)

[Guitarman]

As long as I get decent weather tomorrow, I'll finally get to meter it out.

[Bashan]

Dec 1, 2013 7:50:35 GMT -6 Guitarman said:

Am I AC or DC since my headlights do not come on till the bike is running? And does that matter in diagnosing the R/R?

No, I don't think so. Scooters and motorcycle often use AC off of the stator to power up most of the lights. So they will come on when the stator starts spinning. The R/R is involved because it regulates all circuits to 12v. However, is no rectification to DC on those circuits that light up with the stator. Some of the lights come on with the ignition, most notably the brake circuits which are DC. They power the actuator on the solenoid...you know...the pull in the brake handle thing. If your voltages on any of the supply wires off of the R/R are way off from 12v the R/R is probably bad.

[Guitarman]

I'll be on this in the morning, as long as the wife doesn't think of something else I need to do.... LOL

[Guitarman]

Ok, FINALLY!! 12.9 when off and 11.6 when running.
Obviously it's not charging. And equally as obviously, it's either the stator or the R/R. It runs with a dead battery, (if I jump it) so doesn't that mean that the stator is putting out the juice to keep it running? That spark has to come from somewhere....

I didn't meter the R/R because I have to pull more plastic off to get to it. *heavy sigh* I'm really thinking about converting this to a ruckus style bike and just getting rid of most of the body panels...

According to the wiring schematic for my bike, the stator provides the power for the spark. The R/R has no effect on the spark. So the stator must be putting out voltage for it to keep running. It could still be bad and just putting out just enough to run, but it's more likely I think that the R/R would be bad.

[Bashan]

You're correct, the stator provides the energy for the spark and everything else. I know I've gone over this but just let me ramble on, it's easier for me. Here's how it works, the CDI uses either AC or DC going into the bottom of the two connector to make a spark. The trigger coil tells it when to send the burst of energy to the coil. Most GY6s had AC CDIs energized by the R/B wire from the dedicated magneto coil:

Now you see more and more GY6s using DC energy from the battery, via the ignition switch, to power the spark from the black wire. These DC CDI systems use three phase AC power from the three yellow wires off of the stator to power the battery after it's rectified to DC in the R/R, although some also have an AC output wire. Then most components run off of DC power from the battery including the CDI:

I believe all 250s are DC CDIs but with the Chinese who knows. As Alley said, test the wire going onto the two connector and if it's 12v DC with the switch on it's a DC CDI. If it's AC the power wire will carry 50 to 100 AC volts when the engine is spinning.

The AC systems will run without the ignition on once they start because the spark is generated from the dedicated magneto coil which produces the 50 to 100 v AC once the stator is spinning. The only reason the AC CDI GY6 stops when you turn off the key is the killwire grounds out the spark via the ignition switch to the CDI top two connector spot. In a DC powered CDI, the engine stops when the DC power is cut to the CDI at the ignition switch. Yes yes everybody, some DC CDI systems use a killwire into the top of the two connector; I am aware of that.

Now, I got to thinking, I was pretty sure you had a DC CDI like most 250s so why does it keep running after the jump when you have a dead battery? Because the stator is making enough energy and the R/R is keeping the battery up enough to produce spark. That doesn't mean they're OK, it means they're hanging on by a thread. You're stator is probably OK but you can test the three yellows to see. I test mine in series, you can read about it right here. Or you can test between the yellows in all combinations by touching your multi probes as outlined in this thread. If your stator is putting out about 70v AC on the yellows it's youe R/R causing the problems. Let us know if you need more help.

[Alleyoop]

GEEEEZZZZZZZZZZZZZZZZ Guys this is NOT ROCKET SCIENCE.
Just do the following TWO TESTS and you will know RIGHT OFF THE BAT what you have. You may find out with just one of the tests and won't have to do the other.

I GUARANTEE, start the motor and if the CDI is DC and you disconnect the BATTERY it will DIE no TWO WAYS ABOUT IT. If it is AC it will keep running, (THAT MY FRIENDS IS A GUARANTEE).


Quit farting around and find out and all you really need for this test is a 12V Light Tester couple of bucks. If you have to test the stator then you need a VOLT METER.
Alleyoop

Dec 1, 2013 14:41:01 GMT -6 Alleyoop said:

TWO easy means to determine IF your CDI is AC or DC.
1. Check the Bottom Wire on the TWO PLUG of your CDI, with the KEY ON and if it registers 12volts it is a DC CDI.
2. Start your Motor and disconnect the Battery if it is DC your motor will DIE otherwise it is AC.


Remember Guys, when someone says is my Scoot a DC or AC system all it means is the CDI battery Fed(DCV) or Stator Fed(ACV).
The lights can be driven by either the Battery or R/R which converts ACV to DCV. Also they can be a mix of how they are Fed. Some lights may work off the battery and some off the R/R.
Alleyoop