Scratching my head over a voltage problem By scooteraddict (Read 1,229 times)

[scooteraddict]

So here I am, scratching my head over a problem that I thought I fixed.

A while back, I had to replace my stator due to a bad coil. (read at thescooterprofessor.proboards.com/index.cgi?action=display&board=250classchinese&thread=1854&page=1#12215) Well what is plaguing me know is that my auto-choke is not working. When I take a reading, I get like 1.9 volts or so. Thinking that I had not installed the connectors correctly, off came the plastics. Every seem fine but the odd thing is I'm getting strange voltages. For the output direct from the R/R, I am getting 14.7 volts. Through the diode, 9 volts.

Now without the stator plugged in, two things happens. One is I get the correct volts at about 40+ volts and the bike actually revs higher. As soon as I plug the stator back in, the RPM's drop. Weird?

With testing the voltage with the R/R plugged in to stator on the yellow wires, I'm getting around 14, 9 and 1 volt. So my question is, can the R/R be bad? Could the R/R have cause the stator to go bad or did the stator cause the R/R to go bad?

Any thoughts?

[justbuggin2]

yea i think you need to replace the R/R you should get 40+ volts from all the leads from the stator now with the stator unplug the motor can rev higher than with it pluged up as there is no load from the stator afecting the flywheel as you add a electrical load the magnetic field will increase causing a higher drag on the flywheel hopes this gives you the help you need and yes the R/R is the problem

[tvnacman]

Can you post a pic of the regulator?

John

[scooteraddict]

Here is a picture of the r/r



This is on a mc54 250B style bike.

[JR]

With testing the voltage with the R/R plugged in to stator on the yellow wires, I'm getting around 14, 9 and 1 volt.

Major concerns here so I'll ask questions?

Your tests AC or DC voltage readings?
Are these readings to ground or from yellow to yellow?
Are these readings with the R/R unplugged and on the yellow wires only from the stator?

The test for the stator is simple, unplug the R/R and I label the 3 yellow wires 1,2 and 3 and then test them in this sequence

1 to 2
1 to 3
2 to 3

This is a 18-coil 3 phase stator and with the engine revved to about 5k RPM or better the readings should be 60Vac or better on each leg, if not then the stator is toast.

All three reading should be very close to the same and your reading are all unequal, not good.

JR

[cruiser]

JR has brought up some good points. Volts are either AC (what comes out of the stator) or DC (the output of the R/R or battery voltages). So when stating voltage readings they should look like 12 VDC or 12 VAC.

A reading of 14.7 VDC directly out of the R/R is normal and indicates a good R/R. You should also read very close to that at the positive battery terminal. I don't understand a 9 volt through the diode reading. The blocking diode or relay conducts when the engine is running. The voltage drop across the conducting diode might be around .6 or .7 VDC so that you should still see over 14 VDC at the battery positive terminal.

The auto choke is fed VAC off one winding of the stator and gets no voltage from the R/R.

If the R/R is putting out 14.7 VDC, then there is nothing wrong with the stator.

If at least 14 VDC is not present at the battery positive terminal when revving the engine to 5000 rpm, then you have a bad blocking diode or bad connections in the charging circuit.

Here's how to check the auto choke:

thescooterprofessor.proboards.com/index.cgi?board=afcall&action=display&thread=255

[justbuggin2]

Jr he has already replace the stator as one coil was burnt big time i think when his old stator burnt out it got the R/R

[scooteraddict]

Sorry if I didn't mention it but the yellow wires were measured with the meter on AC and across each wire, not the ground. For the R/R output wire, these were measured with the meter on DC.

Now if I,m getting no more the 2 volts to the auto choke, I can only think that the R/R is bad / shorted internally. Now being frustrated, I ordered a R/R to see if this is the problem.

Now one test I didn't perform is to test the voltage on the yellow wires without the R/R output wires connected. If I get the same results, then I know for sure that its the regulator.

[tvnacman]

You should have checked with me before you ordered the regulator . I have many of thoes regulators in stock .

John

[scooteraddict]

You know, checking around for a R/R, you wouldn't believe how many different ones I found for the 250cc engine. I had to be careful due to the wire connectors. The one I have on my bike has six wire. 3 wires each in two different connectors which one is a 3 wire connector and the other a 4 wire connector both being female.

When I decided to purchase a R/R, I went to the scooter cross reference section and looked up the one suggested. This one wouldn't work for me since it has a 2 three wire connectors which one is a male and the other a female.

Where I found the one I needed was on Monster scooter parts for a price about the same as the one suggested. With researching further, I found one as chip as $22 but you know what they say. You get what you pay for.

I will try it tonight and let you guys know.

Cruiser:
I understand the principals of the auto-choke but if you are only getting 1 volt AC to the unit, it just won't heat up to allow it to close. Basically what I'm saying is that, yes I did have a high equal AC voltage when the stator was unplugged from the rest of the bike. When plugged in I was getting all kinds of weird voltages on the yellow wires where one wire had only 1v AC. This is not right and sounds like this wire might have been grounded within the R/R. Even the output of the R/R was not where it should have been.

[JR]

As Cruiser stated the autochoke ties into one of the yellow legs from the stator and the R/R has nothing to do with it's voltage. If you're only getting 1v to it then I guess it's possible the R/R is internally shorted to drop the voltage but if this is the case then you beeter not run the scooter anymore with the R/r plugged up or you'll have another burnt up stator. But 1v makes me believe you've got another burnt stator?

Again I'll stress the stator test MUST be done with it unplugged from the R/R, voltage tested from leg to leg and on AC. The voltage MUST be 60Vac or higher, all 3 legs equal and if not then it's time to tear it apart again.

JR

[tvnacman]

I test my parts and can beat the price you posted. But it is done already. Do as suggested by JR and check the stator. I think the regulator is an exact replacement for what you have in your scooter.

John

[scooteraddict]

Well the verdict is in. I got the new R/R and just installed it. turned the bike over and tested the voltages. Both AC and DC.

With the bike running and all wires connected, at 2000 rpm's, I was getting 27 volts AC on all three yellow wires. Testing the yellow wire at the auto-choke, the voltage was 13.7 AC to ground.

At the battery, I was getting 13.7 volts across both terminals and the same for both output wires at the R/R. To me the regulator was bad.

A while back the I had a problem with another auto-choke where the wires fell apart due to where the plastic tubing was sealed over the wires. I can only think that the two wires shorted out and shorted the regulator which then cause the stator to burn up.