What conditions need to be met for AC voltage from stator?

T

TNStreamerDreamer

Member
I've got my '72 all put together but now I'm not getting my voltage output from the two wires that should go to my rectifier. I had the rectifier wired in and working before moving the Lifan 125 from another bike to this one.

Getting good spark and engine is running great AFAIK. I've removed the rectifier and have been testing the lighting (yellow) and other power lead (red in my case) from the engine's harness. Playing with the engine's green ground cable (not green/yellow neutral indicator) didn't seem to do anything. Does this green even need to be grounded?

@racerx or @OLD CT you guys are my usual go-to gurus, any idea what conditions need to be met to get vAC out of those? Could it be so fragile that something happened inside the magneto or something in the swap?
 
6

69ST

Well-Known Member
Stator output is AC, period, unless it's been reconfigured to a floating ground...in which case, there'd be two leads for each coil array. With no info, have to assume that this motor has the typical 5-coil stator, consisting of a 2-coil array (that powers the charging circuit) and a 3-coil array for the HL, each having one output lead. The other ends are run to ground. To check output, set your voltmeter to AC and the range to 20v (or close to that limit) depending on your meter, insert on probe into the connector of the yellow lead, ground the other, then crank the engine. You should see AC voltage. Repeat the test with the red lead, if that's the other stator output. These arrays are series-wound and act like two single coils. The 3-coil array will have greater output, probably around 30-35w, by virtue of having more more total windings.

FYI, with the engine running, AC voltage, sans load, can easily top 30-50V.
 
T

TNStreamerDreamer

Member
racerx said:
Stator output is AC, period, unless it's been reconfigured to a floating ground...in which case, there'd be two leads for each coil array. With no info, have to assume that this motor has the typical 5-coil stator, consisting of a 2-coil array (that powers the charging circuit) and a 3-coil array for the HL, each having one output lead. The other ends are run to ground. To check output, set your voltmeter to AC and the range to 20v (or close to that limit) depending on your meter, insert on probe into the connector of the yellow lead, ground the other, then crank the engine. You should see AC voltage. Repeat the test with the red lead, if that's the other stator output. These arrays are series-wound and act like two single coils. The 3-coil array will have greater output, probably around 30-35w, by virtue of having more more total windings.

FYI, with the engine running, AC voltage, sans load, can easily top 30-50V.
Click to expand...


Alright, so I have been testing as instructed above. I wasn't getting any AC output from either. Does the green "ground" wire from the stator need to be grounded to the frame? I thought that was just a grounding location for a wiring harness or something. I figured the whole motor is grounded as it is mounted. Just hoping for an epiphany before I opened up and looked at the wiring around the stator.
 
6

69ST

Well-Known Member
This is one of the problems with Chinese engines, so many different flavors that it can be nearly impossible to know exactly what anyone has...without more information. Best suggestion I can offer, at the moment, (and it's not much) try grounding that green lead, or try running one probe to it, the other to red, or yellow, and see what results you get. It is possible...though highly unlikely, that the stator coils are electrically isolated and need the dedicated ground lead. If so, it opens up some interesting possibilities...like full wave DC power. But don't let's go there, just yet.
 
T

TNStreamerDreamer

Member
racerx said:
This is one of the problems with Chinese engines, so many different flavors that it can be nearly impossible to know exactly what anyone has...without more information. Best suggestion I can offer, at the moment, (and it's not much) try grounding that green lead, or try running one probe to it, the other to red, or yellow, and see what results you get. It is possible...though highly unlikely, that the stator coils are electrically isolated and need the dedicated ground lead. If so, it opens up some interesting possibilities...like full wave DC power. But don't let's go there, just yet.
Click to expand...
So I e confirmed continuity from ground wire out of stator. Grounded to stator. Still getting spark. So I have power to CDI and timing. Still not ac from lighting wires out of stator when ground to the engine or stator ground wire.
Am I missing something still? What should I check for if I open up and pull the magneto?
 
6

69ST

Well-Known Member
Just making sure that I'm not missing something...you're doing the voltage check with the engine running, correct?
 
T

TNStreamerDreamer

Member
racerx said:
Just making sure that I'm not missing something...you're doing the voltage check with the engine running, correct?
Click to expand...
Haha yeah.


Okay so I may not have a "problem" after all... I for some reason am only reading volts AC across the yellow and red (or white) wires, rather than voltage from each to ground.
I'm a bit confused as to what's happening there but I do now have DC volts coming from the rectifier when not hooked up to battery. I was reading 14-18v DC at idle.
HOWEVER, I am only reading battery voltage (12.85v) when I measure the positive tied in with rectifier to ground.
I expected that I should read what the rectifier is putting out, the higher of the two?
 
T

TNStreamerDreamer

Member
@racerx
I've been doing some testing. I am not getting voltage across either stator output to ground. I am, however, getting voltage AC across the two power outputs (yellow and White/red). I've confirmed the ground from the stator, the ground to the rectifier and I've confirmed no continuity (short) from the power feeds from stator to ground. This is blowing my mind. Any thoughts?
 
Top