Autonerdz forums

This UTV (Side by side) came into the shop about six months ago for a no start. We were cranking the engine to try to get the unit to start and the ground wire for the stator started to smoke!

After I tested (with a meter) each leg of the stator, leg to leg and also to ground...the stator seemed to test out good so I figured that maybe the ground wire became weak over the years so I removed the stator and replaced the ground wire with the same gauge wire and reinstalled. The machine seemed to run just fine for a few days of subsequent testing so we called the customer and he picked it up and was happy with the repair.

Just this week it came back for the same problem as we found out. So naturally we used it as an excuse to get the Pico out and I have attached a waveform for you all to see. 

I think what is happening is a failing leg on the stator that is leaking to ground causing the ground wire to get hot due to the short. I believe that is what I am seeing on the scope but this is my second job with the scope so I am all ears to your thoughts.

Thanks in advance!

-Russ

Added a cranking waveform.

Channel A: Stator Leg 1 voltage AC

Channel B: Stator Leg 2 voltage AC

Channel C: Amp clamp on ground

Channel D: Voltage to ground

Redline, dropped a screen print from a KLR, and this stator if it is the old or new is putting out good voltage as it appears, not familiar with this unit the only ones I have tested are 3 leg.

Do see signatures on the ground appear to be coil timed, but that noise might be on any system, ? what does a good one look like..?

Did a lot of testing as of late on shunt typ verses Mofsett and shunt work the stator 100% as apposed to Moffset. Would also look @ what is coming out of the RR if this system employs that type of thought. Is the RR working the Stator too hard, don't know. My captures I did not have a ground channel.

See almost 4 volts hit to ground on these events, and almost 2 amps, but momentarily. The volts might be higher as it looked like it was capped and rotated down, just a hook up issue.

StitchB

Redline, that  is the beauty of this thread, you can get many opinions.

Sending a JPEG, when I stated it looked good I was looking @ the total sine wave, which is about 25 volts.  That said the captures I sent of the KLR are the wave and all of them show from 0 volts up on the sine wave, recorded using DC voltage setting. All leads were on the Stator side of the R/R not on the Battery side.

I have the setting on DC which is where it should be even though recording an AC signal, might not be true for the amp side, maybe need some feed back from other players here.  Also, talk to Tom and Such on this  when testing AC in other things none automotive AC can be dangerous if exceeding the limits, just speaking what I have been told.


I asked if a waste spark which see no reason why a single cannot be. If you notice every other signature is smaller meaning on a wast spark system there is less resistance in the Jug on Exhaust (no fuel) so takes less voltage to jump the Gap, it was just a thought and the RPM for every other hit gave me the 2,000 RPM.

Also an interesting test on alternators is have nothing on the other end such as a regulator, it is surprising what they will put out with no target voltage on the Battery, can be up to 75 volts I have seen on a car, also a nice test just playing around to see what is what.

The legs on the signatures I tend to view as noise, but not always the case.  See it a lot and becomes a gut feel after while. If you want to see if the capture is actually significant click on filter on each channel and see what is left. I did this on yours and the Volts and amps still are there on the ground line which is wrong IMO.

Also this is the first Alt I have seen in bike or car with only 2 legs, usually 3. Think it is done to create a steady line of voltage and not have any drop outs over 360 degrees, JMO.

Fisher, not sure but pretty sure is a big 500 4 stroke, but have been wrong before, but yes agree with your view on it.

RedlinePowersports wrote on Mar 7^th, 2017 at 8:23pm:


Redline, not sure on this but assume ( I know dangerous) when you say charge coil we are talking a capacitor.

Still find it interesting the volt and amp jumps are in correlation to what I feel is firing of the coil. For giggles do another test and run a channel on the igniton could primary and see if the 2 correlate.

I suppose anything is possible except the signatures on the ground wire are always @ ground except during these suspicious spikes which seem (not sure) to be tied to ignition firing. 

The stator wires put out a cycling voltage but no where during thier ups and downs of the sine way does this show on the ground.  I was thinking about this and discussed it with another mechanic, ??? does this unit have a CDI.

If so it is triggered by a second winding (on my KlR) much like a CPS which signals the firing of the coil. But my main thought here is the CDI bleeding back ignition signatures into the ground wire one the stator through the CPS.

The only energy that I see on the ground wire that could make it hot is these signatures which seem to (IMO) time with ignition.  Would be curious to see a known good unit. The problem with the motorcycle section is there are very few players but like diesel will be more all the time as you and a few others are the first to by them for motorcycle specific needs.


StitchB

Gotcha. Now I see what you are looking at. Yes this is a CDI ignition system. I PM'ed you as well, I will be doing further testing mentioned in the PM and I will keep you all posted. I'll post my findings tomorrow or the next day.

Thanks and talk to you soon!