Stator test - Ex-500.com - The home of the Kawasaki EX500 / Ninja 500R
 
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post #1 of 7 (permalink) Old 12-30-2019, 4:39 PM Thread Starter
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Stator test

I ran a test on my stator terminals with the bike off to check continuity and got 0 on all three prongs. I checked for AC volts with the bike running and at different rpm and got the same reading on 2 prongs but the third was always abt 50% lower than the other 2 which also read sufficient voltage per rpm. Is my stator bad?
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post #2 of 7 (permalink) Old 12-30-2019, 6:11 PM
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yeah I would say so. they can be repaired if you know how. bit of background here >> the stator on the EX is 3 phase unit meaning it has 3 power wires feeding AC current to the RR. on the stator there are 18 coils. 18 divided by 3 is 6 so 6 of those coils feed 1 wire 3 of them a + charge and 3 a - charge. somewhere on the stator there will be a broken wire or one that has become detached. find the break re-solder it should cure the issue. it is easier if you mark the wire with the low readings and work backwards on the stator.

if you don't know how to do this just buy another one there cheap enough.
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post #3 of 7 (permalink) Old 1-2-2020, 3:48 AM Thread Starter
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Kickass! Thank you! Time to get greasy...
 
post #4 of 7 (permalink) Old 1-2-2020, 3:25 PM
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A visual verification of the 3 stator output wires from their solder point to the RR connector, looking for breaks would be advisable (I think thats what @yorkie is suggesting)

Hopefully, a broken connector wire or related connection or insulation will be evident upon disassembly.
Your digging deeper into the actual stator copper windings would be ill advised and likely result in failure, best left to a pro or simply replace the stator.

Just for reference this pic of a 2 wire stator removed from my older Ducati. Without disturbing the insulated copper windings, I upped the gauge of the wiring leading to the RR. Pic is in process, after soldering but prior to final insulation. IMHO this is the cutoff point to going deeper, unless you are a trained pro.

If needed, they can be rewound by a pro such as Ricks (in the US) https://ricksmotorsportelectrics.com/
But (pending some homework) likely cheaper/quicker to replace.
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post #5 of 7 (permalink) Old 1-2-2020, 5:18 PM
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yeah more or less. without getting all technical and put simply. the power produced by the stator and flywheel magnets is AC current which means 50% is a positive charge while 50% is a negative charge. this is rectified in the RR which converts the negative charge to positive giving a steady DC current.

the test the OP has done [the one we all do when issues arise in the charging system] shows up a fault in one of the stator feed wires. because two work perfectly but one is 50% down on power. this means half the AC current going down that wire is disconnected somewhere.

all you can do is trace the wires back to the coils they exit from no further. if the break is inside the coil windings your stuffed. it is a good replacement you need.

however it is possible and quite common for vibration or foreign object to damage or cut one of the wires from the last coil to the feed wire.. if it has you will see it. if there is nothing to see it cannot be repaired.

had exactly this happen to a bike before in that case a small screw from he trigger plate had come loose and cut one of the insulated copper wires where it joined to the feed wire once re-soldered it was fine.

note. if you look at the photo Duc kindly posted you will see each of the feed wires has two wires connected to it one is + the other is - you will also see they go down the side of the stator to the bottom of the coils this is where they break or where they join the feed wire.
all I am suggesting is carefully inspect all the wires you can see in case one is broken. the areas highlighted by red circles and yellow arrows.
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Last edited by yorkie; 1-2-2020 at 5:30 PM.
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post #6 of 7 (permalink) Old 1-2-2020, 5:45 PM
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Just this past summer doing "the Pile" (Triumph 675 Daytona) I discovered a pinch to 1 wire (that 1 wire was getting super hot while running) due to faulty stator installation by a PO. Fixed by desolder/resolder replacing all 3 output wires and associated insulation.

Must be very careful in wire placement and routing upon reinstall, very limited clearances involved to avoid pinching. Note original wiring in proximity to the mount bolt hole (1st 2 pics) then relocated (3rd pic). The bolt head actually pinched, breaking the insulation, exposed copper then shorting. I opted for a silicone jacketed 12 gauge on all 3 legs which worked out well, full length right to the RR.
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Last edited by ducatiman; 1-2-2020 at 5:53 PM.
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post #7 of 7 (permalink) Old 1-5-2020, 4:38 PM Thread Starter
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I thank you all, sincerely. I am confident you all have it pegged. My next step is stator inspection. I will proceed with caution.
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