Kymco S125 no spark By jomama (Read 11,771 times)

[Kaveman]

The spark gets triggered when the flywheel goes over the magnetic trigger switch mounted on the crankcase . IT's a part of the stator assembly . I would check the stator assembly just to be sure that isn't part of the problem. The tech section in the electrical folder has a pdf on how to do that . My scoot ran into a simmilar issue in July and after runnig diagnostics with the help of sprocket and Bashan , it was determined that I had to replace the stator to fix it !

[Bashan]

Yes, the pick up and trigger that Will and Sprocket are referring to is the pulser. Is there some way you can get us a copy of that schematic you're going by? Take a pic and post it on Photobucket maybe. I looked online and found some similar diagrams to your scooter and there is indeed a "switch" hooked up to the CDI that could complicate things immensely. I think you've got a bad CDI or trigger coil, that's my impression so far. How much are parts for these scooters? Rich

[sprocket]

On scooter the trigger bump is on the flywheel behind the fan...not the crank.

Yes, the same thing... pulse coil or pick-up coil or trigger coil.. it is actually a Hall effect sensor or a transducer

On the GY6 there are one or two wires.. the green wire is the ground...

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[jomama]

OK Lads, I ust checked the pulser coil unit wire and it reads .4 Vlt AC. I guess its bad because the CD i have says 1.5 Max but i dont believe it even spscifies AC/DC . I am going to have my neighbor come over and see if he can figure out how to post the schematic I have from the CD. One thing i have found out is the model 125 and S125 are WAY different . In the beginning i assumed the S designation only refered to plastic body parts for styling. When you compare the schematics there is a big difference. The funny thing about the schematic for this S model never shows the 7th wire . It connects to a similar looking unit although slightly smaller than the CDI . Now I am fairly convinced the pulser coil is the culprit because of the border line reading and will search about pricing one .

[Bashan]

Everything that comes out of a scooter stator is AC voltage because the magnets in the flywheel pass by the coils in the stator windings with N and S poles pushing the electrons back and forth. This applies to the trigger/pulser/whatever the hell you want to call it coil. Nothing is DC until it gets to the rectifier and is converted. If the unit on a scooter produced DC it would be called a generator not a stator. A DC CDI still gets it's trigger pulse via AC, the difference is in the fact that it's power for the spark plug coil charge comes in DC. So when you're testing your trigger coil make sure you're testing AC on your multi. Sorry, I had a tripple latte with lunch. Rich

[sprocket]

.4 volts on the GY6 pick-ups is OK but marginal...some say that CDIs will fire with .1volts but that have not been my experience.

The upper limit max voltage is meaningless

[Bashan]

How did you test the voltage from the CDI to the coil? Try this and see what it gives you:

• Unhook the wire that runs from the CDI to the coil at the coil.
  
• Set your multi to AC and put the red probe in the end of the wire.
  
• Get the black probe hooked up to the exposed connector on the coil.
  
• Make sure your killswitch is set to run.
  
• Turn on the key and crank the engine.
  
• See what the multi reads.

Try that and let us know what it does. Rich

[jomama]

Rich, The test shows ZERO volts.

[sprocket]

Well what is the voltage to the CDI.. like for the ignition.. it should be over 50 to 100 voltsAC on an AC set-up...I'm trying to determine if the stator is at fault or the CDI....

[Bashan]

I agree with Sprocket, it's imperative that the CDI be getting adequate voltage from the stator. On my GY6 it's 50 to 100v AC. It's got to have a pulse coil voltage of around .5v AC to fire the CDI (Buggy Depot says minimum .05v but I doubt that). If it does have those two things in place I'll get about 30v AC off of the multi in series from the CDI to coil. If I don't I know my CDI is bad. Now on the Kynco with the additional components, I'm not sure. Here's the thread where I performed this test on my own scooter. It doesn't matter if you clip the black multi lead to the coil or a frame ground because there's almost zero resistance on the primary coil winding. You're not testing the coil in any way, just the CDI output. Rich

[jct842]

sounds like a gy6 chinese is easier to service than kymco, and we all know there is a bushel basket of parts at all the online g6 dealers. I know i would much rather deal with a chinese gy6 than either of the two yamaha scooters i have. after i determine a part is bad then i have to search out who has it for less than dealer list. parts for yamaha usually take two weeks where most gy6 takes 5 days or so. john

[sprocket]

ya I agree jct842... Syms and Kymcos and Yamahas etc are basically 'dealer fix' scooters. They are becoming even more so with weird black boxes that you need special diagnostics to read.

I think the Chinese GY6 is one of the last 'owner fixable' machines... hopefully they will be around in the next 10 years...and they don't start slapping on ECU and EFIs...

Keep it simple stupid is my moto!

[jct842]

the part that gets me the most is that so called perfect scooter takes so damn long to find and get the parts; the last part i ordered, a brake caliper bracket for my 150, it is not a normal part that wears out too, so the expectation for any dealer to have it is low, it came in maybe 4 days after an internet order with card, no phone calls or anything like that. had it been for a yamaha I would be waiting yet 2 months later and a $70 part instead of the $13 I paid for the chinese part.

if the efi ever dies on the big yamaha I will slap a carb on it and strip off the wiring harness.

john

[jomama]

I am still at it here. How to check the voltage from the stator. I have 2 wires. Pink & Yellow. How should i hook up the tester while cranking the engine?Check each wire seperately through the meter to ground or check between each? I dont want to short anything out here.

[Bashan]

Here is the ignition system PDF for Jomama's scooter. It is a bit of an odd duck. Rich