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2003 RM250 low voltage issues

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Hello I'm having some trouble with my sons' bike not producing enough voltage from the magneto assay.. I've performed the ohm checks for the stator coils (G-R= 98 Ohms, R/W-B/R=37 Ohms and the primary ignition coil read ok( W/Bl-B/W=.3Ohms)... However the the output voltage was only 2 volts across G-R and nil across the others with kicked over firmly... I plan to check the case and stator grounds to the bike frame but, I suspicious of the rotor permanent magnet potency.. A paper clip won't even stick to the rotor.. Other bike rotors that I've had to work around in the past all had good magnetism and would make it hard to put the screw driver on the old stators for adjustment.. While await the parts, and checking the grounds,, can anyone offer any thoughts or guidance to the magnetism around the outside of the rotor?? Should you be able to stick a screw driver or paper clip against the outside of it and it stick?

Thanks in advance for your thoughts!

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On the outside of the flywheel, the screwdriver will not be drawn to the magnet very much. On the inside of the flywheel (directly to the magnet), the screwdriver should be drawn to the magnet with a decent force. Nit like it wants to pull the screwdriver from your hand or anything.

The magnet should have no problem holding the flywheel nut & washer (again, inside the flywheel directly on the magnet).

The stator is more than likely junk.

Edited by KPRacing

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make sure you're getting the reading directly from the wires coming from the stator and make sure the kill switch is disconnected from the circuit, make sure the woodruff key is alright but more than likely it's either a bad ground, bad wiring or a bad stator

 

the magnetism should be on the inside of the magneto or where the rotor goes around the stator, i have a hard time believing there is no magnetism but if there really isn't any magnetism or weak magnetism then yea you're not going to produce the necessary voltage.

 

Usually it's an internally shorted out stator coil junked

Edited by 78SuzyQ
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Permanent magnets don't loose their magnetism that easily. It is unlikely that the rotor magnets have demagnetized. 

 

Did you use a peak voltage tester for the voltage test? A multimeter is not capable of reading the voltage from the stator during a swift kick. The peak voltage tester holds the max output voltage of the stator (values in the manual) so a multimeter can read it. They are easy to make. Just need a capacitor, diode, and something like a 200k ohm resistor.

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Thanks for the quick replies! FYI I'm using a Fluke 93 that does have peak recording and all the magneto will put out is 2 volts.. Unfortunately, I'm still waiting for the rotor puller to come but, when it does I'll check the magnetism on the inside! I have the rotor and stator on the way as well as a double barrel approach! 🙂 AndaAll the case and frame grounds are all good.. So when the stuff comes in I'll post an update. Thanks again guys, Happy roosting!

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Thanks for the quick replies! FYI I'm using a Fluke 93 that does have peak recording and all the magneto will put out is 2 volts.. Unfortunately, I'm still waiting for the rotor puller to come but, when it does I'll check the magnetism on the inside! I have the rotor and stator on the way as well as a double barrel approach! 🙂 AndaAll the case and frame grounds are all good.. So when the stuff comes in I'll post an update. Thanks again guys, Happy roosting!

 

That setting on the meter probably isn't going to show you the peak voltage from your stator. I have tried to use just a multimeter with a max voltage hold setting and it could not record the voltage fast enough. The meter just isn't quick enough for the constantly changing AC voltage during a kick. 

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^ a basic multimeter wont be able to effectively but he said he had a fluke basically the best meter out there money can buy

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