Extract from a scooter forum, submitted by Disco Dave.
STATOR VALUES, HOW TO TEST USING A MULTI METER
The LML stators are identical except for the push connectors to the Piaggio versions. The following tests can be carried out to a Piaggio Vespa stator in exactly the same way. In a seperate posting, he says that Lambrettas should be the same.
THREE IGNITION WIRES:
1. Green (LT)
2. White (EARTH)
3. Red (CDI trip wire)
TWO LIGHT WIRES:
4. Black (EARTH)
5. Blue (UN REGULATED AC) (the more you rev the engine, the more voltage it makes)
To test the ignition (set meter to resistance ohms)put your black probe to the white cable (earth) and then make circuits with your red probe to:
1. Engine case (should be short circuit or less than 1 ohm), if not you have no earth continuity.
2. Red wire (should be 93-120 ohms), if it is outside of this your pickup (halls effect sensor) has "gone".
3. Green wire (should be 450-540 ohms), if values fall outside of this your single ignition coil winding is damaged.
To test the lighting groups put your black probe to the black (earth) cable, then:
4. Test to engine case, again this should be a short circuit less than 1 ohm.
Last test on blue cable, start engine, set metre to AC voltage metre.
5. On engine idle it should be pumping out minimum of 21-38 volts at 600 rpm + you can get peak voltage to these values on a good kick of the starter pedal if you take the spark plug out first.
All these values are common on all electronic vespa stators. In addition to the above electrical tests you should physically inspect your stator. Look for breaks in windings, loose studs, dry soldered joints etc.
Page updated 21/10/2012
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