Motorcycle electrics

Stator Rewinds

Ducati Electrical Specialist

Ducati SL500 Pantah regulator.
Most Ducati regulators look much like this one, but there are quite a variety of different models. This type has an integral rectifier, and is commonly known as a regulator-rectifier.

This is the SL500 Pantah alternator assembly. We can rewind the stator, but if the magnets in the alternator rotor play up, or if the keyway flogs out, then the rotor must be replaced. Most Ducatis and other modern motorcycles have alternator setups much like this, although the majority of Japanese models have an external rotor which doubles as a flywheel.

The SL500 Pantah has ceramic balance resistors. These are common to all models with Bosch ignition from about 1979 to 1986, including the SD900 and MHR900 and Mille. The same part is used on the BMW car range of the same era.

CDI pickups or triggers can be repaired, which is just as well as they can be quite hard to come by. These units are used by most Bosch ignition models through to mid 1980 or so, and are common to some Laverda and Moto Guzzi models.

The solenoid is a heavy duty switch which transmits the power to the startermotor. This Lucas unit is used on almost all Ducati models from 1978 to about 1987. Generally speaking, if this unit makes a clicking sound when you hit the starter button then it is working. It is cheaper to replace it with a new or secondhand unit than to have it repaired.
If the solenoid clicks when you try to start the bike, but the engine won't turn over, then the problem is with the battery or the startermotor. Or, just possibly, you have a seized motor.
Don't panic, it's most likely the battery. Does the horn work? If the horn makes a flat squark and the lights come on but dimly, then it's the battery.
Don't rush out and buy a new one - re-charge it, and see if the problem goes away. If your battery constantly discharges, seek advice from an auto electrician or a knowledgeable motorcycle mechanic - you may have a wiring fault (not unknown in Ducatis) or a faulty charging system.

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