2004 ultraclassic while driveing the volt meter goes from 14 down to 10and then backe up, does this most of the time while driveing, while stop at idle it stays at 14 lights dont dim or anything. whats going on regulator, stator, alternator any idea

SOURCE: Recently having problems with my 2000 Fatty not

First, take your battery somewhere and have it load tested. Fat Boys are tough on batteries as the battery sits in the "horseshoe" oil tank and is subjected to high temperatures due to the hot oil in the tank. Battery life is typically two years although I've seen some go longer and some not last that long. Have the battery tested before you start spending money.

To check the stator, you unplug the regulator at the engine case. Down inside the plug you'll see some electrical connectors. Connect a DVOM (digital volt ohm meter) to these connectors (one lead to eac pin) and put the meter in the 50 volt or higher range AC voltage. This is important that your meter be set to measure AC voltage because at this point, the voltage is indeed an Alternating Current voltage coming out of your alternator. Start the engine and bring it to a high idle. You should be reading over 20 volts AC. The book says that you should read 12-18 volts per 1000 engine RPM. If your engine is turning 2000 rpm, your meter should read 24-36 volts AC.

To test the regulator, first charge your battery to a full charge. Then connect your DVOM across the battery, red to positive, black to negative. Put the meter in the 20 volt DC range. Start the bike and bring it to a high idle. The voltage will start at somewhere around 12.5 volts and climb to about 14.5-15 volts. This would indicate that the regulator MAY be alright.

Now, have you changed any of the lights on your Fat Boy? I've seen people change and add lights to the point where their alternator could no longer put out the current necessary to handle the load. If this is the case, you may need a higher out charging system.

I don't know where you're located but $260 seems quite high for a voltage regulator.

SOURCE: electrical problems on 2003 harley sportster

You will need good battery before you can check the rest of the electrical system.

SOURCE: voltage reulator puts out 14 volts and engine

It sounds like the voltage regulator is doing what it is supposed to. The charging system should put out between 14-15 volts when the battery is fully charged in your bike.

Now what is causing your engine light to come on is beyond me.

SOURCE: why is my 2006 street bob not charging

If the regulator was replaced and wasn't properly grounded it will not charge.

SOURCE: 2002 FLHTCUI Electra Glide Ultra Classic: What's approx. cost for a stator / regulator repla...

HD = Hundred Dollars, voltage regulator.
Stator replacement = big dollars because labor intensive. The part is around $100, maybe more by now

Sorry