Tip & How-To about Motorcycles
Use a digital voltmeter for best results, I personally like the Fluke brand of meters as they are simple to use and a very high quality tool. With the motorcycle turned off to start with. Set your meter to VDC and place your probes across the battery posts(if your memory is bad write these numbers down). If your battery is fully charged you should see between 12.2 and 13.5 VDC on the meter. Now again in VDC start the motorcycle and note the readings on the meter with the bike idling again you should see around 12.2 and 13.5 VDC slightly increase the throttle speed you should see the reading increase to between 13.5 and 14.5 VDC if this is the case your charging system is working, if you see more then 14.8 to 15 VDC with the bike running around 2000 RPM you have a voltage regulator problem and it needs to be replaced. If you see only battery voltage(meaning no increase from what your reading was with the bike off) you can have a multitude of issues happening.
1) stator could be bad
2) voltage regulator could be bad
3) battery could be faulty
4) you could even have a poor ground
First thing to check would be that your battery connections are tight and clean. Also check all the ground connections I.E The opposite end of the ground cable, also check to make sure that your voltage regulator is bolted tightly to the frame and that the ground connections is clean and free of paint(paint can inhibit a good quality ground).
Second and from my experience in Harley-Davidson this is the most common issue with HD charging systems. Its called a grounded stator. meaning that you have an unwanted ground. Set your meter to Continuity preferablly on an audible setting that will beep when you continuity.
On the left side of the bike as if you were sitting on it at the front of the primary case you will see a plug going into the primary case, this is where your stator is housed and of course we all know electrics and liquids dont mix but HD puts the two together and due to it your HD is destined to use up stators over the years.
With the key off disconnect this plug, now again in continutity,first touch your meter probes together you should hear a tone or beep. now touch one meter lead to any good ground honestly anyone of the primary case bolts should be sufficent then put your other meter lead in either of the 2 holes of the stator plug where it comes out of the primary case. If you get a tone you have a grounded stator and it needs to be replaced. This condition can exsist even if the charging system is still charging so always check for this.
Now on to testing your voltage regulator since we already have it unplugged at the stator(the plug that connects to the stator plug runs back to the voltage regulator. Follow this plugs wiring back to the voltage regulator and find the single wire that runs back to the battery or to the main circuit breaker and then to the battery. disconnect this single wire at the breaker if thats where it goes first. If it goes direct to the positive side of the battery then disconnect it there.
This time in Ohms place one meter lead on the end of the single wire and the other meter lead on either one of the pins that would normal connection to the stator. Note your reading, as a rule it shouldnt be more then 1 - 2 Ohms of resistance through any wire.
From my experience and I have done alot of charging systems for HD over the years.
First thing to go is usually the stator, when the stator goes it usually kills the voltage regulator if not taken care of right away. There is also a test for output from the stator to the voltage regulator and this is checked with all your connections tight and clean. Make sure everything is connected with the exception of the stator plug to the voltage regulator at the primary case.
Now this time your meter needs to be in VAC notice that is Volts AC for this test. You might want a friend to hold the throttle for you during this test. now place each of your meter leads in the plug coming out of the primary case(stator) start the bike up and you should see at an idle around 16 - 19 VAC if you increase the rpms you should see this reading increase as well around 17 VAC per 1000 RPMs so if your holding at 3000 RPMs you should see 50 VAC. If your getting anything below around 40 VAC at 3000 RPMs your stator is not putting out a sufficent amount of voltage and needs to be replaced. When I see this particular condition I always replace the stator and voltage regulator both as there is a good chance the voltage regulator has been spiked or over worked and will fail shortly.
Just to wrap this tip up let me say that before you attempt to change your stator or anything electrical really disconnect the battery first. The fingers you save maybe your own. I hope this helps anyone that may read it even a little bit. Good luck and thanks for using FixYa.com
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