Question about Harley Davidson XLH 1000 Sportster Motorcycles

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How do i check if my regulator rectifer is working on my 1989 xlh 1200 sportster i have put voltmeater on battery dc and reved bike voltage at 12.34v dose not move but turn bike off volts go to 12.8v ,i know regi reck is ac .XLH 1200 .

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You need to check the output of your alternator. Unplug the regulator from the wires that come from your alternator. Put your meter function switch in AC VOLTS, 50 VOLT range. Start the engine and bring it to a high idle. Insert the meter leads into the alternator side of the plug. It doesn't make any difference which lead goes to which contact because you're measuring AC voltage. You should be reading 25 volts or higher from your alternator.

If your alternator is putting out 25 volts or better, and your battery is fully charged but only reading 12.3 volts, then your regulator is probably bad. It should be reading 14.5 to 15.0 volts when checked with a fully charged battery.

Make sure the regulator is grounded well to the frame and all connections are tight and clean.

Good luck

Posted on Oct 11, 2010

Testimonial: "thanks for info not had bike for to long , after takeing the seat off i can see that a gremlins done the wireing ."


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I have a 1989 XLH 1000 sportster. For some reason the battery starts draining while sitting turned off and while driving it. I replaced the generator and added a gen. mounted regulator. However it...

first did you polarize your generator ? you must do this other wise your generator can discharge rather than charge , second if your voltage regulator is bad ,and yes you can get a bad one right out of the box it will not charge and when it sits it will dis charge you can check your regulator by using a volt meter unplug your voltage regulator one lead to ground one lead to your plug if there is any more than .5 dc volts your regulator is bad ,but more than likely your generator needs to be polarized or it will not charge,any early service manual will cover how to do it

Sep 09, 2013 | Motorcycles

1 Answer

2006 xl 1200 0nly getting 13volts dc at battery new regulator and battery my stator is putting out 20 volts ac at idle reved is 100 volts ac is that to much or normal ?

Make sure that your battery is fully charged when taking doing these test and the bike should not be at idle RPM, it should be at about 2000 RPM or a little better. You should be reading at least 25 volts AC out of the alternator and between 14.5 and 15.0 volts DC across a fully charged battery. If it's getting 13 volts at idle, it will probably come up a bit when you increase the engine RPM. It might take a minute or two for the voltage across the battery to peak out. If it doesn't, check the ground on the regulator, it must be grounded correctly. I usually put a star type lock washer between the regulator and the frame on both mounting bolts to ensure a good ground.

Good Luck

Apr 10, 2011 | 2006 Harley Davidson XL 1200 C Sportster...

1 Answer

2 new batteries, each died in a months time. Do I have a bad altanator? 91 Sportster 1200 xlh

It's possible but let's do a little mechanicing first.

You need to put a FULLY charged battery in the bike. Then, connect a DVOM (digital volt ohm meter) across the battery by connecting the meter's red lead to the positive battery post. Then, connect the black meter lead to the negative battery post. Put the meter's function switch in 'DC VOLT, 20 VOLT OR GREATER scale. Make sure the meter is in DC volts. You should read about 12.3 volts. Start the engine and bring it to a high idle. The meter should slowly build up to between 14.5 to 15.0 volts. If not. proceed to the next step.

Look from the right side of the bike just behind the rear cylinder and just in front of the starter and you'll see a plug. If you can't find it this way, follow the two wires from your voltage regulator back to the plug. It'll be a round looking plug on most Sportsters. Unplug the plug. Look inside the plug half that comes from the engine and you'll see two metal connectors. This is where you're going to test the output of the alternator. First put the meter's function switch in AC VOLTS, 50 VOLT RANGE. Since we're measuring AC voltage on this test, it makes no difference which meter lead goes to which metal connector in the plug. Start the engine and stick a meter lead into each of the metal pieces inside the engine half of the plug. With the engine at high idle, you should read at least 25 volts.

Now, If you don't have the 25 volts at the engine, your alternator is bad. If you do have the 25 volts or more at the engine but not the 14.5-15.0 at the battery, your regulator is bad. I hope this helps,

Good Luck

Feb 03, 2011 | Harley Davidson XLH Sportster 883 Deluxe...

1 Answer

I am having problems keeping charge on my 2000 Suzuki Marauder GZ250. Would this be the alternator?

Instead of a blind suspicion it will be good to have the confirmation done on the bike charging system. Use a multimeter to check the voltage with the engine reved. The voltage must go up to stay above the level of the battery voltage. If so the alternator should be good, if not the alternator votage ( AC)and the rectification/regulation must be checked. Once the battery charge is establised the battery drain current must be checke on switch OFF. Check if there is any stray voltage reducing the voltage, if so trace to find / disconnect the suspected circuit.

Nov 01, 2010 | 2000 Suzuki GZ 250 Marauder

1 Answer

I have an '06, 1200 Sportster Custom with 1300 miles on it. The Check Engine light comes on sporatically. I checked the trouble code, and it says the battery voltage is too high. Does this mean the voltage...

Test the output voltage. With a fully charged battery, connect a digital volt ohm meter across the battery. Red meter lead to positive and black meter lead to the negative post. Put the function selector switch in DC VOLTS, 20 VOLT range or there about. Start the engine and bring it to a high idle. The meter shoud read out a voltage and start to climb. If the battery is fully charged, it will settle down in just a short while. It should read between 14.5 and 15.0 volts. If it's higher than this, the regulator should be changed.

Good luck

Sep 23, 2010 | 2006 Harley Davidson XL 1200 C Sportster...

1 Answer

1993 Harley Sportster 883 Batt. is tested and good, generator tested and good, regulator is tested and good, no drwa on batt with ignition off, Charging system putting out 13.5 VDC at 2000 rpm. At idle...

You've already spotted the problem. 13.5 volts is not enough to keep the battery charged. It will slowly lose it's charge. You should be charging at 14.5-15.0 volts.

Check your regulator output. Look just behind the base of the rear cylinder and you'll see the wires coming out of the primary that go to the regulator. There's a plug in the line somewhere. Unplug it. You'll be measuring the output of the alternator so you'll be dealing with the wire on the alternator end of the plug. There are two metal contacts in the plug. You'll need a DVOM (digital volt ohm meter) to do this test. Set the meter's function selector switch to AC VOLTS, 50 VOLTS or greater. Start the engine and bring it to a high idle. Insert one meter lead into each metal contact. It make no difference which lead goes where as you're measuring AC voltage. Your meter should read at least 25 volts or higher. If not, your stator is bad.

If you read 25 volts or more, your regulator needs replacing.

Good Luck

BTW: Early 1984 was the last year for a generator on the Sportster. Late 1984 to present, the bikes have alternators on them. Much better than the old generators. Much better.

Sep 13, 2010 | 1993 Harley Davidson XLH Sportster 883

1 Answer

79 sportster charging system voltreg and generater keep going out with new battery

This is unusual since the generator is usually pretty tough. I've got one question. Are you properly "polarizing" the generator? To "polarize" the generator, you need a piece of wire that will reach from the battery to the generator.

"With the generator on motorcycle and connected to regulator, connect one end of a jumper wire to the generator armature terminal. Momentarily touch the other end of the jumper wire to the positive terminal of the battery. This restores the magnetism, Remove the jumper."

This is directly out of an H-D service manual. The 'polarizing" procedure should be done anytime any part of the charging system is removed from the bike. Since a generator produces a DC current, this insures that the current is of the correct polarity.

Also, make sure that the voltage regulator that is bolted to the frame is well grounded. It depends on this ground to regulate the voltage. We usually put one of the "star" type lock washers between the regulator and the frame on each of the mounting bolts. The teeth on the washer dig into the frame and the body of the regulator providing a good ground. And, make sure that you've got the wires properly connected. The green wire goes to the "Field" terminal and the two tan wires go to the 'Armature" terminal. If you need a complete schematic, contact me directly at

Good Luck

Jun 21, 2010 | 1979 Harley Davidson XLH 1000 Sportster

1 Answer

Battery keeps dying

You need to do a complete charging system test. First, put a battery charger on your battery and bring it up to full charge. The accuracy of the test depends on it being fully charged. You will also need a DVOM (digital Volt Ohm meter) and know how to use it.

With the battery fully charged, connect your DVOM to the battery in correct polarity. Red lead to positive, Black lead to negative. Put the meter in Voltage, DC, 50 volts or higher range. You should be reading about 12.5 volts if you've got everything connected correctly. Now, start the bike and watch the meter. Bring the bike to a high idle, like with the enricher on. The meter should slowly rise to about 14.5-14.7 volts. If it does, then the charging system is functioning correctly.

If it does not, follow the wires from your voltage regulator to where it plugs into the wires from the engine case. In the plug coming from the engine case, put one of the leads from the DVOM into one socket of the plug and the other lead in the other socket. It makes no difference which lead goes where as the output of the alternator is alternating current. Now, put the DVOM in Voltage, AC, 50 volts or higher range. Make sure you put the meter in AC voltage or you will not get a reading. Again, start the bike and bring to a high idle. You should read 30 volts or higher at high idle. If you do, then the alternator is operating as it should.

Now, since the equipment to test the regulator is quite complicated, most mechanics use this method to test the battery and the alternator. If these two components check out good, they simply replace the voltage regulator. I fixes the problem 90% of the time. Good luck

Mar 26, 2010 | 2003 Harley Davidson XL 1200 C Sportster...

2 Answers

I have a 1979 XLH 1000 sportster and I having a charging issue.I replaced the battery and the voltage regulator and had the generator rebuilt and still it will not charge the battery.Ive checked the...

Did you charge the new battery? Did you check the new batteries electrolyte? I have seen many a new battery come off the shelf, dead! Get one of those floaty ball things and check the electrolytes in the battery, every cell, if one cell is dead, it is no good. The voltage sounds a little low but it should charge up. I don't know what size your battery is, but my old sportster had a car battery in it. Never had a problem. But never left the house without a screwdriver either.

Mar 10, 2010 | 1979 Harley Davidson XLH 1000 Sportster

1 Answer

'07 Sportster 883 Altenator problem

Your sportster does not have an altenator, it has a stator and a voltage regulator. What I would do is LOAD test the battery first. Next I would check my stator. To do this there is a plug on the bottom of the right front down tube, on the lead coming from the stator use a muti meter to measure the voltage with the bike running of course. I forget the exact values but as you rev the engine the voltage should climb. If it dosen't you have a bad stator, if it does the voltage regulator is bad. Pray its the voltage regulator, they cost about the same for the part but is much easier to replace.

May 02, 2009 | 2003 Harley Davidson XLH Sportster 883...

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