Hi all.

I'm sorting through a 98 Road King I bought earlier this spring. I've put about 700 miles on it so far. Had to change the front wheel bearing and found the rear rocker box is leaking. No big deal. But last week the battery went flat. I wasn't getting charging voltage at the terminals with the bike running.

I tested the stator. (single phase, two wire unit) No open ground and it's giving 39 volts AC at 2k rpm and 56 volts at 3k rpm
I've installed a new Drag Specialties rectifier/regulator and a new battery.

Now this is what I get:

Battery at rest, bike off 12.8 volts
Bike running at idle: 12.5 volts
RPMs at 4k: 12.64 volts

It seems to be getting something from the regulator because it if i run it and rev it with the stator unplugged, it stays a steady 12.4 v

What to check next?

Video here:

 

Have you tried the steps Hess outlined in this post ?

https://www.hdforums.com/forum/evo/8...ng-system.html

 

You regulator is not working.

 

Is your digital voltage meter accurate?
Can you test DC voltage again with another meter?

 

At 12.8 that battery is also strong...and If it goes Up when shut off.. that regulator simply is Not working..
leave the regulator attached, but isolated from ground.. Do Not run very long at all tho..measure output to Battery without any Ground Shunt from regulator... If still under, say 13.8-14+ then, regulator NFG

 

Make sure regulator body has a good clean ground to frame and/or engine.

Otherwise, you got a bad regulator or your connections from stator to regulator are not making good contact. Stator to regulator plug is a common weak point on evos.

Drag specialties products don't impress me but sometimes you have no choice.

If you need a new regulator get one from Cycle electric or Comp-u-fire.

 

Just a thought, is the stator plug fully through the crankcase? I have seen a couple of new installs where they couldn't get the plug all the way through and the contacts weren't contacting.

 

Check the connectors above the regulator on the frame in the plastic box for problems (from stator to voltage regulator) for problems,

then pull the seat and check the positive side from regulator to main fuse for power, through the main fuse to the battery/bike side of main fuse (in case main fuse is bad and needs to be replaced), and them next to main fuse on frame, check the negative side of the regulator wire to the engine chassis ground post for corrosion or loose nut/
Main fuse looks like this in clip holder, with voltage regulator wire on copper side, and rest of wires down line to bike and battery, on the silver side. and is located on frame just in front of battery when frame Y's, not down on side of bike under side panel where rest of fuses are instead.


Note,98 road king does not have plug connector at engine case, but stator wire are longer for better connection point into plastic box above voltage regulator on frame for connection points between stator and voltage regulator.

Also, wire off silver side for main breaker, goes to starter solenoid, to connect up to main battery cable off battery ,on the same starter post as the red wire off the main breaker. So if you do have higher voltage at main copper post, but not to battery, check the wire from silver post on the main breaker, to starter solenod that hooks that power to battery cable.battery on the positive side.

.

If all that check out, you have power from the stator in A/C, but engine started and your don't have higher power to battery than before engine was started, then voltage regulator is the problem child. Also, check the voltage at the battery with revs to about 3K, and if you have over 14.2 volts at the battery, voltage regulator is bad and just a mater of time before it cooks that battery from over voltage it.
To add, check both the battery voltagem and since you have the seat off, check the voltage at end of regualtor wires to main fuse and engine ground as well.

For new voltage regulator, either oem or cycle electric.
The cheap voltage regulators off amazon/ebay, will be chasing your tail, if you can get it last a year.

If your going to put more electrical load on the bike, then may want to upgrade to cycle electric three wire stator, and mosfet voltage regulator kit.
Not only does it put out more power at full tilt, but puts out higher voltage at idle to keep the battery charged at stop and go traffic.

And just a FYI, running a battery that is about half dead, is a quick way to burn up not only a voltage regulator, but stator as well.
So get into the habit of checking battery, and replacing it once it starts to die with much lower CCA than list as..

 

I just went through this on my 95 RK. Battery voltage only at 2,000 rpm. Regulator/rectifier tested good. 42 VAC from the stator at 2,000 rpm but it was shorted to ground. Replaced the entire system with Cycle Electric 50 amp 3-phase kit. Spendy but quality made product.