I am having trouble with battery going down while riding.

Done a few checks:
Stator output 42V @ 2,000rpm
Stator ground test checked OK
stator resistance 0.4 Ohms
Had the battery checked twice, both said it was good.
I had 12.7V across the post, started the engine with all my lights on and it dropped to 12.2V (12.4 without running lights)... reved the engine alittle and it climbed back to 12.5V.. (should have been around 13.5 or 14V right?)

So What? Since the stator is putting out 42V, The regulator is not letting enough juice back through to the battery is it?

 

I sort of had the same problem, I was not getting but 12.2v at my battery. Took it to HD and they pulled the plug apart just below the voltage regulator and found a bad wire connection pluged it back up and volts at battery went back up to 14.8.

This plug was tie strapped to the front frame just behind the front exhust pipe.

 

This is exactly what happened to me when my regulator went bad.

 

Stator resistance is slightly high and battery voltage too low. 1+ Check your connections. The stator output is good for 2,000 RPM but sounds like it isn't reaching the battery. Below are some tests and values (some you need a powerlink-type testor or inductive pick=up for multimeter) which may be helpful (I leave it to you to decypher!):

CHARGING SYSTEM TESTS

*All tests performed with battery tender disconnected!

1. SYSTEM ID:______________
38 amp: 2001& UP SOFTAIL/2004 DYNA, 3-phase 45 amp:1997-2005 ULTRA 50 amp: 2006 FLT 22 amp: XL exc. 2007 & up, 32 amp, full wave

2. MAX VOLTAGE:__________VDC (13.5-15VDC)
POWERLINK or DVOM CONNECT TO BATTERY LEADS RUNNING REV TO 3K RECORD VALUE

3. MAX CURRENT/VOLTAGE OUTPUT:__________AMP (MINIMUM OF 85% OF SYSTEM RATING)
POWERLINK or DVOM WITH INDUCTIVE LEAD CONNECT TO BATTERY INDUCTOR ON MAIN C.B. {SMALL BLK WIRE TO REGULATOR} ZERO RUNNING REV TO 3K ADD LOAD TO 13V RECORD AMP VALUE DISCONNECT P-LINK (-) TO RESET {MUST BE LESS THAN 15 VOLTS}

4. CURRENT DRAW:__________ AMP
POWERLINK or DVOM WITH INDUCTIVE LEAD CONNECT TO BATTERY INDUCTOR TO BATTERY (-) DISCONNECT STATOR DEUTCH RUNNING REV TO 3K ENERGIZE LOADS RECORD VALUE

5. CURRENT LEFT TO CHARGE BATTERY:__________AMP
SUBTRACT #4 FROM #3 RECORD VALUE

6. MINIMUM REQUIRED: 3.5 AMP


7. STATOR OUTPUT: 1K__________VAC __________VAC __________VAC
2K__________VAC __________VAC __________ VAC
3K__________ VAC __________ VAC __________ VAC
(16-20, 32-40, & 48-60VAC) DVOM ON “VAC” CHECK AT STATOR DEUTCH FEMALE {3-phase: 1-2, 1-3,& 2-3} REV TO 3K RECORD EACH VALUE

8. STATOR RESISTANCE: 1-2_______ 1-3_______ 2-3_______(0.1-0.3 ohms)
KEY OFF DVOM TO “OHMS” CHECKING PINS 1-2, 1-3, & 2-3 RECORD VALUES

9. STATOR GROUND:_______OHMS (OFL)
KEY OFF DVOM TO “OHMS”RED LEAD TO PIN 1, 2, & 3 BLK LEAD TO GROUND RECORD VALUE

10. REGULATOR GROUND:_______OHMS (CONTINUITY)
RED LEAD TO REGULATOR (BARE METAL or GROUND LEAD) BLK LEAD TO GROUND RECORD VALUE

11. MILLI-AMP DRAW:_______ADC
DVOM TO “AMP” SETTING DVOM AT MAXI-FUSE or DISCONNECTED BATTERY (-) TERMINAL RED LEAD TO BATTERY (-) TOWER BLK LEAD TO BATTERY (-) CABLE KEY OFF RECORD VALUE