Tech
FXR Charging System
Every factory FXR charges the same basic way. An alternator in the primary, a regulator on the front of the engine and a 12 volt battery under the seat.
What changed is the output: 22 amps through 1988, 32 amps from 1989.
Which charging system is on my FXR?
| Years | Output | Factory parts |
|---|---|---|
| 1982 to 1988 | 22 ampsShovelhead 1982 and 1983, Evo 1984 on. Same system. | Stator 29965-81A Regulator 74516-86 Battery 65991-82A |
| 1989 to 1994 | 32 ampsNew stator and regulator. | Stator 29970-88A Regulator 74519-88 Battery 65991-82A |
| 1999 to 2000 FXR2, FXR3, FXR4 | 32 ampsSame stator, chrome regulator. | Stator 29970-88D Regulator 74537-93A Battery 65991-82B |
Every FXR: rotor 29957-81B, 12 volt battery under the seat. Harley's current replacements: stator 29965-81C (1982 to 1988), 29970-88D (1989 on); regulator 74519-88B (1989 to 1994). Sources: H-D 1984-86 FXR parts catalog, alternator and battery; H-D 1987-90 parts catalog, alternator and battery; H-D fiche, FXR alternator and battery, 1982 to 2000; H-D 1985 FLT/FXR Owner's Manual.
The parts
Four parts, same places, every year.
- Rotor: the spinning magnet ring on the engine end of the primary. One part number, 29957-81B, 1982 to 2000 (H-D 1984-86 FXR parts catalog, alternator and battery; H-D 1987-90 parts catalog, alternator and battery; H-D fiche, FXR alternator and battery, 1982 to 2000).
- Stator: the wire coils bolted to the engine case inside the rotor. Single phase, two wires out to a plug on the front of the case (H-D fiche, FXR alternator and battery, 1982 to 2000; Rider, "Charge it").
- Regulator: turns the stator's AC into 12 volt DC. Harley's books put it at the front of the engine, every year, on bracket 74529-79 (H-D 1982 FLT/FXR Owner's Manual; H-D 1985 FLT/FXR Owner's Manual; H-D 1999 FXR3 Owner's Manual).
- Battery: 12 volt, under the seat (H-D 1985 FLT/FXR Owner's Manual).
Amps and watts
Amps times about 13.5 volts gives watts.
32 amps is about 430 watts, but only near 5,000 rpm. At 1,000 rpm a 32 amp system makes about 15 amps (Rider, "Charge it").
For the 22 amp bikes, Cycle World listed the 1983 FXRT's alternator at 370 watts (Cycle World, Aug 1983).
So at idle, with the lights on, the battery can be doing the work. More so on a 22 amp bike.
Change years
Few changes, all at the engine end.
- 1982: the first FXRs get the 22 amp system Harley put on its Big Twins from 1981 (Rider, "Charge it"; H-D fiche, FXR alternator and battery, 1982 to 2000).
- Late 1985: new stator screws, and two rotor spacers (29960-85, 29961-85). The 1984 and early 1985 FXRS and FXRT use the older screws and locking plates (H-D 1984-86 FXR parts catalog, alternator and battery).
- 1989: 32 amps. New stator 29970-88, new regulator 74519-88, Torx stator screws. The rotor did not change (H-D 1987-90 parts catalog, alternator and battery).
- 1991: new rotor spacer, 29960-91A (H-D fiche, FXR alternator and battery, 1982 to 2000).
- 1999 to 2000: the FXR2, FXR3 and FXR4 get a chrome regulator kit, 74537-93A, with its own ground wire (H-D fiche, FXR alternator and battery, 1982 to 2000).
The battery
12 volt, 19 amp hours. One battery for every FXR.
Harley's parts books list 65991-82A for every FXR they cover, 1984 to 1990, FXRT included (H-D 1984-86 FXR parts catalog, alternator and battery; H-D 1987-90 parts catalog, alternator and battery). Today's Harley replacement is 65991-82B, sealed, listed at 20 amp hours (H-D fiche, FXR alternator and battery, 1982 to 2000).
The books disagree on 1987. The 1987 owner's manual prints 22 amp hours for the FXRs (H-D 1987 Owner's Manual). From 1988 on, every book prints 19, and the 1988 book singles out the FXRT at 19 (H-D 1988 Owner's Manual; H-D 1990 Owner's Manual; H-D 1994 Owner's Manual; H-D 1999 FXR3 Owner's Manual; H-D 2000 FXR4 Owner's Manual).
The part number never changed, so we go with 19.
Known weak points
What goes wrong, most common first.
- The stator plug. Primary oil wicks up the stator wires into the plug. The pins arc, burn and corrode. Clean it, seat it, and replace a burnt stator (HarleyTechTalk, stator plug seeping; Reddit, FXR charging system woes). See Known Issues.
- A dead stator or regulator. Stators short to ground or break open. Regulators fail. Rotors rarely fail on a stock engine (Cycle Electric, diagnosing alternators; RevZilla, charging system test).
- Low output at idle. Single phase output drops off at low rpm. Lots of idling with the lights on runs the battery down, and a 22 amp bike has less to spare (Rider, "Charge it").
- Mixed parts. After 40 years many bikes carry swapped parts. A 22 amp regulator is not a 32 amp regulator. The plugs differ. With the regulator unplugged, a 22 amp stator makes about 24 volts AC per 1,000 rpm, a 32 amp about 18 (Cycle Electric, diagnosing alternators; V-Twin Mfg. catalog, regulators).
Upgrading an early bike
To get 32 amps on a 1982 to 1988 FXR: new stator and regulator.
Harley's books list the same rotor for 22 and 32 amp FXRs (H-D 1984-86 FXR parts catalog, alternator and battery; H-D 1987-90 parts catalog, alternator and battery), and owners say the same (V-Twin Forum, FXRT battery thread). A worn or damaged rotor still gets replaced. Many kits sell all three as a set (Cycle Electric, diagnosing alternators).
Quick check
- Charge and load test the battery first (RevZilla, charging system test).
- Engine running, about 13.2 to 15 volts at the battery (RevZilla, charging system test).
- Regulator unplugged: stator AC output, resistance, and no short to ground. Then the regulator (RevZilla, charging system test; Cycle Electric, diagnosing alternators).
- Look at the stator plug for oil and burnt pins (HarleyTechTalk, stator plug seeping).
Still being checked
- The original 1982 and 1983 regulator and battery numbers. We have Harley's current replacements for those years, not the 1982 to 1983 parts catalog.
- Police FXRP charging parts for 1984 to 1990. The 1991 to 1994 FXRP fiche matches the other FXRs.
- Export model differences, if any.
- Harley's own factory amp rating printed in a service manual. Owner's manuals do not print it.
Have a page that settles one of these? Tell us.
More
More: FXR Transmission Info, FXR Manuals (wiring diagrams included) and Known Issues.
FXR Archive | Tech | October 2026