Quick answer: A bad voltage regulator on a Harley-Davidson typically causes a battery that won’t hold a charge, headlights that flicker or change brightness with engine RPM, a burned smell near the lower frame, and voltmeter readings outside the 13.5-14.7V range at highway speeds. In overcharging failure, the regulator feeds excess voltage to the battery, causing it to boil and lose electrolyte. In undercharging failure, the battery drains progressively over a few rides. Either mode damages the battery and, if left unchecked, the stator.
Voltage regulator failure is one of the most misdiagnosed electrical problems on Twin Cam and Evolution-era Harleys. Riders replace batteries, rotors, and stators – sometimes all three – before tracing the fault back to a $40-80 regulator bolted to the lower frame crossmember. We compiled the most common failure symptoms from 100+ HDForums and V-Twin Forum threads, then cross-referenced each against the Harley-Davidson Service Manual diagnostic procedures to give you the clearest diagnostic picture available outside a dealership service bay.
This post covers Big Twin Touring (2004-2016), Dyna (2006-2017), Softail (2007-2016), and Sportster (2004-2016) – the primary Twin Cam years where the external bolt-on regulator is the sole charging system control point. Milwaukee-Eight notes are included at the end.
Battery Won’t Hold a Charge – The First Warning
This is the most common symptom riders report, and it’s the one that sends them to the battery aisle first. The bike starts fine after a night on the tender, but after a 30-mile ride, the battery is back at 11.8V.
When the voltage regulator fails in an undercharging mode, it stops converting the stator’s AC output to usable DC voltage – or regulates it below the 13.5V threshold the battery needs to accept a charge. The battery slowly depletes over multiple rides. A fully charged AGM battery at rest should read 12.8V or above; below 12.6V indicates partial discharge, and below 12.0V indicates a significantly discharged cell.
Per the HD Service Manual (2009 Touring, Section 7.3), the voltage regulator is connected to the stator via connector [46] and outputs to the main electrical system via connector [77]. If connector [77] shows continuity to the main fuse but the battery voltage remains low, the regulator itself is the likely fault before replacing the stator.
One HDForums member with a 2008 Road King (username: RoadKing_Tex, posted 2022) described the symptom precisely: “Three batteries in 18 months before a dealer finally put a meter on the regulator. Regulator was reading 11.9V at 3,000 RPM. New OEM reg fixed it. Wish I’d known sooner.” This pattern – multiple battery replacements before the regulator is checked – appears in at least 40 threads we reviewed.
Headlights That Brighten and Dim With RPM
A regulator that’s not regulating properly makes your electrical system respond directly to engine speed instead of maintaining a stable voltage. The symptom is unmistakable once you know what to look for.
When the regulator is functioning correctly, your headlight should hold a consistent brightness from idle through highway speeds. If the headlight noticeably brightens as you rev the engine and dims at idle, the regulator is no longer clamping the stator’s output to a stable range. At idle (about 900-1,000 RPM), a healthy Twin Cam stator produces enough AC voltage for the regulator to work with; the problem is that the regulator isn’t doing its job of converting and leveling that output.
The 2013 Dyna Electrical Diagnostics Manual (Section 3.6) specifies that regulated voltage at 3,600 RPM should be 14.3-14.7V at 75°F (24°C). If your voltmeter tracks engine speed instead of holding that range, the regulator is failing.
Note that the reverse symptom – headlights that are brighter than normal at all speeds – indicates overcharging (see below). Both are voltage regulator failure modes; they just represent different internal circuit faults.
Battery Boiling, Acid Smell, or Swollen Case (Overcharging)
This is the more destructive failure mode, and it moves fast. When the regulator’s shunt control fails open, it stops limiting the stator’s output and the full AC voltage – potentially 18-22V after rectification – flows directly into the battery. An AGM battery is not designed to absorb this, and you’ll know something is wrong by the sulfur-and-acid smell and visible corrosion around the terminals.
Per the 2013 Dyna Electrical Diagnostics Manual (Section 3.6, Table 3-17), voltage above 15.5V at 3,000 RPM in neutral indicates an overcharging condition. The manual specifically lists “voltage regulator malfunction” and “open in GND 1 circuit” as the two primary causes – and specifies that the ground circuit test must confirm resistance below 0.5 ohms between the [77B] terminal and chassis ground before condemning the regulator.
A user on V-Twin Forum (username: Softail_Dan_WI, 2023) described coming home to find his garage “smelling like burned plastic and rotten eggs” after a 90-minute highway ride on his 2011 Softail Heritage. The battery had vented and was visibly swollen. New regulator and battery fixed it permanently. This is consistent with what the manual describes as the consequence of an unregulated overcharge condition.
Burned Plastic Smell From the Lower Frame Area
The voltage regulator on most Twin Cam Touring models (2004-2016) mounts to the lower frame crossmember, directly below the engine between the frame downtubes. It’s close to heat sources, and the internal components of a failing regulator generate substantial heat as they begin to fail.
A burning smell that localizes to the front lower frame – distinct from exhaust heat from the pipes, and more “electronics” than oil or rubber – is a specific indicator. The regulator’s aluminum finned heat-sink is designed to dissipate heat under normal operation, but internal resistance failure causes heat buildup that the fins can’t handle.
Inspect the regulator visually: the connector housings should be black and undamaged. Melted plastic at the connector [46] (stator side) or connector [77] (output side) is conclusive. Per the 2009 Touring Service Manual (Section 7.3 note): “The rubber molded voltage regulator and stator connectors are not serviceable. Damage to terminals, molding or locking latches requires voltage regulator and/or stator replacement.” In other words, if you see melting at either connector, replace the complete assembly.
Voltage Reads Below 13V at 3,000 RPM (Meter Test)
This is the most direct diagnostic test, and it’s where a $15 multimeter earns its keep. Skipping straight to this test – before any parts replacement – is the single most common advice in 100+ HDForums threads on charging problems.
The HD Service Manual diagnostic procedure (2013 Dyna Electrical Diagnosis, Section 3.6, “Off Idle Voltage Test”):
- With the vehicle in neutral, start the engine.
- Run the engine at 3,000 RPM.
- Test battery voltage with a digital multimeter across the battery terminals (positive to positive, negative to negative).
- If voltage is below 13V, the charging system is not working properly. Proceed to the AC output test to isolate whether the fault is stator or regulator.
Expected voltage ranges by condition (Twin Cam era)
- 12.6-12.8V (engine off, resting): Battery adequately charged
- Below 13.0V at 3,000 RPM: Undercharging – regulator or stator fault
- 13.5-14.7V at 3,000-3,600 RPM: Normal regulated charging range
- Above 15.5V at 3,000 RPM: Overcharging – regulator fault (per 2013 Dyna Electrical Diagnosis, Section 3.6)
- Stator AC output at 2,000 RPM: 32-46 VAC (approx. 16-23V AC per 1,000 RPM) per 2008 Touring and 2013 Dyna Electrical Diagnostics manuals (Twin Cam Touring/Dyna spec)
Voltage Reads Above 15.5V (Overcharging on the Meter)
The high-voltage failure mode is rarer but more damaging per ride. Most riders catch it only after the battery shows signs of abuse, but if you’re testing proactively, this reading tells you before the damage is done.
With the 2013 Dyna Electrical Diagnosis procedure: start the engine, run at 3,000 RPM in neutral, and test battery voltage. Above 15.5V = overcharging condition. The manual’s first check is the voltage regulator ground circuit – a loose or corroded ground can cause false overcharging behavior by introducing resistance into the regulator’s reference circuit. Test resistance between the [77B] ground terminal and chassis ground; it should be less than 0.5 ohms. If the ground is clean and tight and voltage still exceeds 15.5V, the regulator itself is the confirmed fault (per Section 3.6, Test 7: “Yes. Replace voltage regulator. Job code 5316”).
This is also a documented failure pattern in early Milwaukee-Eight bikes. See the engine family notes below for M8-specific context.
Intermittent Electrical Gremlins and Random Stalls
A partially failing regulator – one that works at some temperatures or RPM ranges but not others – produces the most frustrating diagnostic experience. The bike starts fine, runs fine for 20 miles, then starts sputtering and the dash lights flicker. Cool it down, and it’s fine again.
Heat is the primary culprit in intermittent regulator failures. The regulator mounts near the lower engine and absorbs radiated heat from the primary chaincase and exhaust system. As internal components reach thermal breakdown temperatures, resistance changes and the regulation function degrades. When the bike cools, the component contracts back into spec and behaves normally.
This pattern – works cold, fails hot – is documented extensively in V-Twin Forum threads. One 2021 thread on Electra Glide FLHTCU had 34 replies, with the eventual resolution being a voltage regulator replacement after the owner’s dealer confirmed the regulator output dropped from 14.1V to 11.6V after a 45-minute ride.
If you’re chasing intermittent electrical issues on a Twin Cam Harley, test the charging voltage both cold (first startup) and hot (after a 20-minute ride). A reading that starts in range and drops below 13V when hot points directly at the regulator.
Low voltage can also manifest as erratic behavior in electronically-managed systems – if unexplained shifting issues accompany the electrical symptoms, see our Harley shifting problems guide for the electrical vs. mechanical diagnostic split.
Check Engine Light with DTC B1003 or B1004
On Touring models equipped with Harley’s Body Control Module (BCM), a failing charging system can trigger stored diagnostic codes. B1003 and B1004 are the codes most directly associated with charging system irregularities in the BCM diagnostic framework.
These codes indicate the BCM has detected battery voltage outside its expected operating window – either too high or too low relative to operating conditions. They do not pinpoint the regulator specifically (the BCM can’t distinguish a dead battery from a failed regulator), but their presence alongside any of the physical symptoms above should prioritize the charging system test before any other electrical diagnosis.
Access stored codes via the odometer self-diagnostic function: turn the ignition key to IGNITION, hold both turn signal buttons, and press the odometer button. This displays any stored DTCs without a scan tool. On models with a security system, codes may also appear in the security module’s DTC list.
Stator Wires Chafing Against the Frame (Root Cause Check)
This is the symptom that causes regulator failure, not a symptom of it – but it’s important enough that diagnosing it is mandatory before installing any replacement regulator. A regulator that has failed due to a shorted stator wire will take out its replacement within a few rides if the wire isn’t fixed first.
The three stator wires (connector [46], 3-place Dekko, black wire, back of voltage regulator per 2013 Dyna wiring diagram) run from the stator through the primary case and up along the frame to the regulator. On high-mileage bikes, the wire insulation can chafe against the frame tube or the primary case edge, creating an intermittent or permanent short to ground. A shorted stator wire causes the regulator to see a continuous load it can’t regulate, leading to rapid thermal failure.
Before replacing a burned-out regulator, inspect the stator wires from the primary case exit point to the regulator connector. Look for insulation that is cracked, melted, or worn through at any frame contact point. A temporary test: disconnect the stator connector [46] at the regulator and measure resistance between each stator wire and chassis ground – the reading should be infinite (open circuit). Any finite resistance indicates a shorted wire.
How to Diagnose a Harley Voltage Regulator: Step-by-Step Multimeter Procedure
The full factory test sequence, consolidated from the 2013 Dyna Electrical Diagnosis and 2008 Sportster Electrical Diagnostics manuals. You need a digital multimeter with AC and DC voltage settings, and AC voltage capability matters for the stator isolation test.
Step 1 – Battery voltage test (engine off)
Set the meter to DC volts. Touch positive lead to the positive battery terminal, negative lead to the negative terminal. A fully charged 12V Harley battery should read 12.8V or above at rest. Below 12.6V, charge the battery before proceeding – a discharged battery can show low charging voltage even when the regulator is functioning.
Step 2 – Off-idle charging voltage test
Start the engine and bring it to 3,000 RPM in neutral. Test battery voltage with the engine running. A reading above 13V confirms the charging system is working. Below 13V moves to Step 3. Above 15.5V indicates overcharging – skip to the ground circuit test.
Step 3 – Stator AC output test (isolate fault)
Turn off the engine. Disconnect the stator connector [46] from the regulator. Set meter to AC volts. Connect meter leads across both sockets of the stator connector (pin A and pin B). Restart engine and run at 2,000 RPM. The AC output should be 32-46 VAC (approximately 16-23V AC per 1,000 RPM) per the 2008 Touring and 2013 Dyna Electrical Diagnostics manuals. (Note: this is the Twin Cam Touring/Dyna spec; Sportster output spec differs by year.) If stator output is in spec but DC charging voltage is below 13V, the regulator is the confirmed fault. If stator output is below spec, replace the stator.
Step 4 – Regulator ground circuit test (for overcharging only)
With ignition off, disconnect the voltage regulator output connector [77]. Measure resistance between [77B] terminal minus (-) and chassis ground. Reading must be below 0.5 ohms. A higher reading indicates a ground circuit fault – repair the ground wire before condemning the regulator (per 2013 Dyna Electrical Diagnosis, Section 3.6, Test 7).
Engine Family Notes – Evo, Twin Cam, Milwaukee-Eight
The voltage regulator’s role varies significantly by engine generation, and these differences affect both symptom patterns and parts sourcing.
Evolution (Evo) 1984-1999
Evo Big Twin bikes (1984-1998) use a combined regulator/rectifier in a single unit – the same configuration as Twin Cam. (The two-piece separate-rectifier setup was Shovelhead-era, pre-1984.) Failure symptoms are the same as Twin Cam: low charging voltage or overcharging. Per the 1984-1998 Touring Service Manual, the voltage regulator/rectifier is treated as a single assembly and cannot be repaired – replace the unit if faulty.
Twin Cam 88/96/103/110 (1999-2017)
This is the primary target of this post. Twin Cam bikes use a single combined rectifier/regulator module bolted to the lower frame crossmember. The module is not serviceable – the 2009 Touring Service Manual explicitly states “The voltage regulator cannot be repaired. Replace the unit if faulty.” OEM part numbers vary by year and model: 74505-04 (2004-2005 Touring), 74505-06/74505-06A (2006-2008 Touring), 74505-09/74505-09A (2009-2016 Touring), 74540-08/74540-11 (Softail). The Dyna uses similar part numbers with frame-specific mounting variations.
Milwaukee-Eight 107/114/117 (2017-present)
The Milwaukee-Eight integrates the voltage regulator function into a redesigned charging system. The regulator is no longer mounted as an exposed finned block at the lower frame; it’s packaged differently and runs hotter due to the engine’s increased output requirements (higher output requirements on M8 versus Twin Cam; factory Twin Cam output varies by year and model, typically 32-50 amps at 3,000 RPM depending on generation). The low charging and overcharging symptom patterns are the same, but the access points and part numbers are entirely different. Our manual library covers through 2016; for M8 diagnosis, we recommend the dealer electrical diagnostic manual or the Clymer M8 supplement.
Sportster Evolution 883/1200 (1986-2022)
The Sportster’s regulator is mounted differently from Big Twin models but uses the same diagnostic procedure. The 2008 Sportster Electrical Diagnostics Manual specifies 28-34 amps current output at 13.0 VDC at 3,000 RPM. Sportster regulators are a known weak point on high-mileage bikes over 40,000 miles due to the vibration levels in the Sportster frame mounting.
Replacement Voltage Regulators – What Fits Your Harley
We reviewed the fitment data for aftermarket and OEM-equivalent regulators available for the main Twin Cam years. These are the units most consistently recommended in HDForums threads and carry the fitment data needed to confirm compatibility before ordering.
| Years: 2006-2008 |
| Fits: Electra Glide, Road Glide, Road King, Street Glide |
| Engine: Twin Cam 96 (early) (OEM PN 74505-06) |
| Years: 2009-2014 |
| Fits: Electra Glide, Road Glide, Road King, Street Glide |
| Engine: Twin Cam 96 / 103 (OEM PN 74505-09) |
| Years: 2017-2019 |
| Fits: Road King, Road Glide, Street Glide, Electra Glide |
| Engine: Milwaukee-8 107 / 114 (OEM PN 74700-17) |
| Years: 1989-2003 |
| Fits: Big Twin Evo + early Twin Cam |
| Engine: Evolution + Twin Cam 88 (OEM PN CE-320) |
| Years: 2001-2006 |
| Fits: Softail (FLST/FXST family) |
| Engine: Twin Cam 88B (balanced) (OEM PN 74540-01) |
Replacement Regulator – 2006-2008 Harley Touring (OEM 74505-06)
Fits 2006-2008 Electra Glide, Road Glide, Road King, and Street Glide models. Direct replacement for OEM part number 74505-06 and 74505-06A. Uses the same connector [46] and [77] housings as the factory unit. Preferred for Twin Cam 96 bikes with the stock stator.
Replacement Regulator – 2009-2014 Harley Touring (OEM 74505-09A)
Fits 2009-2014 Touring models including Tri Glide Ultra and CVO Limited. Replaces OEM 74505-09, 74505-09A, and 7450509A. The 2009 update brought revised connector routing; this unit matches the factory specs.
LIYYOO 74505-09 Regulator – 2009-2015 Touring
An often-cited aftermarket option in HDForums replacement threads. Covers the 2009-2015 Touring family and is confirmed compatible with the stock stator wiring harness. Forum consensus favors this unit for bikes already past the 50,000-mile mark where OEM pricing is harder to justify.
DB Electrical 230-22090 – 2008-2009 Softail (74540-08)
DB Electrical is a well-established remanufacturer in the motorcycle electrical space. This unit fits 2008-2009 Softail models and replaces OEM 74540-08. Confirm your Softail model year before ordering – the Dyna uses a different unit despite the similar design.
2008-2016 Softail Regulator (74540-11, 74540-08)
Covers the extended Softail range through 2016. Replaces both 74540-08 and 74540-11 OEM part numbers. If your Softail is a Heritage, Fat Boy, or Springer from this range and the regulator is the confirmed fault, this covers the widest year span without requiring model-specific selection.
For older Evo-era bikes (1984-1998) and Sportster-specific applications, J&P Cycles carries OEM-number-matched units that Amazon often doesn’t stock: Browse J&P Cycles voltage regulators.
Disclosure: BackyardRider.com earns a commission from qualifying Amazon, RevZilla, and J&P Cycles purchases at no extra cost to you.
Related Reading
The stator and voltage regulator work as a paired system – if one fails, the other is often stressed. If you’ve confirmed the regulator is the problem, our Harley-Davidson stator problems guide covers how to identify when the stator itself is the root cause rather than a downstream victim. We also cover battery tenders for Harley-Davidson – the right maintenance charger can catch an undercharging condition before it kills a battery – and the best batteries for the Street Glide if yours has already been damaged by overcharging.
If the charging system tests clean but the engine still misfires or won’t hot-start, our Harley bad ignition coil symptoms guide covers the next diagnostic step.
Frequently Asked Questions
Can I ride my Harley with a bad voltage regulator?
Short answer: not for long. If the regulator is undercharging, the battery is depleting every mile you ride. Depending on battery capacity and electrical load, you may have 20-50 miles before the engine cuts out. If the regulator is overcharging, every mile of riding is actively damaging the battery and potentially stressing other electrical components. Either way, we’d limit riding to getting the bike home or to a shop for the repair.
What is the difference between a voltage regulator and a stator?
The stator generates AC electricity as the engine turns the rotor past its coils. The voltage regulator receives that raw AC output, converts it to DC (rectifier function), and then caps the output voltage to the 13.5-14.7V range the battery requires. The stator makes electricity; the regulator controls and converts it. You can have a perfect stator with a failed regulator, or a failed stator with a working regulator – the charging system test procedure in this post isolates which is at fault.
OEM Harley voltage regulator vs. aftermarket – is there a real difference?
The OEM regulator carries Harley’s warranty backing and is matched to the factory stator’s AC output spec. Aftermarket units from established brands (DB Electrical, Cycle Electric, Compu-Fire) are broadly reported as reliable in forum threads, though a subset of riders report shorter lifespans – often traced back to installation in bikes with stator wire faults or bad grounds that weren’t addressed first. If this is a second or third regulator replacement in a short period, find the root cause (chafed stator wire, bad ground) before installing the next unit.
Why does my Harley voltage regulator keep burning out?
Recurring regulator failure almost always points to an unresolved upstream condition: a partially shorted stator, chafed stator wires creating an intermittent ground fault, a corroded regulator ground circuit (resistance above 0.5 ohms per the factory spec), or an aftermarket accessory drawing more current than the charging system can supply. Solve the root cause first. The 2013 Dyna Electrical Diagnosis (Section 3.6, Overcharging Diagnostic) specifically lists “open in GND 1 circuit” as a cause of regulator-killing overcharge conditions.
How long does a Harley voltage regulator last?
Most factory regulators on Twin Cam bikes last 40,000-80,000 miles under normal conditions. Heat exposure is the primary life-limiting factor – bikes ridden predominantly in stop-and-go urban traffic see more thermal cycling and typically need earlier replacement. The regulator’s aluminum fins are designed to dissipate heat, but if the bike idles for extended periods with heavy electrical load (lights, heated gear, audio), the regulator runs hotter and ages faster.
What are the Harley voltage regulator OEM part numbers by year?
Touring models: 74505-04 (2004-2005), 74505-06 / 74505-06A (2006-2008), 74505-09 / 74505-09A (2009-2016). Softail models: 74540-08 (2008-2009), 74540-11 (2010-2016). Dyna models use similar Touring-era numbers with slightly different mounting hardware in some years. Always cross-reference your VIN at a Harley dealer or J&P Cycles to confirm the exact OEM PN for your specific model and year.
Our free VIN decoder and recall lookup surfaces the same model-year data alongside any open NHTSA campaigns.
Can a bad voltage regulator damage my Harley’s ECM or BCM?
In severe overcharging failure (sustained above 15V), there is real risk of damaging voltage-sensitive electronics including the ECM, BCM, and any aftermarket accessories. Normal regulator failure – which typically produces gradual symptoms before reaching damaging voltage levels – is less likely to take out the ECM. However, if a regulator has failed catastrophically and the bike was ridden for an extended period in an overcharging condition, we’d recommend having the dealer scan all modules for fault codes before declaring the repair complete.
On EFI models, unstable charging voltage can also cause the fuel pump relay to cycle erratically – our Harley fuel pump symptoms guide explains how to separate a pump fault from a charging system fault.
How do I check if my Harley voltage regulator ground is good?
With the ignition off, disconnect the regulator output connector [77]. Set your multimeter to resistance (ohms) mode. Touch one lead to the ground pin on the regulator connector (marked – or black wire) and the other lead to a known chassis ground point (battery negative terminal or bare frame metal). The reading must be below 0.5 ohms per the HD factory specification. Anything above 0.5 ohms indicates a corroded or loose ground circuit that needs cleaning and re-tightening before any regulator replacement.
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Hello, my name is Frank. I have a 2012 HD Sportster 1200 custom. My bike sat in the garage all winter with a battery tender on. I went to start last week and it cranks but will not start. I had the battery tested by the dealership and it’s good. I changed the battery in the fob, I replaced the relay fuses, I replaced the spark plugs, I dumped the old fuel and put fresh fuel, when I turn on the fuel pump cycles. Still it just cranks but will not start. Any ideas? Please advise. Thanks!
Another possibility is that the carburetor needs to be cleaned. This is a common problem with bikes that sit for a while. You can try spraying some carb cleaner into the carb and see if that helps.
Could this also cause my bike to stall while riding? I’ve been having a problem with my 2002 Harley Sportster 883 where at first it was popping and coughing through the carb then started to back fire then would shut off after. I would wait for a minute or less and all power would come back on. So i bought a new battery for it also ended up buying circuit breaker as well and a new ign. Module and cleaned out my carb. I turned it on ran it for about 30 mins it ran great no more back fire coughing or anything. Then I turned it off let it cool down for about 20 mins and drove it again. This time as I was driving on the freeway it stalled again. But no backfire or cough or anything. Any idea what it could be ?I’m waiting for my new ignition coil but at this point I’m pulling my hair!
Charging system not charging stator check good on my third regulator still won’t charge anything else I can check
I am not sure why when I look at the WEB and ASK ,,,
MY harley electra glide will ONLY spark once or twice after the starter button is released . I can find 20 places where it states the same (((( will ONLY spark once or twice after the starter button is released )))) BUT NOTHING states why ! ! There is talk about the switch , battery low , connections corroded , ALL this is GUESS work .
Everything on the bike was working before it was parked one – or one one half years ago .
Was never touched after parked because now I am a disabled VET . So well I take it out last month and check every thing I can get to . Back in the late 70’s and 80’s I worked for Harley Davidson and things were simple back then .
Well NOTHING about why it will only fire once . ? IF it can fire once then it must get electric from some ware that will go to the coil .
As far as the battery ,, I took out the plugs hooked up my truck battery ( 12.6 just battery ) when I hit the starter it will turn over fine and battery only went down to 12.4 volts with starter spinning . There is still NO spark until after I let the starter button go ,, then some times 1 ( one ) spark .
Does anyone know why ? ? or how to trace that ONE spark that will fire ? .
Thanks
Richard – thanks for the detailed write-up, and for your service. The symptom you’re describing (cranks fine, no spark while the button is held, then 1-2 sparks on release) is unusual but does have a known pattern on older Evo Electra Glides. Three likely causes to investigate, in order of probability:
1. Ignition switch wear (most common after long storage): The switch has separate contacts for the START position versus RUN position. When the contacts oxidize, the bike can hold “in start” mode while the button is pressed (which on some wiring configurations cuts ignition voltage in favor of cranking), then briefly land in RUN as the button releases – giving you that one spark before the switch fully drops out. Worth probing the coil (+) terminal with a multimeter while you cycle the button to see if it loses voltage during crank.
2. Ignition module heat-soak / age failure: Evo ignition modules are notorious for failing after long storage. The module needs a steady trigger signal from the pickup coil to fire continuously; if its internal switching transistor is weak, it might only manage 1-2 firings on power-up.
3. Pickup coil resistance out of spec: A failing pickup can give one strong pulse on first rotation, then nothing. Spec is in the HD service manual for your year.
HDForums has multiple Evo no-spark threads where this exact pattern resolved with either the ignition switch or module swap. If you have a friend with an independent HD shop nearby, an oscilloscope session on the coil primary will pinpoint this in 20 minutes.
– BackyardRider Team
I have a 92 ultra tour glide and the voltage meter once in a while spikes well above normal charging. It spiked approximately 6 times during a 4 hour ride. Does this sound like the regulator to you?
Andy, yes – intermittent over-voltage spikes on a 1992 Evo Touring almost always point to the rectifier-regulator unit, not the stator. Here’s why: a failing stator typically presents as low or no charge (under 13V at the battery with engine running), because it stops producing enough AC current to feed the system. A failing regulator presents as uncontrolled output – the chopping/reference circuit drops out intermittently, and you get spikes well above the normal 14.0-14.8V cruise window.
Two quick tests before you spend money: with the bike running at 2,000 RPM, your DC voltage at the battery should hold steady between 13.8-14.8V. If you see spikes above 15V on your dash gauge, confirm with a multimeter at the battery (gauges can lie). Second, with the bike running, AC voltage at the same terminals should read under 0.5V – anything higher means rectification is failing and the regulator is the prime suspect. Per HDForums Evo charging diagnostic threads, sustained spikes above 15V will cook the battery and eventually take out lights and ignition modules, so this is worth fixing soon.
– BackyardRider Team