A motor bell spins freely but one phase reads open on the multimeter. The enamel burned off a winding after a prop strike stalled the motor at full throttle for three seconds. The motor is “dead” — but the stator, bearings, and bell are fine. A $3 spool of magnet wire and 45 minutes of winding will put it back in the air. Motor rewinding is the most cost-effective repair skill in FPV, and it unlocks custom Kv values that aren’t available off the shelf.
When to Rewind vs Replace
| Condition | Rewind? | Reason |
|---|---|---|
| One phase open (infinite resistance) | Yes | Single broken winding — rewind that phase or all three for consistency |
| Shorted turns (lower than expected resistance) | Yes | Enamel failure between adjacent turns — must fully strip and rewind |
| Burned stator coating (visible darkening) | Maybe | Repaint stator with insulating enamel before rewinding; if lamination insulation is compromised, replace |
| Bent stator (won’t spin true) | No | Mechanical damage to stator lamination stack can’t be fixed by rewinding |
| Worn bearings | No | Rewind doesn’t fix mechanical wear; replace bearings separately |
| Desired Kv not available off-the-shelf | Yes | Fewer turns = higher Kv; more turns = lower Kv |
Rewinding Equipment
- Magnet wire: 0.30mm to 0.50mm (28-24 AWG) for 2207-2508 stators. 0.40mm is the sweet spot for 5-inch motors — thick enough for high copper fill, thin enough to wind without kinking.
- Wire stripper or fine sandpaper (400 grit) for removing enamel from wire ends
- Digital multimeter with continuity mode
- Lighter or soldering iron at 400°C for burning off old enamel/windings
- Small flathead screwdriver or wooden toothpick for packing windings
- Stator insulation enamel (GC Electronics 10-9002 or equivalent)
- Digital caliper for measuring existing wire gauge
- Notepad to record original winding pattern before stripping
Step-by-Step Rewind
Step 1: Document the Original Wind
Before stripping anything, count the turns on each stator tooth. Note the direction (clockwise or counterclockwise) and the termination scheme. Take photos from multiple angles. The most common pattern on 12N14P FPV motors is ABCABCABCABC winding with 6-12 turns per tooth depending on target Kv.
Step 2: Strip the Old Windings
Heat the stator with a lighter or heat gun to soften the enamel and old varnish. Use tweezers to pull out the old wire. If enamel resists, soak the stator in acetone for 2 hours to soften the insulating varnish. Do NOT use a wire brush — it scratches the stator coating and creates paths for inter-lamination shorts.
Step 3: Inspect and Repair Stator Insulation
Under bright light, inspect each stator slot for bare metal exposed through the insulation coating. Any exposed lamination is a potential short point. Apply GC Electronics insulating enamel to any bare spots and let cure for 4 hours. A single short between a winding and the stator creates a phase-to-ground fault that the ESC will detect as a desync condition.
Step 4: Choose Your Target Kv
Kv is inversely proportional to turn count. If the original motor was 2450Kv with 8 turns per tooth:
– 7 turns → 2450 × (8/7) = ~2800Kv
– 9 turns → 2450 × (8/9) = ~2178Kv
– 10 turns → 2450 × (8/10) = ~1960Kv
Wire diameter affects current capacity, not Kv. If you’re reducing turns, use thicker wire to fill the newly available slot space. Higher copper fill = lower phase resistance = less I²R heating.
Step 5: Wind the First Phase
Start with Phase A. Choose a starting tooth and wind clockwise for the specified number of turns. Each “turn” is one complete loop around the tooth. Keep tension firm but not tight enough to stretch the wire — stretched wire reduces cross-sectional area and increases resistance. Pack each turn against the previous one with a toothpick or nylon spudger. No crossing turns — they create hotspots where current density concentrates.
Step 6: Wind Remaining Phases
Follow the ABCABCABCABC pattern: Phase A on teeth 1,4,7,10; Phase B on 2,5,8,11; Phase C on 3,6,9,12. Alternate winding directions between adjacent teeth of the same phase. For LRK winding (fewer terminations but lower copper fill): wind every other tooth and alternate directions.
Step 7: Termination — Wye (Star) or Delta
Wye (Star): Connect the three wire ends together (the “star point”) and use the three start wires as phase outputs. Wye motors produce √3 times more torque per amp at the same Kv but require 1.73× more turns to achieve the same Kv as Delta. Most FPV motors use Wye because it eliminates circulating currents and produces a cleaner back-EMF waveform.
Delta: Connect each phase end to the next phase start in a triangle. The phase junctions become your motor leads. Delta gives you higher Kv with fewer turns, but circulating currents in the delta loop produce additional heating. Only use Delta if you need a Kv higher than Wye can achieve with available slot space.
Step 8: Test Before Final Assembly
Before reassembling the motor:
1. Check resistance between each pair of phase leads — all three should match within 5%
2. Check resistance between each phase lead and the stator — should read open (infinite)
3. Spin the bell by hand and check for scraping — a misaligned winding can contact the magnets
4. Power up with a current-limited supply (1A limit) and spin to moderate RPM — no smoke, no stutter
Copper Fill Comparison
| Wire Gauge (AWG) | Cross-Section (mm²) | Turns/Slot (typical 2306) | Phase Resistance (mΩ) | Max Current (30s) |
|---|---|---|---|---|
| 26 AWG (0.40mm) | 0.129 | 12-14 | 85-110 | 25A |
| 24 AWG (0.51mm) | 0.205 | 8-10 | 55-75 | 35A |
| 23 AWG (0.57mm) | 0.258 | 7-9 | 45-60 | 42A |
| 22 AWG (0.64mm) | 0.326 | 6-8 | 35-50 | 50A |
| Multi-strand (3×28 AWG) | 0.243 | 8-10 | 50-70 | 38A |
What Most Pilots Get Wrong
Mistake 1: Not counting turns before stripping
The consequence: You don’t know the original turn count, so you guess. The rewound motor ends up at 2150Kv instead of 2450Kv because you added an extra turn per tooth. Now you have one motor that runs slower than the other three. The fix: Count three times before stripping. Mark the starting tooth with a permanent marker. If the stator is too burned to identify turns, measure the wire diameter and calculate the maximum turns that fit — that’s almost certainly the original count because manufacturers maximize copper fill.
Mistake 2: Using wire that’s too thick for the slot
The consequence: 0.55mm wire fits the slot with pliers and force, but the enamel is stretched thin at every bend. After 10 flights, a turn-to-turn short develops from vibration abrasion and the phase resistance drops, causing uneven current draw. The fix: The wire should slide into the slot with moderate finger pressure. If you need pliers, drop one gauge size.
Mistake 3: Scraping enamel off the wire ends too aggressively
The consequence: You sand the wire end down to bare copper but also thin the wire’s cross-section at the termination point. This creates a mechanical weak point that fractures under vibration. The fix: Use a lighter to burn off the enamel — it carbonizes at ~250°C and wipes off clean. If sanding, use 400+ grit and stop as soon as you see bright copper.
Mistake 4: Mixing Wye and Delta in the same build
The consequence: Three motors are Wye-terminated from the factory, and your rewound motor is Delta-terminated because you confused the termination scheme. The rewound motor has 1.73× the effective Kv of the others. The quad oscillates violently on arm and the flight controller can’t compensate for the thrust asymmetry. The fix: Confirm the original termination before stripping. Wye motors have four connection points (three phase leads + star point). Delta motors have six connection points that form a triangle. Mark the scheme clearly.
⚠️ Regulatory Notice: Motor modification affects the airworthiness of your unmanned aircraft. In jurisdictions requiring continuing airworthiness documentation (including the FAA under Part 107 operational rules), significant modifications to propulsion components must be documented and may require re-verification of the aircraft’s compliance with its operating limitations. In the EU, EASA’s 2026 Special Condition Light UAS framework requires that modified propulsion systems maintain the original equipment’s safety characteristics. Modified motors used in commercial operations may invalidate manufacturer certifications — verify your operational category requirements before flying modified equipment professionally.
Internal Resources
Motor rewinding pairs with motor maintenance — our FPV motor bearing maintenance guide covers the bearing inspection you should do while the motor is disassembled. For pilots pushing rewound motors hard, our FPV motor timing and demag compensation guide ensures your BLHeli settings don’t cause desyncs on custom-wound motors with different electrical characteristics. Our FPV motor sizing guide helps you decide what Kv target you actually want.
Recommended Video
The motor rewinding tutorial from Electronoobs covers the full process with close-up macro footage of winding technique:
The Magnet Wire That Makes Rewinding Easier
Cheap magnet wire kinks at every bend and the enamel flakes off when you pack turns tight. Temco 200°C magnet wire in 24 AWG has a tougher enamel formulation that survives the abrasion of tight winding without exposing bare copper. One $8 spool rewinds a dozen 2306 stators with enough left over for the next batch of burned motors. If you fly hard enough to kill motors regularly, skip the generic Amazon wire and get the Temco — the enamel quality difference is measurable after the third flight.