How to Tell What Kind of Stator Your Motor Has
Whether you're wiring up a CT70, a clone motor, or a full DC system, it’s important to know what kind of stator you're working with. Here's how to identify whether your engine uses a grounded (half-wave) or floating (full-wave) stator using wire color, multimeter testing, and behavior clues.
Grounded Stator
(Half-Wave System)
What It Is:
One leg of the stator coil is grounded to the engine or frame. This setup outputs AC on a single coil with the return path through the engine case. It supports half-wave rectification, meaning only one half of the AC waveform is converted to DC.
How to Identify It:
- Two wires from the stator: typically yellow and white
- Both wires will show continuity to the engine/frame
- Common on many aftermarket kick-start-only motors
- Usually paired with a half-wave regulator/rectifier
System Behavior:
- AC lighting (headlight/taillight) runs on regulated AC
- DC charging (battery, horn, turn signals) runs on rectified DC
- Lighting may dim slightly at low RPM
Floating Ground Stator
(Full-Wave System)
What It Is:
Neither leg of the coil is grounded. Both wires output current and are isolated from the engine/frame. This allows for full-wave rectification, converting both halves of the AC waveform to DC for improved charging efficiency.
How to Identify It:
- Two wires from the stator: typically yellow and yellow, or yellow and pink
- Neither wire shows continuity to the engine/frame
- Common on electric start motors and modern high-output engines
- Must be paired with a full-wave rectifier/regulator
System Behavior:
- Entire system runs on regulated DC
- Stable, bright lighting even at idle
- Fully supports LED lighting, digital gauges, and battery-powered accessories
Quick Testing Guide
-
Wire Color Check:
- Yellow and White → Grounded stator (half-wave)
- Yellow and Yellow or Yellow and Pink → Floating stator (full-wave)
-
Continuity Test:
Use a multimeter in continuity mode and check each stator wire to the engine/frame:- Both wires show continuity → Grounded stator
- No continuity on either wire → Floating stator
-
Regulator/Rectifier Clue:
- Full-wave rectifier uses both stator wires equally for DC conversion. Usually a larger unit.
-
Half-wave rectifier uses one wire for DC conversion, the other is regulated for AC headlight. Usually a smaller unit
Why It Matters
Matching your stator type with the correct regulator/rectifier ensures:
- Proper battery charging
- Stable lighting performance
- Protection against over-voltage
- Compatibility with electric start and DC accessories
Need additional help determining your system? Contact Us!