This is a complete brand new kit containing both a generator stator and a Mitsubishi magneto flywheel rotor for the Aprilia RSV4 1000 R Factory and Tuono V4. Supplying the two parts together matters on this engine because the stator and the flywheel work as a matched pair - replacing a failed stator while leaving a tired or demagnetised flywheel in place is one of the most common reasons a rebuilt charging system fails again a short time later.
Both items are direct replacements for the original units and are plug-and-play, so no modification to the loom or the engine cases is required. The stator is wound with the highest grade of copper winding, rated to resist 200 degrees Celsius, on the highest grade of lamination materials. The connector and the rubber grommet are included, and RMSTATOR also supply the opposite connector - the main harness side - because these are frequently found melted, corroded or otherwise defective and are themselves a major cause of repeat electrical faults. Every kit is tested before it is shipped.
Key Features
- Complete kit - generator stator plus Mitsubishi magneto flywheel rotor
- Direct replacement for the original units, plug-and-play fitment
- Highest grade lamination materials and copper winding
- Windings resistant to 200 degrees Celsius
- Connector and rubber grommet included
- Opposite connector (main harness side) also supplied
- Every unit tested before shipping
- Aftermarket replacement for OEM 857201
Technical Specs
| Specification |
Detail |
| Stator interior diameter |
42 mm |
| Stator exterior diameter |
105 mm |
| Stator thickness |
17 mm |
| Wire length (stator to grommet) |
90 mm |
| Wire length (grommet to plug) |
300 mm |
| Number of wires |
3 |
| Number of plugs |
1 |
| Number of pins |
3 |
| Resistance (between each White) |
0.4 ohms +/-20% |
| Winding temperature rating |
200 degrees Celsius |
| Flywheel exterior diameter |
115 mm |
| Flywheel interior diameter |
108 mm |
| Flywheel centre housing interior diameter |
16 mm |
| Flywheel centre housing exterior diameter |
24 mm |
| Flywheel thickness (exterior) |
30 mm |
| Flywheel thickness (interior) |
33 mm |
| Part number |
RMS900-104929 |
Vehicle Fitment Guide
| Make & Model |
Years |
| Aprilia RSV4 1000 R Factory (up to 3413) |
2009-2012 |
| Aprilia Tuono V4 |
2011-2012 |
OEM Part Number Cross Reference
Aftermarket replacement. OEM part numbers are listed for reference only.
| Part Number |
Manufacturer / Brand |
| 857201 (stator) |
Aprilia |
| 857201 (flywheel) |
Aprilia |
Frequently Asked Questions
Does this kit need any modification to fit?
No. Both the stator and the flywheel are direct replacements for the original units and fit plug-and-play, so no cutting, splicing or machining is required.
What is included in the box?
A brand new aftermarket generator stator with its connector and rubber grommet, a brand new Mitsubishi magneto flywheel rotor, and the opposite connector for the main harness side.
How can I tell whether my stator has failed?
Measure the resistance between each of the three White wires with the engine off and the plug disconnected. This unit reads 0.4 ohms +/-20% between each pair. A reading that is open circuit, close to zero, or shorted to the engine case points to a failed winding. A battery that will not hold charge on a bike that is otherwise running normally is the usual symptom.
Why is the flywheel supplied with the stator rather than on its own?
The stator and the flywheel form the charging system together. If the flywheel magnets have weakened, a new stator will not restore full output and will be working under the same conditions that destroyed the original. Fitting both at once returns the system to a known state.
Dispatched from the UK · 12-month warranty · Fitment support from our technical team
