This is a heavy duty replacement magneto flywheel rotor, part number RMS120-108136, for the Yamaha YFM 700 Grizzly of 2007 and 2008 and the Yamaha YXR 700 Rhino from 2008 to 2013. The flywheel rotor carries the magnets that sweep past the stator windings and generate the machine's charging current, so it spins with the crankshaft at engine speed for the whole life of the engine, in hot oil, and any magnet that works loose takes the charging system and often the stator with it.
Loose magnets are the known weak point of the original rotor on these 700 cc Yamaha machines. This unit answers that directly: the magnets are bonded with an improved high temperature epoxy and retained by high grade steel capping, so they stay put as the bond is worked by heat and oil. Each rotor is precisely balanced and arrives pre-tested. It measures 118 mm exterior diameter and 107 mm interior diameter, with a centre housing of 38 mm exterior and 23 mm interior diameter, matching the original so it fits the standard crankshaft taper and stator.
Key Features
- Improved high temperature epoxy bonding on the magnets
- High grade steel capping to stop the magnets loosening
- Designed to address the magnet detachment common on original units
- Resists oil degradation of the magnet bond
- Precisely balanced
- Arrives pre-tested
Technical Specs
| Specification |
Detail |
| Part number |
RMS120-108136 |
| Exterior diameter |
118 mm |
| Interior diameter |
107 mm |
| Exterior diameter, centre housing |
38 mm |
| Interior diameter, centre housing |
23 mm |
Vehicle Fitment Guide
| Make & Model |
Years |
| Yamaha YFM 700 Grizzly |
2007-2008 |
| Yamaha YXR 700 Rhino |
2008-2013 |
OEM Part Number Cross Reference
Aftermarket replacement. OEM part numbers are listed for reference only.
| Part Number |
Manufacturer / Brand |
| 3B4-81450-00-00 |
Yamaha |
Frequently Asked Questions
Will it fit without modification?
Yes. The rotor repeats the original dimensions - 118 mm exterior diameter, 107 mm interior diameter and a centre housing of 38 mm exterior and 23 mm interior diameter - so it fits the standard crankshaft and stator with no machining.
What is included?
One improved capped magneto flywheel rotor, balanced and pre-tested. No additional hardware is listed for this part.
How do I know my old rotor has failed?
The usual evidence is a magnet that has come adrift inside the stator cover: a sudden loss of charging, metal debris or magnet fragments in the cover, a grinding or knocking noise from the stator side of the engine, and often a damaged stator alongside it.
Should I replace the stator at the same time?
If a magnet has broken loose it will usually have struck the stator windings, so inspect the stator closely for scoring or damaged insulation before refitting. A rotor fitted against a damaged stator will not restore charging on its own.
Dispatched from the UK · 12-month warranty · Fitment support from our technical team
