This is a brand new aftermarket voltage regulator rectifier, supplied as a direct replacement for the original unit on Kawasaki STX-R 1200 and Ultra 150 watercraft. It is plug-and-play and a direct fit, so installation is easy and no assembly is required. The quality exceeds the OEM equipment, with an improved heat sink, improved charging capability and a higher grade of electric components throughout. Every unit is tested before it is shipped.
One detail sets this package apart. Corrosion in the harness-side connector is a common problem on these machines, so the opposite connector - the main harness side - is supplied with the regulator. That means you can renew both halves of the connection at the same time instead of fitting a new regulator onto a corroded plug and inviting the same fault back. The unit delivers a minimum charging voltage of 14.5 V +/- 0.5 V with a maximum charging current of 25 A / 300 W.
Key Features
- Brand new aftermarket voltage regulator rectifier
- Direct replacement to your original unit
- Plug-and-play, direct fit, easy installation
- No assembly required
- Supplied with the opposite connector for the main harness side, addressing common corrosion issues
- Improved heat sink and charging capabilities
- Higher grade of electric components
- The quality exceeds the OEM equipment
- All units are tested before shipment
Technical Specs
| Specification |
Detail |
| Part number |
RM30904 |
| Width |
65 mm |
| Length |
76 mm |
| Height |
26 mm |
| Fixation holes centre to centre |
55 mm |
| Number of plugs |
1 |
| Number of pins |
6 |
| Minimum charging voltage |
14.5 V +/- 0.5 V |
| Maximum charging current |
25 A / 300 W |
| Open circuit voltage |
Less than 15 V |
| Operating temperature |
-20 C to 85 C |
Vehicle Fitment Guide
Years shown are the overall coverage span for this part. Please confirm against the OEM part number on your original unit before ordering.
| Make & Model |
Years |
| Kawasaki STX-R 1200 |
1999-2005 |
| Kawasaki Ultra 150 |
1999-2005 |
OEM Part Number Cross Reference
Aftermarket replacement. OEM part numbers are listed for reference only.
| Part Number |
Manufacturer / Brand |
| 21066-3716 |
Kawasaki |
| 21066-3715 |
Kawasaki |
Frequently Asked Questions
Does this need any modification to fit?
No. It is plug-and-play and a direct fit with no assembly required. It uses a single 6-pin plug and the fixation holes are 55 mm centre to centre, matching the original mounting.
What is included in the box?
You receive the voltage regulator rectifier itself plus the opposite connector for the main harness side. That second connector is included specifically because corrosion in the harness-side plug is a common failure point on these machines.
How do I know my old regulator has failed?
With the engine running, the charging system should hold at least 14.5 V +/- 0.5 V at the battery. If voltage stays flat at battery level, or rises past 15 V and boils the battery, the regulator rectifier is the usual cause. Check the harness connector at the same time, as a burnt or green-corroded plug will destroy a new unit.
How much charging current will it handle?
Up to 25 A / 300 W maximum charging current, with an open circuit voltage below 15 V, and it is rated for operation between -20 C and 85 C.
Dispatched from the UK · 12-month warranty · Fitment support from our technical team
