MOSFET Regulator Rectifier for Harley Davidson Roadster XLS 1978-1981
MOSFET Regulator Rectifier for Harley Davidson Roadster XLS 1978-1981
SKU:RMS020-102664
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Mosfet Voltage Regulator - RMS020-102664
Harley Davidson Roadster XLS and Sportster 1000 - 1978-1981
A brand new MOSFET voltage rectifier regulator for the 1978-1981 Harley Davidson Roadster XLS and Sportster 1000, supplied as a direct replacement for the original unit. MOSFET switching runs cooler than OEM diode-style regulators and the unit includes overheat protection, so instead of burning out it shuts down briefly, cools off and carries on working.
Because it regulates by switching the stator coils rather than converting surplus output into heat, the unit reduces load on the stator. The stated benefits are cooler running, improved fuel efficiency, steady regulated energy delivery, longer battery life, enhanced engine power and optimised power delivery. Installation is plug-and-play with an improved heat sink and higher grade electrical components exceeding OEM standards, and every unit is tested before shipping.
Key Features
- MOSFET technology - operates cooler than OEM diode style regulators
- Overheat protection built in
- Direct replacement, plug-and-play installation
- Improved heat sink and charging capability
- Higher grade electrical components, quality exceeding OEM standards
- Lower stator load for improved fuel efficiency and battery life
- Optimised power delivery through stator coil switching
- All products tested before shipment
Technical Specs
| Specification | Detail |
|---|---|
| Width | 68 mm |
| Length | 98 mm |
| Height | 35 mm |
| Fixation holes (centre to centre) | 82 mm |
| Wire length | 210 mm |
| Number of plugs | 1 |
| Number of pins | 3 |
| Number of wires | 3 |
| Minimum charging voltage | 14.5 V +/- 0.5 V |
| Maximum charging current | 50 A / 500 W |
| Open circuit voltage | Less than 15 V |
| Operating temperature | -20 to 85 degrees Celsius |
Vehicle Fitment Guide
| Make & Model | Years |
|---|---|
| Harley Davidson Roadster XLS | 1978-1981 |
| Harley Davidson Sportster 1000 | 1978-1981 |
OEM Part Number Cross Reference
Aftermarket replacement. OEM part numbers are listed for reference only.
| Part Number | Manufacturer / Brand |
|---|---|
| 74504-78 | Harley Davidson |
| H0478 | Cross reference |
Frequently Asked Questions
Does this regulator need modification to fit?
No. It is a plug-and-play direct replacement, with 3 wires on a single 3-pin plug and 82 mm mounting hole spacing matching the original unit.
What is included?
The MOSFET voltage regulator rectifier unit with its 210 mm lead and connector, ready to fit.
How can I tell whether my old regulator has failed?
Fully charge the battery, then measure across its terminals with the engine running. A working charging system holds about 14.5 V plus or minus 0.5 V. A reading that stays at resting battery voltage, or one that rises well beyond 15 V and starts boiling the battery, points to a failed regulator rectifier.
Why choose MOSFET over the original diode type?
Diode regulators burn off excess output as heat, which is what eventually destroys them. This MOSFET unit switches the stator coils instead, so it runs cooler, puts less load on the stator, and will shut down temporarily under overheat rather than failing permanently.
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