Compufire 40A 3 Phase Charging System - 40 AMP NON Vented `1981-1999 BT/EVO — Harley-Davidson (1981-1999)

Compufire 40A 3-phase charging system for Big Twin and EVO Harley engines, delivering 25 amps at idle and 40 amps above 2800 rpm. Made in the USA with a vented rotor for heat dissipation and high-output voltage regulator set to 14.25V from idle.

Features

• 40 AMP output above 2800 rpm
• 25 AMP output at idle
• Vented rotor for heat dissipation
• High-output voltage regulator (14.25V from idle)
• Made in the USA
• Compatible with OEM primary due to narrow rotor and stator profile

Specifications

• Brand: Compufire
• Manufacturer Part #: 55570
• UPC: 694342548087
• Output: 25A idle / 40A above 2800 rpm
• Voltage Regulator: 14.25V from idle
• Length: 9 in
• Width: 8 in
• Height: 8 in
• Weight: 11 lbs

Fitment

Fits 1981-1999 Harley Big Twin and EVO engines in Softail, Dyna, and FLT models with OEM primary.

Frequently Asked Questions

Will this fit my 1981-1999 Harley Softail, Dyna, or FLT?

Yes — this system is designed for those chassis with OEM primary cases. The narrow rotor and stator profile ensure fitment without modifications.

What's the output at idle versus cruising speed?

This system produces 25 amps at idle and builds to 40 amps once you exceed 2800 rpm, keeping your battery charged in all conditions.

Does the vented rotor help with reliability?

Yes — the vented rotor design improves heat dissipation, keeping the stator cooler and allowing the system to sustain maximum output longer.

Is this system made overseas?

No — Compufire manufactures this 40A system in the USA.