Harddrive Regulator - BIG Twin BLK `1981-1988 OEM 74516-86 — Harley-Davidson Softail Heritage Classic, Softail Fat Boy, Electra Glide (1955-2026)

Harddrive regulator for Big Twin V-twin engines, 1981–1988 models. Built to OEM 74516-86 specifications with sealed high-temperature encapsulation and SCR (Silicon Controlled Rectifier) technology for cooler, more efficient charging system operation.

Features

• Meets/exceeds OEM specifications
• Silicon Controlled Rectifier (SCR) technology for cooler operation
• Sealed high-temperature encapsulation
• Surface-mount circuit board design minimizes thermal impedance
• OEM-grade high-temperature wiring harness

Specifications

• Brand: Harddrive
• Manufacturer Part #: H1686
• OEM Part Reference: 74516-86
• UPC: 191361170041
• Length: 5.2 in
• Width: 5.1 in
• Height: 3.3 in
• Weight: 0.85 lbs
• Country of Origin: China (Mainland)

Fitment

Fits Harley-Davidson Big Twin V-twin models, 1981–1988 model years with OEM charging systems.

Frequently Asked Questions

What is the OEM equivalent part number?

This Harddrive regulator meets OEM Harley-Davidson part number 74516-86 specifications.

Will this fit my 1979 Big Twin?

This part is for 1981–1988 Big Twin models. Older 1979–1980 Harleys use a different regulator design.

Why does this regulator run cooler than stock?

The SCR (Silicon Controlled Rectifier) circuit and sealed surface-mount board design conducts heat more efficiently, reducing thermal strain on the charging system.

Is this a direct bolt-on replacement?

Yes — it uses the OEM-grade wiring harness and mounts in place of the original regulator with no modifications required.