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Alternator BMW K75 K100 K1100 R850 R1100 R1150 GS RT RS 12V 50A 12312306020

Alternator BMW K75 K100 K1100 R850 R1100 R1150 GS RT RS 12V 50A 12312306020

SKU:400-24131

Regular price £230.00 GBP
Regular price £380.88 GBP Sale price £230.00 GBP
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BMW Motorcycle Alternator

Fits K75, K100, K1100 & Oilhead Boxers (50 Amp)

Keep your classic BMW touring machine powered with this high-quality replacement **50 Amp Alternator**. Designed for the legendary "Flying Brick" **K-Series (K75, K100, K1100)** and the robust "Oilhead" **R-Series (R850, R1100, R1150)**, this unit ensures reliable charging for your heated grips, lights, and ABS systems.

This **Bosch Style** alternator is a direct bolt-on replacement. It comes complete with a **4-groove serpentine pulley**, matching the factory drive belt system perfectly.

COMPLETE UNIT: Includes the internal voltage regulator and 4-rib pulley, ready to install out of the box.

Key Features

  • Direct Fit: Replaces Bosch 0123105001.
  • High Output: 50 Amps for touring accessories.
  • Cooling: Efficient Internal Fan (IF) design.
  • Pulley Included: 4-Groove Poly-V.

Technical Specs

Voltage: 12 Volts
Amperage: 50 Amps
Rotation: CW (Clockwise)
Pulley: 4-Groove Serpentine
Regulator: Internal (IR)
SKU Reference: 400-24131

Vehicle Fitment Guide

Series Models Year Range
BMW K-Series K75 (C, S, RT) 1986 - 1996
BMW K-Series K100 / K1 (LT, RS, RT) 1984 - 1993
BMW K-Series K1100 (LT, RS) 1993 - 1999
BMW R-Series R850 / R1100 (GS, R, RS, RT) 1993 - 2001
BMW R-Series R1150 / R1200C (GS, RT) 1999 - 2006

Part Number Cross Reference

BMW 12-31-2-306-020, 12-31-1-342-767, 12312306020
Bosch 0-123-105-001, 0-123-105-002, 0123105001
Arrowhead ABO0364
Lester 12494

Frequently Asked Questions

Will this fit my 1988 K75S?

Yes, this 50A alternator is the standard replacement for all K75 models from 1986-1996.

Can I upgrade from my 33A alternator?

Yes, older K-bikes often came with 33A units. This 50A alternator is a popular plug-and-play upgrade to provide more power for accessories like heated gear.

Does it include the rubber dampers?

No, this listing is for the alternator unit itself. We highly recommend inspecting and replacing the rubber drive dampers (monkey nuts) in the engine cup when installing this new unit.

Note: Please verify your existing alternator mounting and pulley type.
Fast shipping available across the UK and Europe.

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Shipping calculated at checkout. Free shipping over £150. Terms apply