M8‑FXR Conversion Guide

M8‑FXR Conversion Guide

The FXR chassis is legendary for its handling and geometry and when paired with the Milwaukee‑Eight (M8) engine, it becomes a modern powerhouse. This guide covers all essential components needed for a clean M8‑FXR build, including drivetrain alignment, fabrication parts, EFI/ECM options, fuel system solutions, and chassis controls.

1. Start With the Foundation: M8‑FXR Swap Kit

The Kleen Moto × Ramjet Racing M8‑FXR Swap Kit contains the core structural components needed to properly mount an M8 Touring drivetrain into the FXR chassis. This kit eliminates guesswork and ensures precise geometry throughout the conversion.

What’s Included

  • M8‑FXR front motor mounts & pivot block covers
  • Softail weld‑on oil cooler mount & tab, upper engine mount bung
  • Universal regulator bracket, frame tie‑in, wiring trim rings
  • Main center Dyna crossmember & removable rear crossmember (with chrome hardware)
  • Wrap‑around rear crossmember tubing with two gussets
  • Two Dyna foot control mounts & extra‑strong kickstand lock/stop
  • Backbone filler plates, motor‑mount filler plates, oil‑bag filler plate

Fitment: Requires an M8 Touring drivetrain (Softail M8 engines do not fit).

2. Dial In Geometry: M8‑FXR Drivetrain Mockup Kit

The Kleen Moto M8‑FXR Drivetrain Mockup Kit allows builders to lock the drivetrain solidly in place during mockup without the flex of rubber isolators or the need to install the swingarm.

What’s Included

  • 3D‑printed swingarm replicator blocks that mimic mount spacing for accurate alignment
  • 3D‑printed Solid mockup isolators to eliminate movement and hold the drivetrain square 

Built for Builders

  • Perfect for M8‑FXR swap mockup
  • Prevents distortion of real rubber isolators
  • Protects expensive OEM parts from unnecessary wear

Mockup‑Only Notice

Not for riding — replace with proper service parts before assembly.

3. Fuel System Upgrade: Flush‑Mount Fuel Pump Flange

For clean EFI tank integration, the Speed Junkie Cycle Works Flush‑Mount Fuel Pump Flange provides a weld‑ready, low‑profile mounting platform for Harley fuel pump #75305‑07A.

  • CNC‑machined steel for maximum strength and weldability
  • Accepts OEM Harley fuel pump #75305‑07A
  • 1/4″‑thick flange for consistent weld surface
  • Six #10‑32 threaded holes (hardware not included)

4. Mid‑Controls: V‑Twin MFG Dyna Mid Control Mounts

These chrome OEM‑style driver footpeg supports are perfect for M8-FXR swaps using Dyna‑based mid‑control setups. 

  • Includes left & right chrome footpeg support brackets
  • Ideal for clean mid‑control conversions or replacing worn mounts
  • Fits 1991–2017 Harley‑Davidson Dyna models

5. Kickstand Options: Drag Specialties Dyna Kickstand

When modifying frame height or stance, the Drag Specialties Dyna Kickstand ensures proper lean angle and stability.

  • Available in chrome or gloss black
  • Standard 11″ and extended 12″ (+1″) lengths
  • Direct OEM replacement (#47904‑90 series)
  • Fits 1991–2017 Dyna models

6. Engine Management Option: NAMZ Stand‑Alone M8 EFI System

The NAMZ N‑EFI‑02 Stand‑Alone M8 EFI Engine Management System is ideal for custom‑frame builds (like FXRs) that aren’t running a BCM. It provides a complete plug‑n‑play harness, ThunderMax ECM, and TBW integration.

Key Features

  • Plug‑n‑play EFI harness designed for M8 engines
  • Proprietary NAMZ twist‑grip sensor operating like OEM TBW
  • Includes ThunderMax ECM for robust tuning
  • Made in the USA for reliability

What It Does

  • Provides full stand‑alone EFI engine control without using the BCM
  • Simplifies wiring on stripped‑down or race‑style builds

Limitations

  • Does not control lighting, gauges, switches, horn, etc.
  • No cruise control support
  • Intended for race use only where emissions laws apply

Requirements

  • M8 throttle body #27300122 or equivalent
  • Big Twin or XL fuel pump
  • Aftermarket speedometer/fuel readout (Softail ’05‑10, Dyna ’05‑11, Touring/XL ’05‑13)
  • Ignition coil HD#31600017 & speed sensor HD#74402‑05B

7. Preferred Engine Management: OEM Harley‑Davidson ECM + BCM

Although the NAMZ stand‑alone system is excellent for BCM‑free custom builds, our preferred approach for most M8‑FXR conversions is to use the OEM Harley‑Davidson ECM + BCM. This provides full factory‑style integration for engine management, lighting, gauges, safety systems, and diagnostics.

Why We Prefer OEM ECM/BCM

  • Controls engine, lighting, gauges, switches, safety systems — everything in one ecosystem
  • OEM‑grade reliability and diagnostic support
  • Best choice for riders wanting full functionality and OE‑style behavior

Considerations

  • Requires CAN‑bus compatible harness routing
  • Requires module mounting solutions inside FXR chassis
  • Security module or fob integration may be required

OEM vs Stand‑Alone

  • OEM ECM/BCM: best for complete motorcycles with full functionality
  • NAMZ Stand‑Alone: best for stripped‑down customs, minimalist builds, and race setups where only engine management is needed

8. Recommended M8‑FXR Build Workflow

  1. Mockup drivetrain using isolators/replicators
  2. Install swap‑kit structural components & tack weld
  3. Install/weld fuel pump flange and verify pump orientation
  4. Select and wire engine management (OEM or NAMZ)
  5. Install mid controls and linkage
  6. Fit proper kickstand for stance correction
  7. Final weld, coat, assemble, and tune

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