HARLEY DAVIDSON · MT21M ECU

HARLEY DAVIDSON Fat Boy MT21M tuning files

HARLEY DAVIDSON Fat Boy on the MT21M: matched, calibrated and delivered with care. Stock output across the matched variants spans 90–94 HP. There are 5 distinct variants on file for this combination. For this platform the dependable path begins with Stage 1 and Stage 2. We match the right calibration to your exact software and validate it before delivery.

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Available solutions

Solutions that apply to the MT21M on this vehicle platform. The exact set depends on the specific engine and software version.

Stage 1 Stage 2

Engine variants & ECU software

5 distinct variants for the HARLEY DAVIDSON Fat Boy on the MT21M ECU. Reference the engine and controller software when you upload.

Variant 1

ECU

Catalog engine: 1895 94HP
Controller brand: DELPHI
ECU: MT21M
Stock power: 94 HP
SW upgrade: 41000850E
Calibration: 41000850E

Variant 2

ECU

Catalog engine: 1868 90HP
Controller brand: DELPHI
ECU: MT21M
Stock power: 90 HP
SW upgrade: 41001147C
Calibration: 41001147C

Variant 3

ECU

Catalog engine: 1868 90HP
Controller brand: DELPHI
ECU: MT21M
Stock power: 90 HP

Variant 4

ECU

Catalog engine: 1868 90HP
Controller brand: DELPHI
ECU: MT21M
Stock power: 90 HP
SW upgrade: 41000883D
Calibration: 41000883D

Variant 5

ECU

Catalog engine: 1868 90HP
Controller brand: DELPHI
ECU: MT21M
Stock power: 90 HP
SW upgrade: 41000980C
Calibration: 41000980C

Related vehicles

Other vehicles built on the MT21M controller or the same engine — handy when a platform spans several models and makes.

Questions, answered.

Which tuning solutions are available for the HARLEY DAVIDSON Fat Boy on the MT21M?

Stage 1, Stage 2. The exact set depends on the specific engine and software version.

Do you cover the MT21M ECU software on this model?

Yes — the HARLEY DAVIDSON Fat Boy on the MT21M ECU is part of the catalog. Upload your original file and it is matched to the right calibration before any work is done.

How is the file delivered?

Through the TuningBay workflow with operator validation and one safe, sensible result per job. Files we deliver, we stand behind.