CDI Ignition Module for Mercury Optimax 225XS 250XS 300XS

Product Overview

Replacement 5-pin CDI ignition module for selected Mercury Optimax high-performance outboard engines, including 225XS, 225 Sport XS, 250XS, 250 Sport XS, and 300XS applications.

Designed to replace Mercury / Mariner ignition-module references including 300-8M007747, 300-879984T01, 339-879984A1, and 339-879984T00.

This module uses a 5-pin connector and measures approximately 82mm across the main housing and 96mm overall, with a width of approximately 55mm, height of 45mm, and mounting-hole spacing of approximately 75mm.

Before ordering, match the OEM number, connector configuration, mounting dimensions, and original ignition module.

Product Compatibility

Make	Model	Engine Family	OEM Reference
Mercury	Optimax 225XS	Optimax	Verify OEM number
Mercury	225 Sport XS	Optimax / Sport XS	Verify OEM number
Mercury	Optimax 250XS	Optimax	Verify OEM number
Mercury	250 Sport XS	Optimax / Sport XS	Verify OEM number
Mercury	Optimax 300XS	Optimax	Verify OEM number

Because Mercury used different ignition components across engine serial ranges and configurations, model or horsepower alone should not be used to confirm fitment.

OEM Cross-Reference Numbers

Mercury / Mariner

• 300-8M007747
• 300-879984T01
• 339-879984A1
• 339-879984T00

When possible, match one of these references to the original ignition module before ordering.

Specifications

Specification	Details
Product Type	CDI / Ignition Module
Connector	5-Pin
Main Housing Length	Approx. 82 mm / 3.23 in
Overall Length	Approx. 96 mm / 3.78 in
Width	55 mm / 2.17 in
Height	45 mm / 1.77 in
Mounting Hole Distance	75 mm / 2.95 in
Application	Mercury Optimax Outboard
Condition	New
Package Quantity	1 Ignition Module

Key Features

• 5-Pin Configuration: Designed for compatible Mercury Optimax ignition systems using a matching connector.
• Multiple OEM References: Cross-references 300-8M007747, 300-879984T01, 339-879984A1, and 339-879984T00.
• XS Outboard Applications: Intended for selected Mercury 225XS, 250XS, and 300XS engine applications.
• Fitment Reference Dimensions: Approximately 82mm main housing length, 96mm overall length, and 75mm mounting-hole spacing.
• Replacement Ignition Component: Designed as an aftermarket replacement for a failed or damaged compatible original module.