CDI UNIT

CDI Unit / Ignition Module for Yamaha F9.9B Outboards

High-quality marine-grade aftermarket CDI ignition unit for selected Yamaha F9.9B 9.9 HP 4-stroke outboard engines.

Designed specifically for the earlier Yamaha F9.9B engine family identified by the 6G9 model/prefix.

FOR 6G9 ENGINES ONLY

Designed as a replacement for Yamaha CDI references including:

6G9-85540-20 / 21 / 22 / 29

Fits Selected Yamaha Outboards

9.9 HP

Yamaha F9.9B

9.9 HP
4 Stroke
Selected F9.9B applications
6G9 engine family / prefix only

⚠️ VERY IMPORTANT

This CDI should NOT be selected simply because your Yamaha outboard is an F9.9 or 9.9 HP 4-stroke.

Yamaha produced several generations of F9.9 outboards using different CDI / ignition components.

Replaces Yamaha Part Numbers

6G9-85540-20
6G9-85540-20-00
6G9-85540-21
6G9-85540-21-00
6G9-85540-22
6G9-85540-22-00
6G9-85540-29
6G9-85540-29-00

Searchable Without Hyphens

6G98554020
6G9855402000
6G98554021
6G9855402100
6G98554022
6G9855402200
6G98554029
6G9855402900

OEM manufacturer names and part numbers are provided for identification and compatibility reference only.

⚠️ 6G9 ENGINE FAMILY ONLY

PLEASE CHECK BEFORE ORDERING

This listing is specifically for selected Yamaha F9.9B engines from the 6G9 family.

Look for:

6G9

in your engine identification / model information and compare the original CDI part number.

Do NOT order this CDI for a different F9.9 engine generation simply because:

Your engine is Yamaha
Your engine is 9.9 HP
Your engine is 4 Stroke
Your engine is marked F9.9
The CDI looks similar

The exact engine family and CDI reference must be checked.

Different Yamaha F9.9 Generations

Yamaha has produced several different 9.9 HP 4-stroke engine families.

For example:

This Listing

F9.9B – 6G9 Family

CDI references:

6G9-85540-20 / 21 / 22 / 29

Other F9.9 Models

Later or different F9.9 engine families can use completely different CDI / ignition-control modules.

These parts are NOT interchangeable simply because the horsepower is the same.

What Is the CDI Unit?

The CDI – Capacitor Discharge Ignition – unit is an important component of the outboard's ignition system.

It controls the ignition operation required for the engine to produce spark at the correct time.

A faulty CDI unit can be associated with symptoms such as:

No spark
Intermittent spark
Difficult starting
Misfiring
Engine cutting out
Loss of ignition when hot
Irregular engine operation

Important

These symptoms do NOT automatically mean that the CDI is faulty.

Similar symptoms can be caused by other ignition or electrical components.

Proper diagnosis is recommended before replacing the CDI unit.

Product Features

Marine-grade aftermarket CDI unit
Ignition control module
Suitable for selected Yamaha outboards
9.9 HP
F9.9B
4 Stroke
6G9 engine family
Replacement for 6G9-85540-20
Replacement for 6G9-85540-21
Replacement for 6G9-85540-22
Replacement for 6G9-85540-29
Direct replacement for compatible applications
No assembly required
New aftermarket ignition component

⚠️ IMPORTANT – Check the Original CDI Number

For the safest identification, compare the part number on your original CDI.

It should correspond with one of the following:

6G9-85540-20

6G9-85540-21

6G9-85540-22

6G9-85540-29

If your original CDI carries a completely different Yamaha prefix, please contact us before ordering.

⚠️ Appearance Does Not Confirm Fitment

If the CDI unit looks the same as the one fitted to your engine, this does not always mean it is the correct part for your outboard.

Different Yamaha CDI units can look very similar externally while having different:

Internal specifications
Ignition characteristics
Wiring
Electrical connectors
Applications

Always check the engine identification and original part number.

Before Replacing Your CDI Unit

If your Yamaha has an ignition fault, we recommend checking the complete ignition system before installing a replacement CDI.

Check:

Ignition coils
Spark plugs
Spark plug caps and leads
Source / charging coil
Pulser / trigger components
Stop / kill circuit
Engine earth / ground connections
CDI wiring
Electrical connectors
Burnt or corroded terminals
Damaged wiring

A fault elsewhere in the ignition system can produce symptoms similar to a failed CDI unit.

Aftermarket Replacement Part

This is a high-quality marine-grade aftermarket replacement part.

It is not a genuine Yamaha component.

Yamaha names and OEM part numbers are provided for identification and compatibility reference only.

The component is designed as a replacement for compatible Yamaha F9.9B 6G9-family applications using the CDI references listed above.

What's Included

1 × CDI Unit / Ignition Module

New aftermarket replacement component.

Buyer Responsibility

It is the buyer's responsibility to confirm compatibility before purchasing.

Please check:

Yamaha engine
9.9 HP
F9.9B
4 Stroke
6G9 engine family / prefix
Exact model information
Original CDI part number
Electrical connections

If you are unsure, please send SSI Marine:

A picture of the engine identification plate + a clear picture of the existing CDI and its part number

Our technical team will be happy to help identify the correct ignition unit.

Why Buy From SSI Marine?

Marine-grade aftermarket & OEM-spec parts
Workshop-tested products
More than 10 years supplying and working with outboard engines
Same-day dispatch before 1 PM Monday–Friday
Royal Mail Tracked 24
UK stock
Collection available from Leigh, Greater Manchester
Technical support from experienced outboard specialists
Workshop open Monday–Friday, 9 AM–5 PM

9.9 HP Yamaha Outboard F9.9B 4 Stroke CDI Unit 6G9 Models 6G9-85540-29