4HP / 5HP Mariner Outboard Base Gasket – JAPAN Models Only (2-Stroke)

Replaces 27-91780 / 91780M – Yamaha-Built Mariner – UK Stock

Product Description

Base gasket for Mariner 4HP and 5HP 2-stroke outboards, Japan-built models made by Yamaha. These engines have serial numbers starting with 6E0 or 6E3 and share many parts with Yamaha’s 4A and 5C series.

This gasket fits between the powerhead and the midsection to properly seal the lower end of the engine. High-quality aftermarket part with OEM-style fit.

Fitment

Mariner 4HP / 5HP
2-Stroke
Japan models only
Serial number starts with 6E0 or 6E3
Based on Yamaha 4A / 5C design

Will NOT fit Mariner engines made by Mercury USA or Belgium.

Replaces Mariner Part Numbers

27-91780
27-91780M
91780
91780M

Why Buy from SSI MARINE?

All parts are stocked in the UK
Selected by marine technicians for fit and quality
Same-day dispatch before 1 PM (Mon–Fri)
Collection available from our Leigh (Manchester) workshop

If you're unsure about compatibility, contact us with your serial number and we’ll confirm the fit.

Shipping & Collection

Tracked 24-hour UK delivery
Same-day dispatch before 1 PM
In-person collection available Monday to Friday