Piston Kit – Fits Mercury/Mariner 65-125 HP (Replaces 826191T4K)

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Product Details

This is an OEM-quality REC2704-826191T4K piston kit designed for Mercury and Mariner 65–125 HP 2-stroke, 3 & 4 cylinder outboard engines manufactured between 1994 and 2004. It serves as a reliable, direct-fit replacement for the original component, ensuring restored engine performance.

This part directly interchanges with Mercury part numbers 2704-826191T4K and 826191T4, as well as Sierra SIE18-4626 and GLM GLM14470.

Installation: Direct OEM Replacement
Bore Size: Standard (STD)
Application: Gasoline 2-Stroke Outboard Engines

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number
Mercury	2704-826191T4K
Mercury	826191T4
Sierra	SIE18-4626
GLM	GLM14470

Engine & Model Compatibility

Confirm your engine model/year in the table below.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.
Mercury	Jet	65	2-Stroke	1994–1998	826191T4K
Mercury	Jet	80	2-Stroke	1994–1998	826191T4K
Mercury	Outboard	75	2-Stroke	1994–2004	826191T4K
Mercury	Outboard	90	2-Stroke	1994–2004	826191T4K
Mercury	Outboard	100	2-Stroke	1994–2001	826191T4K
Mercury	Outboard	115	2-Stroke	1994–2004	826191T4K
Mercury	Outboard	125	2-Stroke	1994–2004	826191T4K

Technical Specs

Product Type: Piston Kit
Installation: OEM Replacement
Fuel Type: Gasoline
Housing Material: Aluminum Alloy
Housing Color: Silver/Metal
Dimensions: 3.75" x 3.75" x 3.75" (H x W x L)
Other Technical Attributes: Standard Size (STD)

What’s in the Box

1 x Piston Assembly (826191T4K)

Installation Notes

Ensure the engine is off, cool, and disconnected from the battery and fuel supply.
Drain engine oil and coolant.
Carefully remove the cylinder head and old gasket, exposing the pistons.
Rotate the crankshaft to bring the target piston to bottom dead center (BDC) for easier access.
Remove the connecting rod cap and gently push the old piston assembly out of the cylinder.
Lubricate the new piston and rings with fresh 2-stroke engine oil.
Using a ring compressor, carefully slide the new piston assembly into the cylinder, minding the orientation marks.
Re-attach the connecting rod cap and torque the bolts to the manufacturer's specified values.
Reinstall the cylinder head using a new gasket and torque all bolts in the correct sequence.
Refill all fluids, reconnect the battery and fuel line, and check for leaks before starting the engine.

Troubleshooting & FAQ

Will this piston fit my specific 115 HP Mercury engine?

This kit is designed for Mercury 115 HP 2-Stroke outboards made between 1994 and 2004. Always verify your engine's model and year against our compatibility table and check the original part number (826191T4K) to ensure a perfect match.

Is this a standard size or oversized piston?

This is a Standard Size (STD) piston. It is not oversized and is intended for use in cylinder bores that are within OEM specifications and do not require re-boring.

What are the signs of a worn or failing piston?

Common signs of piston failure include a noticeable loss of compression, excessive smoke from the exhaust, a knocking or rattling sound from the engine (piston slap), and the presence of metal shavings in the engine oil during a change.

What is included in the piston kit?

The kit contains the complete piston assembly. This typically includes the piston, piston rings, wrist pin, and circlips required for installation.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.

Shipping speed & cost?

We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns?

Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.

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Safety & Important Info

Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement, not an OEM component.
Professional installation is recommended for safety and performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.

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