Cylinder Head Gasket – Fits Yamaha 2 HP (Replaces 6F8-11181-A1, 646-11181-01, 6A1-11181-A0)
Cylinder Head Gasket – Fits Yamaha 2 HP (Replaces 6F8-11181-A1, 646-11181-01, 6A1-11181-A0) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Product Details
This replacement Cylinder Head Gasket – Fits Yamaha 2 HP is designed for 2-stroke outboard engines, specifically the Yamaha 2CMH model from 2003 and newer. It ensures a proper seal between the cylinder head and the engine block, which is critical for maintaining compression and preventing leaks.
It serves as a direct replacement for Yamaha OEM part numbers 6F8-11181-A1, 646-11181-01, and 6A1-11181-A0, as well as aftermarket equivalent GLM34900.
- Engineered for direct-fit installation.
- Designed for use in marine gasoline engines.
- Includes one cylinder head gasket per package.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Yamaha | 6F8-11181-A1 / 6F8-11181-A1-00 | OEM Reference |
| Yamaha | 646-11181-01 / 646-11181-01-00 | OEM Reference |
| Yamaha | 6A1-11181-A0 / 6A1-11181-A0-00 | OEM Reference |
| Aftermarket | GLM34900 | Interchange Part |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | 2CMH | 2 | 2-Stroke | 2003+ | 6F8-11181-A1 | Alternative part numbers: 646-11181-01, 6A1-11181-A0 |
Technical Specs
- Product Type
- Cylinder Head Gasket
- Installation
- Direct replacement
- Fuel Type
- Gasoline
- Dimensions
- 14.0" L x 9.0" W x 0.5" H
What’s in the Box
- 1 x Cylinder Head Gasket (Replaces 6F8-11181-A1/646-11181-01/6A1-11181-A0)
Installation Notes
- Disconnect the spark plug wire to prevent accidental starting.
- Clean the area around the cylinder head to stop debris from falling into the engine.
- Carefully loosen and remove the cylinder head bolts in the reverse sequence recommended by the manufacturer.
- Lift the cylinder head off the engine block. Avoid using tools to pry it off, which can damage the mating surfaces.
- Remove the old gasket. Thoroughly clean all old gasket material, sealant, and carbon from both the engine block and cylinder head surfaces.
- Position the new gasket correctly on the engine block; do not use sealant unless specified by the engine manufacturer.
- Carefully place the cylinder head back onto the block.
- Install and tighten the head bolts in the correct sequence and to the specific torque values listed in your engine's service manual.
Troubleshooting & FAQ
How do I know if my cylinder head gasket is failing?
Common signs of a bad head gasket include loss of compression, engine overheating, white smoke from the exhaust (coolant burning), or milky-looking oil (coolant mixing with oil). A visual inspection may also reveal external oil or coolant leaks around the cylinder head seam.
Will this gasket fit a Yamaha 2 HP model from before 2003?
This gasket is specified for the Yamaha 2CMH model line from 2003 and newer. While it cross-references older part numbers, compatibility with pre-2003 models is not guaranteed. Please verify your exact model and part number before ordering.
What is the correct way to tighten the cylinder head bolts?
Always follow the torque specifications and tightening sequence outlined in your engine’s official service manual. Overtightening, undertightening, or tightening in the wrong order can cause the gasket to fail prematurely.
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.
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.
Payment & Security
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