1SL-12121-00 Yamaha Exhaust Valve | Genuine OEM Yamaha Outboard Part

🔧 Product Description

Genuine Yamaha Exhaust Valve - Part Number: 1SL-12121-00-00

A genuine Yamaha exhaust valve used in Yamaha four-stroke cylinder head valve train assemblies where OEM part number 1SL-12121-00-00 is specified. This valve controls exhaust gas flow from the combustion chamber and is a critical sealing component for compression, combustion efficiency and engine performance.

⚙️ Key Features

• Genuine Yamaha OEM exhaust valve
• Correct Yamaha part number 1SL-12121-00-00
• Exhaust-side cylinder head valve component
• Designed for Yamaha four-stroke engine valve train assemblies
• Precision valve face and stem design for correct sealing and heat transfer

🚤 Compatibility

Commonly used on

• Yamaha four-stroke cylinder head valve train assemblies
• Yamaha exhaust valve applications where 1SL-12121-00-00 is specified by the parts diagram

Typically suits

• Engine models:
• Yamaha YZ450F four-stroke valve applications where 1SL-12121-00-00 is specified
• Yamaha WR450F four-stroke valve applications where 1SL-12121-00-00 is specified
• Yamaha 450cc four-stroke cylinder head assemblies using the 1SL exhaust valve family
• Yamaha engine applications requiring OEM exhaust valve 1SL-12121-00-00
• Engine Type: Yamaha four-stroke engine
• Valve Type: Exhaust valve
• Year Range: model-specific Yamaha 1SL-series valve applications
• Fitment Note: Match by OEM part number and engine parts diagram before installation

🔌 Function

The exhaust valve opens during the exhaust stroke to allow burnt gases to exit the combustion chamber, then closes to seal the cylinder during compression and combustion.

⚠️ Common Signs of Failure

• Low compression
• Hard starting
• Poor idle quality
• Misfire or loss of power
• Excessive exhaust leakage
• Burnt, pitted or warped valve face
• Valve clearance repeatedly going out of specification

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 1SL-12121-00-00 Yamaha exhaust valve reference
• 1SL-12121-00 short Yamaha exhaust valve format

OEM / Related Numbers

• 1SL-12121-00-00
• 1SL-12121-00
• 1SL121210000
• 1SL1212100

Aftermarket / Verified Equivalents

• ProX: 28.2444-1
• ProX titanium exhaust valve replacement family
• Aftermarket reference: 1SL-12121-00
• Aftermarket reference: 1SL1212100
• Yamaha 450 four-stroke exhaust valve replacement family where this OEM number is specified

📦 Condition

• Genuine Yamaha part
• Brand new
• Supplied in original or equivalent packaging