6H1-45300-23 EK Yamaha 25" Extra Long Shaft Gearbox | Genuine Used Part

🔧 Product Description

Genuine Yamaha Extra-Long Lower Unit - Part Number: 6H1-45300-23-EK

A genuine used Yamaha 6H1-family complete lower unit identified as an approximately 25-inch extra-long gearcase for selected 75HP to 90HP two-stroke outboards. Yamaha 6H1-45300-23-EK supersedes earlier 20, 21 and 22-EK assemblies. Later catalogues may show 6H1-45300-27-8D for certain 25-inch 80HP and 90HP engines, so driveshaft length must be physically confirmed.

⚙️ Key Features

• Genuine Yamaha complete lower-unit assembly
• Correct service reference 6H1-45300-23-EK
• Early export-market 6H1 gearcase family
• Intended for extra-long-shaft applications when measured as 25 inches
• Used on selected 75HP to 90HP two-stroke engines

🚤 Compatibility

Commonly used on

• Yamaha 75HP, 80HP, 85HP and 90HP two-stroke engines
• Early-1990s export and international extra-long-shaft installations
• Standard right-hand propeller rotation unless identified otherwise

Typically suits

• Yamaha 90A and related 1991-1995 export models
• Selected 75A, 80A and 85A engines using the same 6H1 gearcase family
• Later 80AETO and 90AET engines may specify 6H1-45300-27-8D instead
• The installed shaft length must be measured before listing as 25-inch
• HP Range: Approximately 75HP - 90HP
• Shaft Length: Approximately 25 inches when verified
• Gear Ratio: Commonly 2.00:1; confirm gear teeth
• Rotation: Standard right-hand
• Fitment Requirement: Measure driveshaft and shift shaft and confirm the complete model diagram

🔌 Function

The assembly transfers power to the propeller, provides forward and reverse gearing and houses the water pump that supplies cooling water to the engine.

⚠️ Common Signs of Failure

• Incorrect shaft length for the midsection
• Water-contaminated gear oil
• Gear-clutch wear or jumping out of gear
• Propeller-shaft runout
• Corrosion or cracking around the bearing carrier

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 6H1-45300-23-EK supersedes 6H1-45300-22-EK
• Also supersedes 6H1-45300-21-EK and 6H1-45300-20-EK
• 6H1-45300-27-8D is a related later 25-inch service assembly on selected models, not a universal direct supersession

OEM / Related Numbers

• 6H1-45300-23-EK
• 6H14530023EK
• 6H1-45300-22-EK
• 6H1-45300-21-EK
• 6H1-45300-20-EK
• 6H1-45300-27-8D related X-shaft assembly
• 6H1-W0001-series seal kit

Aftermarket / Verified Equivalents

• SEI Marine SE404-family 25-inch replacement where the ratio, shift direction and spline count match
• Remanufactured Yamaha 75HP-90HP extra-long lower units
• Aftermarket 6H1 gear sets, seals and bearings
• Sierra and Recmar water-pump service kits
• Used genuine later 6H1 25-inch units after dimensional verification

📦 Condition

• Genuine used part
• Removed from running engine or vessel where applicable
• In good working condition unless otherwise stated