Yamaha 1989-96 25 HP Outboard Specs & Maintenance
Known for its bulletproof reliability, the 1989-1996 25 HP 2-stroke outboard is a favorite among DIY marine mechanics and fishing enthusiasts. Featuring a compact 2-cylinder, 395cc displacement design, this lightweight engine delivers impressive power-to-weight performance for small skiffs and Jon boats. Whether you’re restoring a classic or keeping a reliable workhorse running smoothly, our comprehensive database provides the technical specs, maintenance guides, and parts diagrams you need to keep your motor firing on both cylinders.
Complete Technical Specifications
| Specification | Details |
|---|---|
| Model / Horsepower | 25 |
| Year Range | 1989-96 |
| Engine Type | IL 2-stroke |
| Cylinders | 2 |
| Displacement | 24 cu-in (395 cc) |
| Bore x Stroke | 2.64 x 2.20 in (67 x 56 mm) |
| Compression Ratio | 7.0:1 |
| Full Throttle RPM | 5000-6000 |
| Idle Speed (Neutral) RPM | 700-800 |
| Idle Speed (Trolling) RPM | 600-700 |
| Spark Plug (NGK) | B7HS-10 |
| Spark Plug (Champion) | L82C |
| Spark Plug Gap | 0.035-0.039 in (0.9-1.0 mm) |
| Ignition System | CDI |
| Ignition Timing (Idle) | 6-8 ATDC |
| Ignition Timing (Carb Pickup) | 0-1 ATDC |
| Ignition Timing (Full Advance) | 24-26 |
| Fuel System | Carb |
| Starting System | Man or Man & Elec |
| Oil Injection System | PB or 100:1 PM |
| Injection Oil Ratio | |
| Gear Oil Capacity (mL/cc) | |
| Gear Oil Capacity (Oz) | |
| Approximate Weight | 106-115 lbs (48-52 kg) |
| Battery CCA / Reserve | 210 (40) |
| Battery Reserve | 59 minutes |
| Tach Pole Setting | 4 |
| Test Propeller Part Number | YB-1621 |
| Test Propeller New Engine RPM | 4200-4400 |
Maintenance Summary
Routine maintenance keeps this 24 cu. in. 2-stroke running strong. Always gap NGK B7HS-10 spark plugs to 0.035–0.039 inches (0.9–1.0 mm). For optimal performance, regularly inspect the water pump impeller, mix fresh fuel carefully, and service lower unit gear lube before each season.
Disclaimer & Information Notice: Specifications, fuel ratios, and maintenance guidelines listed on VintageMotorSpecs.com are compiled for historical reference and educational purposes only. Always verify data against an official OEM service manual prior to ordering parts or executing repairs. VintageMotorSpecs.com assumes no liability for repair errors, equipment damage, or personal injury resulting from the use of this data.
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