Yamaha 1984-87 150 HP Outboard Specs & Maintenance
Unleash raw two-stroke power on the water with the iconic 1984–1987 150 HP V6 outboard engine. Featuring a robust 90-degree V6 block displacing 158 cubic inches (2596 cc), this legendary two-stroke motor delivered exceptional holeshot performance and long-lasting durability for mid-80s offshore and performance boats. Whether you are restoring a classic hull or keeping a reliable workhorse running smooth, our comprehensive specs, tuning guides, and maintenance data will help you master every DIY repair.
Complete Technical Specifications
| Specification | Details |
|---|---|
| Model / Horsepower | 150 |
| Year Range | 1984-87 |
| Engine Type | 90 LV 2-st |
| Cylinders | 6 |
| Displacement | 158 cu-in (2596 cc) |
| Bore x Stroke | 3.54 x 2.68 in (90 x 68 mm) |
| Compression Ratio | |
| Full Throttle RPM | 4500-5500 |
| Idle Speed (Neutral) RPM | 675-725 |
| Idle Speed (Trolling) RPM | 550-600 |
| Spark Plug (NGK) | B7HS-10 |
| Spark Plug (Champion) | — |
| Spark Plug Gap | 0.035-0.039 in (0.9-1.0 mm) |
| Ignition System | |
| Ignition Timing (Idle) | 6-8 ATDC |
| Ignition Timing (Carb Pickup) | 5-7 ATDC |
| Ignition Timing (Full Advance) | 23-25 |
| Fuel System | Carb |
| Starting System | Electric |
| Oil Injection System | PB or 50:1 PM |
| Injection Oil Ratio | PB or 50:1 PM |
| Gear Oil Capacity (mL/cc) | 980 |
| Gear Oil Capacity (Oz) | 33.1 |
| Approximate Weight | 392-434 lbs (178-197 kg) |
| Battery CCA / Reserve | 380 (70) |
| Battery Reserve | 124 minutes |
| Tach Pole Setting | 12 |
| Test Propeller Part Number | YB-1626 |
| Test Propeller New Engine RPM | 4600-4800 |
Maintenance Summary
Keeping this 158 cu. in. V6 running smoothly requires consistent ignition care. Always gap your NGK B7HS-10 spark plugs between 0.035–0.039 inches (0.9–1.0 mm). Perform seasonal gearcase oil changes, inspect the water pump impeller, and ensure correct 2-stroke oil mixing to maintain peak compression and reliability.
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Notice: Specifications, fuel ratios, and maintenance guidelines listed on VintageMotorSpecs.com are compiled for historical reference and educational purposes only.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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