Yamaha 1984-92 140 HP Outboard Specs & Maintenance
Built between 1984 and 1992, this 140 HP 90° V4 two-stroke outboard motor remains a favorite among classic powerboating enthusiasts. Packing 106 cubic inches (1730 cc) of displacement across four cylinders, this high-output workhorse delivers an exceptional power-to-weight ratio for vintage sport boats. Whether you are restoring a classic hull or performing routine seasonal maintenance, our database provides the technical specifications and expert guidance DIY mechanics need to keep this engine running strong.
Complete Technical Specifications
| Specification | Details |
|---|---|
| Model / Horsepower | 140 |
| Year Range | 1984-92 |
| Engine Type | 90 LV 2-st |
| Cylinders | 4 |
| Displacement | 106 cu-in (1730 cc) |
| Bore x Stroke | |
| Compression Ratio | |
| Full Throttle RPM | 5000-6000 |
| Idle Speed (Neutral) RPM | 700-800 |
| Idle Speed (Trolling) RPM | 600-700 |
| Spark Plug (NGK) | B9HS-10 |
| Spark Plug (Champion) | L77J4 |
| Spark Plug Gap | 0.035-0.039 in (0.9-1.0 mm) |
| Ignition System | CDI |
| Ignition Timing (Idle) | 4-6 ATDC |
| Ignition Timing (Carb Pickup) | 3-5 ATDC |
| Ignition Timing (Full Advance) | 21-23 |
| 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) | 790 |
| Gear Oil Capacity (Oz) | 26.9 |
| Approximate Weight | |
| Battery CCA / Reserve | 380 (70) |
| Battery Reserve | 124 minutes |
| Tach Pole Setting | 12 |
| Test Propeller Part Number | YB-1624 |
| Test Propeller New Engine RPM | 5200-5400 |
Maintenance Summary
Keeping your 140 HP V4 performing reliably requires consistent ignition and fuel system maintenance. Ensure crisp combustion by installing fresh NGK B9HS-10 spark plugs gapped to 0.035–0.039 inches (0.9–1.0 mm). Regularly inspect the water pump impeller, lower unit gear lube, and fuel lines to maximize engine life.
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Notice: Specifications, fuel ratios, and maintenance guidelines listed on VintageMotorSpecs.com are compiled for historical reference and educational purposes only.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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