1970 Evinrude 9.5 HP Sportwin Outboard Specs & Part Numbers
Evinrude 9.5 HP Sportwin (1970) Technical Guide
The 1970 Evinrude 9.5 HP Sportwin (Model Series 9022 / 9023) is a highly recognizable and beloved classic outboard motor. Featuring a unique “low-profile” design, it was engineered to provide a low center of gravity, make transport easy, and prevent fishing lines from tangling on the engine cowling. Today, it remains a favorite among vintage outboard collectors and budget boaters due to its robust build quality and excellent trolling capabilities.
1. Overview & Technical Specifications
The Sportwin 9.5 HP utilizes a two-cylinder, two-stroke powerhead. Its compact design was achieved by mounting the powerhead lower in the housing and routing the exhaust and steering mechanisms around it. Below are the core engineering specifications for this model:
| Specification | Value / Measurement |
|---|---|
| Horsepower | 9.5 HP @ 4500 RPM |
| Cylinder Configuration | 2 Cylinders, Inline (2-Stroke) |
| Displacement | 15.2 cubic inches (249 cc) |
| Bore & Stroke | 2.0625″ x 1.700″ (52.39 mm x 43.18 mm) |
| Fuel/Oil Ratio | 50:1 (TC-W3 Outboard Oil to 87 Octane Unleaded Gas) |
| Weight | 60 lbs (approx. 27 kg) |
| Fuel Tank Type | External single-line pressureless tank (standard fuel pump system) |
2. Common Maintenance & Tune-up Specs
Keeping a 1970 Sportwin running smoothly requires regular attention to the ignition system and the cooling circuit. This motor uses the classic OMC Universal Magneto system, which is highly reliable but relies on mechanical points that wear over time.
| Maintenance Item | Specification / Part Number |
|---|---|
| Spark Plug Type | Champion UL81C (Standard) / Champion J4C (Acceptable Alternative) |
| Spark Plug Gap | 0.030 inches (0.76 mm) |
| Point Gap Setting | 0.020 inches (0.51 mm) at high lobe |
| Water Pump Impeller Part | OEM #379764 (Sierra equivalent: 18-3001) |
| Gearcase Lubricant | OMC Hi-Vis or equivalent 80W-90 Marine Gear Lube |
| Carburetor Settings | High Speed: Fixed Jet (#32) Low Speed: Adjustable (Initial setting: 1.5 turns open from gently seated) |
Crucial Service Notes:
- The Flywheel Removal: To service the points and condensers, you must remove the flywheel. Always use a proper harmonic balancer puller utilizing the three threaded holes on the flywheel hub. Do not use a jaw puller on the outer edge of the flywheel, as it will warp or crack the cast aluminum.
- Impeller Replacement: Accessing the water pump impeller requires dropping the lower gearcase. Be sure to disconnect the shift rod connector, which is located behind the small brass access oval plate on the side of the exhaust housing.
3. Notable Features & History
The 9.5 HP Sportwin was introduced by Outboard Marine Corporation (OMC) in 1964 and ran through 1973 under both the Evinrude and Johnson nameplates. It replaced the taller, heavier 10 HP models and was marketed as the ultimate fisherman’s companion.
The “Low-Boy” Low-Profile Design
The defining aesthetic of the 9.5 HP Sportwin is its incredibly short, squat silhouette. Often referred to by enthusiasts as the “Pancake” or “Low-Boy” motor, its top cowls sit several inches lower than contemporary outboards of similar horsepower. This allowed anglers to cast over the back of the boat without fear of snagging their lines on the motor cover.
Innovative Isolation Mounts (And Their Pitfall)
To reduce vibration transmitted to the boat, OMC suspended the entire powerhead of the 9.5 HP inside a rigid outer plastic and metal shell using large rubber motor mounts. While this made the engine incredibly smooth and quiet to operate, it introduced a notorious engineering issue:
- The Exhaust Seal Issue: Over time, the inner rubber exhaust boot (connecting the powerhead exhaust outlet to the lower leg) degrades. When this seal breaks down, exhaust gases escape directly into the surrounding cowling. Because the carburetor draws intake air from inside the cowling, it begins breathing its own exhaust. This starves the engine of oxygen, causing it to idle poorly or stall completely when the cowl cover is on, while running perfectly with the cover off.
Legacy & Collectibility
Despite the potential for exhaust seal degradation, the 1970 Evinrude 9.5 HP remains highly sought after. Parts are still widely available through aftermarket manufacturers like Sierra, and because thousands were produced, complete engines can easily be sourced on the secondary market. If well-maintained, these simple, rugged two-strokes will easily run for another generation.