1964 Evinrude 9.5 HP Sportwin Outboard Specs & Part Numbers
Technical Guide: 1964 Evinrude 9.5 HP Sportwin
The 1964 Evinrude 9.5 HP Sportwin (Model 9422 / 9423) is one of the most distinctive and recognizable vintage outboard motors ever built by the Outboard Marine Corporation (OMC). Renowned for its ultra-low profile “pancake” design, this motor was engineered to be compact, lightweight, and easy to fish over. It remains a favorite among vintage outboard collectors and classic boat enthusiasts today.
Overview & Technical Specifications
The 9.5 HP Sportwin was introduced in 1964 to replace the aging, taller 10 HP QD series. Its innovative design packed a twin-cylinder powerhead into a highly compressed vertical space, routing the carburetor and intake systems uniquely to keep the overall height to a minimum.
| Specification | Value / Detail |
|---|---|
| Horsepower | 9.5 HP @ 4500 RPM |
| Cylinders | 2 Cylinders (Inline, 2-Stroke) |
| Displacement | 15.2 Cubic Inches (249 cc) |
| Bore & Stroke | 2.0625″ x 1.1406″ (2-1/16″ x 1-9/64″) |
| Fuel/Oil Ratio | 50:1 (Regular unleaded gas to TC-W3 rated outboard oil) |
| Fuel Tank | External 2-line pressurized system (or converted to single-line fuel pump) |
| Weight | Approx. 60 lbs (Dry) |
| Starter Type | Manual Recoil (top pull, horizontal wrap) |
Common Maintenance & Tune-up Specs
Keeping the 9.5 HP Sportwin running smoothly requires regular attention to its ignition system, cooling circuit, and lower unit. Below are the critical tune-up specifications for routine servicing.
Ignition System
- Spark Plugs: Champion J4C or J6C (J6C is slightly hotter and recommended for frequent trolling to prevent fouling).
- Spark Plug Gap:
0.030 inches(0.76 mm) - Point Gap (Dual Points):
0.020 inches(0.51 mm) at high lobe. - Ignition System Type: OMC Universal Magneto (located under the flywheel). Features dual coils, dual points, and dual condensers.
Fuel & Carburetion
- Carburetor Low-Speed Idle Needle: Initial setting is 1.5 turns open from gently seated. Adjust while warm and in forward gear.
- High-Speed Jet: Fixed orifice jet (not adjustable). Clean with aerosol carb cleaner and compressed air; never use wire to clean the brass orifice.
Cooling & Gearcase
- Impeller Part Number: OMC / Evinrude Part #
277181(or Sierra18-3001). - Gearcase Lubricant: OMC Premium Blend (Type C) or high-quality 80W-90 marine gear lube.
- Gearcase Capacity: Approximately 8.5 oz. Fill from the bottom drain plug until oil flows out the top vent plug.
Notable Features & History
The “Pancake” Low-Profile Design
Before 1964, outboard motors in the 10-horsepower class stood tall and upright on boat transoms. Evinrude designed the 9.5 HP Sportwin to sit low—barely extending above the top of the transom. This compact design was achieved by mounting the powerhead low, angling the recoil starter horizontally across the top, and wrapping the exhaust and intake plumbing tightly around the crankcase. This made it incredibly easy for anglers to cast lines directly over the back of the boat without snagging.
The “Cowl Exhaust” Trap
One of the most famous quirks of the 9.5 HP Sportwin is its susceptibility to swallowing its own exhaust gas. The motor is suspended inside an outer decorative housing by rubber mounts, sealed with a rubber boot around the exhaust housing.
If this exhaust seal or the upper motor mounts deteriorate, exhaust gas can leak into the interior of the motor housing. Because the carburetor draws intake air from inside the cowl, it will suck in this oxygen-depleted exhaust gas, causing the motor to bog down, idle poorly, or die when the cowl is latched.
Pro Tip: If your 9.5 HP runs perfectly with the engine cover off but dies when you put the cover on, you have an internal exhaust leak.
Vibration Isolation
To deliver a smooth ride, OMC suspended the entire powerhead on three soft rubber mounts. This decoupled engine vibration from the boat’s transom, making the Sportwin one of the quietest and smoothest-running trolling motors of its era. However, after decades of exposure to fuel and oil, these original rubber mounts often degrade, requiring replacement to restore structural stability and seal integrity.