Yamaha 70HP 2-Stroke Outboard Engine

(66 products)

This page is dedicated to Yamaha 2-Stroke 70 HP outboard engines. Use it to find compatible parts and practical service information, including maintenance tips, commonly replaced components, and troubleshooting guidance. You can also browse the main Yamaha outboard collection. Scroll to the bottom of this page to begin browsing parts for this engine. On the collection page, use the “Filter & Sort” controls to narrow results by horsepower, year range, and part category/section.

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How to Identify Your 70 HP Model

Nameplate location: Look for the ID/serial plate on the transom clamp bracket or the swivel bracket (typically port side). It shows the model code, production year code, and serial number.
Reading the model code: The letters often indicate shaft length (S 15", L 20", X 25"), tiller vs. remote control, and starting/trim features. The suffix can indicate year or revision.
2‑Stroke specifics: Most 70 HP 2‑strokes are inline‑3 carbureted engines with CDI ignition. Many use Yamaha Autolube oil injection; verify if your engine is premix or oil‑injected.
Platform differences: Some model families may appear as “70” or “C70” variants. Parts like water pump kits, gearcase seals, and prop hubs can vary—confirm with the exact model and serial.

Engine/Platform Overview

Inline‑3 2‑Stroke 70 HP

Feature	Description
Configuration	Inline‑3, 2‑Stroke, carbureted fuel system, CDI ignition; displacement ~849 cm³ (approx. 51.8 cu. in.).
Common Models	70 HP 2‑Stroke inline‑3 models; various 70/C70 and 70TL‑type variants depending on year, shaft length, and controls.
Advantages	Lightweight package with good hole‑shot and mid‑range performance; simple carburetion aids field serviceability.
Notes	Verify oiling type (premix vs. Autolube). Water pump and gearcase parts may differ by production year and shaft length—confirm with model/serial.

Routine Maintenance & Service Parts

Intervals below are general guidelines for typical recreational use; always follow the official Yamaha service manual for your exact model and operating conditions.

Item	Interval*	Remarks	Parts Link
Gear oil (lower unit)	Every 100 hours or annually	Inspect magnetic drain plug; milky oil indicates water intrusion—service seals.	Yamaha Lower Unit Seal Kits
Spark plugs	Inspect 50 hours; replace ~100 hours or annually	Use the specified heat range and gap; replace sooner if fouling or misfire occurs.	Spark Plugs
Fuel filter (inline/under‑cowl)	Inspect every 50 hours; replace ~100 hours or as needed	Drain/replace if water or debris is present; also service any external separator on the boat.	Fuel Filters
Water pump impeller/kit	Every 2–3 seasons or ~200 hours (yearly in silty/shallow use)	Restores cooling flow and overheat protection; replace housing if scored.	Yamaha Water Pump Repair Kits
Anodes (external & internal)	Inspect every 50 hours; replace when ~50% depleted	Match anode material to water type (aluminum for brackish/salt, magnesium for fresh, zinc for traditional saltwater).	Yamaha Anodes
Oil injection system service (if equipped)	Annually	Inspect/clean strainer, verify pump linkage and alarms; confirm correct oil delivery.	Yamaha Service & Maintenance Kits
Propeller removal & spline lube	Every 100 hours or seasonally	Check for fishing line at seals; inspect hub for slip; apply marine grease to the shaft.	Yamaha Propellers

Frequently Used Parts Categories

Routine Service — Yamaha Service & Maintenance Kits
Cooling System — Yamaha Water Pump Repair Kits
Fuel System — Fuel Filters and Fuel Pumps
Ignition / Electrical — Electrical Items
Corrosion Protection — Yamaha Anodes
Propellers & Hubs — Yamaha Propellers
Gearcase & Seals — Yamaha Lower Unit Seal Kits

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Weak tell‑tale stream or overheat alarm	Verify intake screen is clear; inspect impeller and pump housing; check thermostat function.	Water pump kit, thermostat, intake screen, anodes.
Poor acceleration or power loss	Inspect prop for damage or hub slip; replace fuel filter; check fuel pump output and spark quality.	Propeller, fuel filter, fuel pump, spark plugs, carburetor service parts.
Hard starting or rough idle	Confirm cold‑start enrichment/choke operation; inspect plugs and plug wires; drain stale fuel and clean carbs.	Spark plugs, fuel filter, fuel hoses, carburetor rebuild components.
Excessive smoke (2‑Stroke)	Verify correct oiling (premix ratio or injection setting); check oil pump and check valves; avoid prolonged rich idling.	Oil injection components, spark plugs, carburetor adjustments.
Gearcase noise or metal in gear oil	Check prop shaft for line damage; pressure test gearcase; inspect seals and bearings.	Lower unit seal kit, bearings/gear set, prop hub.

FAQs

Are parts interchangeable across different years or 70 HP platforms?

Many fasteners and service items are shared, but components like water pump kits, gearcase seals, ignition parts, and prop hubs can vary by year, shaft length, and control type. Always verify using your exact model code and serial.

When should I replace the water pump impeller?

As a rule of thumb, every 2–3 seasons or ~200 hours, and yearly if you operate in sandy, silty, or shallow water. Replace sooner if you notice weak tell‑tale flow or elevated running temperature.

How often should the lower unit gear oil be changed?

Service gear oil every 100 hours or once per season. If the drained oil looks milky, has metal debris, or a burnt smell, inspect seals and internal components before continued use.

What information helps confirm part compatibility?

Provide the full model code and serial number from the nameplate, shaft length, control type (tiller or remote), approximate year, and photos of the part or area being serviced.

Ready to find parts for your Yamaha 2‑Stroke 70 HP outboard? Browse the main Yamaha outboard collection and use Filter & Sort by horsepower, year range, and category.

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If you’re unsure about your model, send us a photo of the nameplate and the part you need and we’ll help verify compatibility.