Honda Marine 4-Stroke 8-15HP Outboard Engine Parts

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This page is for Honda 4‑Stroke 8–15HP outboard engines. It helps you find compatible parts and service information, with maintenance tips, common replacement parts, and troubleshooting guidance. You can also browse the main Honda collection. Scroll to the bottom of this page to start browsing parts for this engine. On the collection page, use the Filter & Sort controls to narrow results by horsepower, year range, and part category.

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How to Identify Your 8–15HP Model

Find the nameplate/serial label on the transom bracket or swivel bracket. Record the full model code and serial number.
Model code tips: BF8/BF9.9 indicate the 8–9.9 HP platform; BF15 indicates the 15 HP platform. Suffix letters often denote shaft length (S/L), manual vs. electric start, and tiller vs. remote control.
Platform differences: 8–9.9 HP and 15–20 HP portables are different platforms. Many parts are shared within each platform but not across them.
4‑Stroke specifics: confirm whether your engine uses a spin‑on oil filter and note any charging system options (these can affect parts selection).

Platform Overview

Portable 8–9.9 HP (e.g., BF8 / BF9.9)

Feature	Description
Configuration	Inline‑2 4‑stroke portable. Induction may be carbureted or EFI depending on year; manual or electric start; tiller or remote options.
Common Models	BF8, BF9.9 (various suffixes for shaft length and controls)
Advantages	Lightweight, quiet operation, strong trolling manners, good fuel economy.
Notes	Water pump kits, gearcase seals, and some ignition parts differ from the 15–20 HP platform. Verify by model code and serial.

Portable 15–20 HP (e.g., BF15 / BF20)

Feature	Description
Configuration	Inline‑2 4‑stroke portable. Induction may be carbureted or EFI depending on year; tiller or remote; manual or electric start.
Common Models	BF15, BF20 (various suffixes for shaft length and controls)
Advantages	Responsive mid‑range torque, portable weight class, versatile for fishing and utility boats.
Notes	Many service parts interchange between 15 and 20 HP models, but differ from 8–9.9 HP units. Confirm prop hub spline, water pump kit, and gasket compatibility by serial.

Routine Maintenance & Service Parts

Intervals below are general guidelines for typical recreational use. Always confirm procedures and schedules in your official Honda service manual for your specific model and serial range.

Item	Interval*	Remarks	Parts Link
Engine oil + filter	Every 100 hrs or annually	Use FC‑W 4‑stroke marine oil. Replace spin‑on filter where equipped.	Oil Filters
Gear oil (lower unit)	Every 100 hrs or annually; after submersion	Inspect for water intrusion/metal. Replace seals if contamination is found.	Honda Lower Unit Seal Kits
Spark plugs	Inspect 100 hrs; replace 200 hrs or 1–2 seasons	Check gap and insulator color; replace if fouled or worn.	Spark Plugs
Fuel filter / water separator	Inspect 50 hrs; replace annually	Replace inline filter; drain/replace any external water‑separating element.	Fuel Filters
Water pump impeller / kit	Every 2–3 seasons or 200 hrs	Replace sooner if tell‑tale is weak or engine overheats.	Honda Water Pump Repair Kits
Anodes (sacrificial zincs)	Inspect 50 hrs; replace when 50% depleted	Match material to water type (zinc/aluminum/magnesium).	Anodes

Frequently Used Parts Categories

Routine Service: Service & Maintenance Kits
Cooling System: Honda Water Pump Repair Kits
Fuel System: Fuel Filters
Ignition / Electrical: Electrical Items
Corrosion Protection: Anodes
Propulsion: Propellers
Gearcase Service: Honda Lower Unit Seal Kits

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Weak tell‑tale or overheat alarm	Inspect intake screens for debris; verify strong primer bulb; check impeller condition and thermostat operation.	Water pump repair kit, thermostat, intake screen, gaskets
Hard starting / rough idle	Confirm fresh fuel and proper priming; check spark plug condition/gap; look for fuel leaks or air ingress; clean carburetor passages (or verify EFI basics).	Spark plugs, fuel filter, carburetor kit/cleaner, primer bulb, hoses/clamps
Poor acceleration / power loss	Check prop for damage or incorrect pitch; verify fuel tank venting; drain water from separator; compression and ignition check if needed.	Propeller, fuel filter/water separator, spark plugs
Gearcase noise or metal in oil	Drain gear oil and inspect; check for milky oil (water); examine prop shaft for fishing line; pressure/vac test for seal integrity.	Lower unit seal kit, prop shaft seals, bearings, gear lube

FAQs

Are parts interchangeable between 8–9.9 HP and 15–20 HP models?

Many fasteners and accessories may be similar, but the 8–9.9 HP platform and 15–20 HP platform use different powerheads and gearcases. Always verify part compatibility by full model code and serial number.

When should I replace the water pump impeller?

As a preventative measure, replace the impeller about every 2–3 seasons or ~200 hours, sooner if the tell‑tale weakens, the engine overheats, or you’ve ingested sand/silt.

How often should I change the lower unit gear oil?

At least every 100 hours or annually, and immediately after any submersion event. If water or metal is found, service the seals before returning to use.

What information do you need to confirm part compatibility?

Please provide the full model code, serial number, shaft length (S/L/XL), tiller vs. remote, and whether the engine has electric start or charging. Photos of the nameplate and the part to be replaced are very helpful.

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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.