{"title":"Yamaha 2-Stroke Outboard Marine Engine Parts 9.9-250HP","description":"\u003csection id=\"hero\" style=\"padding:16px;max-width:1000px;margin:0 auto;\"\u003e\n  \u003cp\u003eThis page is for Yamaha 2‑Stroke 9.9–250HP outboard engines. Use it to quickly locate compatible parts and practical service information, including maintenance tips, commonly replaced items, and troubleshooting guidance. You can also browse the main Yamaha collection; scroll to the bottom of this page to start browsing parts for this engine, and remember you can use the collection page’s Filter \u0026amp; Sort controls to narrow results by horsepower, year range, and part category.\u003c\/p\u003e\n  \u003ca href=\"https:\/\/seasierra.com\/collections\/yamaha\" style=\"display:inline-block;padding:10px 16px;border:1px solid #0a5;border-radius:6px;text-decoration:none;\"\u003eBrowse All Yamaha Parts\u003c\/a\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"identify-model\" style=\"padding:16px;max-width:1000px;margin:0 auto;\"\u003e\n  \u003ch2\u003eHow to Identify Your 9.9–250HP Model\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eNameplate location: Look for the aluminum ID plate on the transom bracket or swivel bracket. It lists the model code and serial number.\u003c\/li\u003e\n    \u003cli\u003eModel code and suffix: Letters often indicate shaft length (S\/L\/X), manual vs. electric start, tiller vs. remote, and other options. Record the full code and serial for exact parts matching.\u003c\/li\u003e\n    \u003cli\u003ePlatform cues: Small 2‑strokes (9.9–30HP) are typically inline‑2; midrange families (40–90HP) are often inline‑3; 115–130HP are inline‑4; 150–250HP are V6 (carb, EFI\/OX66, or HPDI). Visual cues include cylinder bank layout, number of carbs\/injectors, and cowling labels.\u003c\/li\u003e\n    \u003cli\u003eOil system: Many Yamaha 2‑strokes use oil injection tanks; some earlier portables require premix. Check your cowling decals and owner’s manual before servicing.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"platforms\" style=\"padding:16px;max-width:1000px;margin:0 auto;\"\u003e\n  \u003ch2\u003ePlatform Overview\u003c\/h2\u003e\n\n  \u003ch3\u003ePortable Twins (9.9–20HP)\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eDescription\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eConfiguration\u003c\/td\u003e\n        \u003ctd\u003eInline‑2 carbureted 2‑stroke\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eCommon Models\u003c\/td\u003e\n        \u003ctd\u003e9.9\/15\/20HP two‑cylinder families\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAdvantages\u003c\/td\u003e\n        \u003ctd\u003eLightweight, simple, easy to maintain and transport\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eNotes\u003c\/td\u003e\n        \u003ctd\u003eKeep fuel fresh; service impeller regularly; verify premix vs. oil‑injection setup\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch3\u003eSmall Twins (25–30HP)\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eDescription\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eConfiguration\u003c\/td\u003e\n        \u003ctd\u003eInline‑2 carbureted 2‑stroke\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eCommon Models\u003c\/td\u003e\n        \u003ctd\u003e25–30HP two‑cylinder platforms (e.g., C25\/C30 families)\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAdvantages\u003c\/td\u003e\n        \u003ctd\u003eLow weight with solid thrust for small craft\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eNotes\u003c\/td\u003e\n        \u003ctd\u003eService spark plugs and impeller; verify gearcase ratio when selecting props\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch3\u003eMidrange Inline‑3 (40–90HP)\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eDescription\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eConfiguration\u003c\/td\u003e\n        \u003ctd\u003eInline‑3 carbureted 2‑stroke (popular 40\/50\/60\/70\/75\/85\/90HP families)\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eCommon Models\u003c\/td\u003e\n        \u003ctd\u003e40–90HP inline‑3 ranges\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAdvantages\u003c\/td\u003e\n        \u003ctd\u003eStrong mid‑range torque, proven reliability, broad parts availability\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eNotes\u003c\/td\u003e\n        \u003ctd\u003eCarb sync and clean idle circuits are critical for smooth starts and acceleration\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch3\u003eInline‑4 (115–130HP)\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eDescription\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eConfiguration\u003c\/td\u003e\n        \u003ctd\u003eInline‑4 carbureted 2‑stroke\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eCommon Models\u003c\/td\u003e\n        \u003ctd\u003e115\/130HP inline‑4 families\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAdvantages\u003c\/td\u003e\n        \u003ctd\u003eGood power‑to‑weight and robust gearcases\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eNotes\u003c\/td\u003e\n        \u003ctd\u003eConfirm thermostat and cooling parts by model code; use correct prop hub hardware\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch3\u003eV6 Carb\/EFI (150–200HP)\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eDescription\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eConfiguration\u003c\/td\u003e\n        \u003ctd\u003eV6 carbureted and early EFI (OX66) 2‑stroke\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eCommon Models\u003c\/td\u003e\n        \u003ctd\u003e150\/175\/200HP V6 families\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAdvantages\u003c\/td\u003e\n        \u003ctd\u003eHigh output with straightforward maintenance\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eNotes\u003c\/td\u003e\n        \u003ctd\u003eKeep fuel and cooling systems clean; inspect oil‑injection tanks\/filters and bleed per manual\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\n  \u003ch3\u003eV6 OX66\/HPDI (200–250HP)\u003c\/h3\u003e\n  \u003ctable style=\"width:100%;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eFeature\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eDescription\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eConfiguration\u003c\/td\u003e\n        \u003ctd\u003eV6 EFI (OX66) and High‑Pressure Direct Injection (HPDI) 2‑stroke\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eCommon Models\u003c\/td\u003e\n        \u003ctd\u003e200\/225\/250HP OX66 \u0026amp; HPDI ranges\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAdvantages\u003c\/td\u003e\n        \u003ctd\u003eStrong top‑end with efficient fuel delivery for the era\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eNotes\u003c\/td\u003e\n        \u003ctd\u003eUse clean, water‑free fuel; maintain filters and high‑pressure components; ensure cooling system is in top condition\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"service-kits\" style=\"padding:16px;max-width:1000px;margin:0 auto;\"\u003e\n  \u003ch2\u003eRoutine Maintenance \u0026amp; Service Parts\u003c\/h2\u003e\n  \u003cp\u003eIntervals below are general guidelines for Yamaha 2‑stroke outboards. Always follow the official service manual for your exact model, usage, and environment.\u003c\/p\u003e\n  \u003ctable style=\"width:100%;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eItem\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eInterval*\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eRemarks\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eParts Link\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eGear oil (lower unit)\u003c\/td\u003e\n        \u003ctd\u003eEvery 100 hours or annually\u003c\/td\u003e\n        \u003ctd\u003eCheck for water or metal; pressure test if oil appears milky\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/yamaha-lower-unit-seal-kits\"\u003eYamaha Lower Unit Seal Kits\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eSpark plugs\u003c\/td\u003e\n        \u003ctd\u003eInspect 50–100 hours; replace as needed or annually\u003c\/td\u003e\n        \u003ctd\u003eUse correct heat range and gap; fouling may indicate carb or oiling issues\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/spark-plug\"\u003eSpark Plugs\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eFuel filter \/ water separator\u003c\/td\u003e\n        \u003ctd\u003eEvery 50–100 hours or annually\u003c\/td\u003e\n        \u003ctd\u003eCritical for carb, EFI, and HPDI systems; keep water out of fuel\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/fuel-filters-1\"\u003eFuel Filters\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eWater pump impeller \/ kit\u003c\/td\u003e\n        \u003ctd\u003eEvery 100 hours or annually\u003c\/td\u003e\n        \u003ctd\u003eShorten interval for sandy\/silty water or heavy trolling\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/yamaha-water-pump-repair-kits\"\u003eYamaha Water Pump Repair Kits\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eAnodes (internal \u0026amp; external)\u003c\/td\u003e\n        \u003ctd\u003eInspect frequently; replace when ~50% consumed\u003c\/td\u003e\n        \u003ctd\u003eSelect the right alloy for salt, brackish, or fresh water; keep bonding clean\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/yamaha-anodes\"\u003eYamaha Anodes\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eThermostat(s)\u003c\/td\u003e\n        \u003ctd\u003eInspect annually; replace every 2–3 years or if running hot\/cold\u003c\/td\u003e\n        \u003ctd\u003eImpacts smoke level, idle quality, and EFI\/HPDI fuel control\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/yamaha-outboard-parts\"\u003eYamaha Outboard Parts\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eOil‑injection tank filter \u0026amp; lines\u003c\/td\u003e\n        \u003ctd\u003eInspect annually; service every 2 years\u003c\/td\u003e\n        \u003ctd\u003eClean tank, replace strainer\/lines as needed; bleed system per manual\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/hoses\"\u003eHoses\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003ePropeller \u0026amp; hub hardware\u003c\/td\u003e\n        \u003ctd\u003eRemove and grease splines each season\u003c\/td\u003e\n        \u003ctd\u003eCheck for fishing line at seals; verify pitch and hub type\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/yamaha-propellers\"\u003eYamaha Propellers\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eLower unit seal kit (if water in oil)\u003c\/td\u003e\n        \u003ctd\u003eAs needed after pressure test\u003c\/td\u003e\n        \u003ctd\u003eReplace affected seals and retest; confirm vent\/drain screw gaskets\u003c\/td\u003e\n        \u003ctd\u003e\u003ca href=\"https:\/\/seasierra.com\/collections\/yamaha-lower-unit-seal-kits\"\u003eYamaha Lower Unit Seal Kits\u003c\/a\u003e\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"common-parts\" style=\"padding:16px;max-width:1000px;margin:0 auto;\"\u003e\n  \u003ch2\u003eFrequently Used Parts Categories\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eRoutine Service Kits – \u003ca href=\"https:\/\/seasierra.com\/collections\/yamaha-service-maintenance-kits\"\u003eYamaha Service \u0026amp; Maintenance Kits\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eCooling System – \u003ca href=\"https:\/\/seasierra.com\/collections\/yamaha-water-pump-repair-kits\"\u003eYamaha Water Pump Repair Kits\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eFuel System – \u003ca href=\"https:\/\/seasierra.com\/collections\/fuel-filters-1\"\u003eFuel Filters\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eIgnition \u0026amp; Starting – \u003ca href=\"https:\/\/seasierra.com\/collections\/spark-plug\"\u003eSpark Plugs\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003eCorrosion Protection – \u003ca href=\"https:\/\/seasierra.com\/collections\/yamaha-anodes\"\u003eYamaha Anodes\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003ePropellers \u0026amp; Hubs – \u003ca href=\"https:\/\/seasierra.com\/collections\/yamaha-propellers\"\u003eYamaha Propellers\u003c\/a\u003e\n\u003c\/li\u003e\n    \u003cli\u003ePerformance \u0026amp; Safety – \u003ca href=\"https:\/\/seasierra.com\/collections\/outboard-hydrofoil-stabilizers\"\u003eOutboard Hydrofoil Stabilizers\u003c\/a\u003e and \u003ca href=\"https:\/\/seasierra.com\/collections\/propeller-guards\"\u003ePropeller Guards\u003c\/a\u003e\n\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"troubleshooting\" style=\"padding:16px;max-width:1000px;margin:0 auto;\"\u003e\n  \u003ch2\u003eCommon Symptoms \u0026amp; Quick Checks\u003c\/h2\u003e\n  \u003ctable style=\"width:100%;border-collapse:collapse;\"\u003e\n    \u003cthead\u003e\n      \u003ctr\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eSymptom\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eCheck First\u003c\/th\u003e\n        \u003cth style=\"text-align:left;border-bottom:1px solid #ddd;\"\u003eRelated Parts\u003c\/th\u003e\n      \u003c\/tr\u003e\n    \u003c\/thead\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eWeak tell‑tale stream or overheat alarm\u003c\/td\u003e\n        \u003ctd\u003eIntake screens for debris, pinched hoses, worn impeller, stuck thermostat\u003c\/td\u003e\n        \u003ctd\u003eWater pump kit, thermostat, intake screens, hoses\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003ePoor acceleration \/ power loss\u003c\/td\u003e\n        \u003ctd\u003eOld fuel, clogged filters, carb jets, weak fuel pump, prop hub slippage\u003c\/td\u003e\n        \u003ctd\u003eFuel filters, fuel pump, carburetor service parts, spark plugs, propeller\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eHard starting \/ rough idle\u003c\/td\u003e\n        \u003ctd\u003eSpark plug condition and gap, primer bulb, choke\/enrichment operation, carb sync\u003c\/td\u003e\n        \u003ctd\u003eSpark plugs, fuel hoses, carburetor components\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eExcessive smoke (2‑stroke)\u003c\/td\u003e\n        \u003ctd\u003eThermostat stuck open (cold running), oil pump setting, choke stuck on\u003c\/td\u003e\n        \u003ctd\u003eThermostat, oil‑injection service parts, choke\/enrichment components\u003c\/td\u003e\n      \u003c\/tr\u003e\n      \u003ctr\u003e\n        \u003ctd\u003eGearcase noise or milky gear oil\u003c\/td\u003e\n        \u003ctd\u003eOil level\/condition, water intrusion, fishing line at prop shaft seals\u003c\/td\u003e\n        \u003ctd\u003eLower unit seal kit, drain\/vent screw gaskets, bearings\u003c\/td\u003e\n      \u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"faq\" style=\"padding:16px;max-width:1000px;margin:0 auto;\"\u003e\n  \u003ch2\u003eFAQs\u003c\/h2\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eAre parts interchangeable between different years or platforms?\u003c\/summary\u003e\n    \u003cp\u003eSome hardware is shared within the same platform family (for example, many inline‑3 70–90HP components), but differences by year, shaft length, ignition, and fuel system are common. Confirm with your full model code and serial number before ordering.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhen should I replace the impeller?\u003c\/summary\u003e\n    \u003cp\u003eAs a general rule, replace the water pump impeller every 100 hours or annually, and sooner if operating in sandy or silty water or if the tell‑tale stream weakens.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eHow often should I change gear oil?\u003c\/summary\u003e\n    \u003cp\u003eChange lower unit gear oil every 100 hours or once per season. If the oil appears milky or you find metal shavings, pressure test the gearcase and service the seals before further use.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat information do you need to verify part compatibility?\u003c\/summary\u003e\n    \u003cp\u003ePlease provide the full Yamaha model code, serial number, horsepower, shaft length, and options (e.g., power trim). A clear photo of the nameplate and the part needing replacement is very helpful.\u003c\/p\u003e\n  \u003c\/details\u003e\n\u003c\/section\u003e\n\n\u003csection id=\"cta\" style=\"padding:16px;max-width:1000px;margin:0 auto;\"\u003e\n  \u003cp\u003eReady to browse by horsepower, year, and model? Start with the main Yamaha collection and use Filter \u0026amp; Sort to narrow results.\u003c\/p\u003e\n  \u003ca href=\"https:\/\/seasierra.com\/collections\/yamaha\" style=\"display:inline-block;padding:10px 16px;border:1px solid #0a5;border-radius:6px;text-decoration:none;\"\u003eShop Yamaha Parts\u003c\/a\u003e\n  \u003cp style=\"margin-top:8px;\"\u003eIf you’re unsure about your model, send us a photo of the nameplate and the part you need and we’ll help verify compatibility.\u003c\/p\u003e\n\u003c\/section\u003e","products":[{"product_id":"thermostat-fits-yamaha-2-stroke-3-250hp-replaces-6e5-12411-30-00-6e5-12411-20-00","title":"Yamaha Outboard Thermostat – 50°C, Fits 2-Stroke 75–250 HP (Replaces 6E5-12411-30, 688-12411-10, 688-12411-11)","description":"\u003csection\u003e\n\u003cstyle\u003e\n  .ss-table-wrap { overflow-x:auto; -webkit-overflow-scrolling:touch; }\n  table.ss-table { width:100%; border-collapse:collapse; min-width:640px; }\n  table.ss-table th, table.ss-table td {\n    padding:10px 12px; border:1px solid #e5e7eb; text-align:left; vertical-align:top;\n  }\n  table.ss-table th {\n    white-space:nowrap;\n    word-break:normal;\n    letter-spacing:normal;\n    font-weight:600;\n    background:#f8fafc;\n  }\n  @media (max-width:480px){\n    table.ss-table th, table.ss-table td { padding:8px 10px; font-size:14px; }\n  }\n\u003c\/style\u003e\n\n\u003csection\u003e\n\u003ch2\u003eProduct Details\u003c\/h2\u003e\n\u003cp\u003eThis Yamaha outboard thermostat is a 50°C replacement component for selected Yamaha two-stroke and two-stroke HPDI outboard engines. It helps regulate engine operating temperature by controlling coolant flow through the outboard cooling system.\u003c\/p\u003e\n\u003cp\u003eThe thermostat corresponds to Yamaha OEM part number \u003cstrong\u003e6E5-12411-30\u003c\/strong\u003e and supersedes \u003cstrong\u003e688-12411-10\u003c\/strong\u003e and \u003cstrong\u003e688-12411-11\u003c\/strong\u003e. Confirm the exact model designation and engine configuration before ordering.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e50°C operating temperature.\u003c\/li\u003e\n\u003cli\u003eReplacement thermostat for selected Yamaha two-stroke outboards.\u003c\/li\u003e\n\u003cli\u003eDesigned for service replacement in the thermostat housing.\u003c\/li\u003e\n\u003cli\u003eThermostat only; gasket is not included unless specifically stated in the package contents.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/section\u003e\n\n\u003csection\u003e\n\u003ch2\u003ePart Number References\u003c\/h2\u003e\n\u003cp\u003eThese manufacturer part numbers identify the thermostat application covered by this listing. Part-number references do not replace verification of the complete engine model and configuration.\u003c\/p\u003e\n\u003cdiv class=\"ss-table-wrap\"\u003e\n\u003ctable class=\"ss-table\" aria-label=\"Part Number References\"\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eReference Type\u003c\/th\u003e\n\u003cth\u003ePart Number\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eCurrent Yamaha OEM reference\u003c\/td\u003e\n\u003ctd\u003e6E5-12411-30\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuperseded Yamaha reference\u003c\/td\u003e\n\u003ctd\u003e688-12411-10\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSuperseded Yamaha reference\u003c\/td\u003e\n\u003ctd\u003e688-12411-11\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\n\u003csection\u003e\n\u003ch2\u003eEngine Compatibility\u003c\/h2\u003e\n\u003cp\u003eThis thermostat is listed for the following Yamaha outboard models and configurations. The model, horsepower, stroke type and HPDI designation must all match your engine.\u003c\/p\u003e\n\u003cdiv class=\"ss-table-wrap\"\u003e\n\u003ctable class=\"ss-table\" aria-label=\"Yamaha Two-Stroke Outboard Compatibility\"\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\n\u003cth\u003eModel\u003c\/th\u003e\n\u003cth\u003eRated HP\u003c\/th\u003e\n\u003cth\u003eStroke \/ Configuration\u003c\/th\u003e\n\u003cth\u003eOperating Temperature\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003e75C\u003c\/td\u003e\n\u003ctd\u003e75 HP\u003c\/td\u003e\n\u003ctd\u003eTwo-Stroke\u003c\/td\u003e\n\u003ctd\u003e50°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003e90A\u003c\/td\u003e\n\u003ctd\u003e90 HP\u003c\/td\u003e\n\u003ctd\u003eTwo-Stroke\u003c\/td\u003e\n\u003ctd\u003e50°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003e100A\u003c\/td\u003e\n\u003ctd\u003e100 HP\u003c\/td\u003e\n\u003ctd\u003eTwo-Stroke\u003c\/td\u003e\n\u003ctd\u003e50°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003e115C\u003c\/td\u003e\n\u003ctd\u003e115 HP\u003c\/td\u003e\n\u003ctd\u003eTwo-Stroke\u003c\/td\u003e\n\u003ctd\u003e50°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003e130B\u003c\/td\u003e\n\u003ctd\u003e130 HP\u003c\/td\u003e\n\u003ctd\u003eTwo-Stroke\u003c\/td\u003e\n\u003ctd\u003e50°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003e150F\u003c\/td\u003e\n\u003ctd\u003e150 HP\u003c\/td\u003e\n\u003ctd\u003eTwo-Stroke\u003c\/td\u003e\n\u003ctd\u003e50°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003e175D\u003c\/td\u003e\n\u003ctd\u003e175 HP\u003c\/td\u003e\n\u003ctd\u003eTwo-Stroke\u003c\/td\u003e\n\u003ctd\u003e50°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003e200F\u003c\/td\u003e\n\u003ctd\u003e200 HP\u003c\/td\u003e\n\u003ctd\u003eTwo-Stroke\u003c\/td\u003e\n\u003ctd\u003e50°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003e200G\u003c\/td\u003e\n\u003ctd\u003e200 HP\u003c\/td\u003e\n\u003ctd\u003eTwo-Stroke\u003c\/td\u003e\n\u003ctd\u003e50°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003e225D\u003c\/td\u003e\n\u003ctd\u003e225 HP\u003c\/td\u003e\n\u003ctd\u003eTwo-Stroke\u003c\/td\u003e\n\u003ctd\u003e50°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003e250B\u003c\/td\u003e\n\u003ctd\u003e250 HP\u003c\/td\u003e\n\u003ctd\u003eTwo-Stroke\u003c\/td\u003e\n\u003ctd\u003e50°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eZ150P\u003c\/td\u003e\n\u003ctd\u003e150 HP\u003c\/td\u003e\n\u003ctd\u003eTwo-Stroke HPDI\u003c\/td\u003e\n\u003ctd\u003e50°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eZ150Q\u003c\/td\u003e\n\u003ctd\u003e150 HP\u003c\/td\u003e\n\u003ctd\u003eTwo-Stroke HPDI\u003c\/td\u003e\n\u003ctd\u003e50°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eZ175G\u003c\/td\u003e\n\u003ctd\u003e175 HP\u003c\/td\u003e\n\u003ctd\u003eTwo-Stroke HPDI\u003c\/td\u003e\n\u003ctd\u003e50°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eZ200N\u003c\/td\u003e\n\u003ctd\u003e200 HP\u003c\/td\u003e\n\u003ctd\u003eTwo-Stroke HPDI\u003c\/td\u003e\n\u003ctd\u003e50°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eYamaha\u003c\/td\u003e\n\u003ctd\u003eZ200P\u003c\/td\u003e\n\u003ctd\u003e200 HP\u003c\/td\u003e\n\u003ctd\u003eTwo-Stroke HPDI\u003c\/td\u003e\n\u003ctd\u003e50°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003cp\u003e\u003cstrong\u003eImportant:\u003c\/strong\u003e The compatibility information above is limited to the listed model designations. Do not assume compatibility with every Yamaha two-stroke engine within the same horsepower range.\u003c\/p\u003e\n\u003c\/section\u003e\n\n\u003csection\u003e\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003cdl\u003e\n\u003cdt\u003eProduct Type\u003c\/dt\u003e\n\u003cdd\u003eOutboard engine thermostat\u003c\/dd\u003e\n\u003cdt\u003eOperating Temperature\u003c\/dt\u003e\n\u003cdd\u003e50°C\u003c\/dd\u003e\n\u003cdt\u003eApplication\u003c\/dt\u003e\n\u003cdd\u003eSelected Yamaha two-stroke and two-stroke HPDI outboards\u003c\/dd\u003e\n\u003cdt\u003eOEM Reference\u003c\/dt\u003e\n\u003cdd\u003e6E5-12411-30\u003c\/dd\u003e\n\u003cdt\u003eSupersedes\u003c\/dt\u003e\n\u003cdd\u003e688-12411-10 and 688-12411-11\u003c\/dd\u003e\n\u003c\/dl\u003e\n\u003c\/section\u003e\n\n\u003csection\u003e\n\u003ch2\u003eWhat's in the Box\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e1 x Thermostat\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThe thermostat housing gasket is not included. Replace the gasket during installation if the existing gasket is damaged, compressed or no longer seals correctly.\u003c\/p\u003e\n\u003c\/section\u003e\n\n\u003csection\u003e\n\u003ch2\u003eInstallation Notes\u003c\/h2\u003e\n\u003col\u003e\n\u003cli\u003eAllow the outboard engine to cool completely before beginning work.\u003c\/li\u003e\n\u003cli\u003eDisconnect the battery or otherwise follow the safety procedure specified in your engine service manual.\u003c\/li\u003e\n\u003cli\u003eLocate the thermostat housing and place a suitable container beneath the work area to catch residual water.\u003c\/li\u003e\n\u003cli\u003eRemove the housing cover carefully and note the position and orientation of the original thermostat.\u003c\/li\u003e\n\u003cli\u003eClean the housing and cover sealing surfaces. Remove old gasket material and inspect the surfaces for corrosion or damage.\u003c\/li\u003e\n\u003cli\u003eInstall the replacement thermostat in the same orientation as the original part. Follow the engine service manual for orientation details.\u003c\/li\u003e\n\u003cli\u003eInstall a suitable new gasket if required. The gasket is not included with this thermostat.\u003c\/li\u003e\n\u003cli\u003eReinstall the housing cover and tighten the fasteners to the manufacturer's specified torque.\u003c\/li\u003e\n\u003cli\u003eRun the engine using the correct water supply procedure for your outboard and check for leaks, proper water flow and abnormal temperature behavior.\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003cp\u003eUse the manufacturer's service manual for model-specific torque values, thermostat orientation and cooling-system procedures.\u003c\/p\u003e\n\u003c\/section\u003e\n\n\u003csection\u003e\n\u003ch2\u003eTroubleshooting \u0026amp; FAQ\u003c\/h2\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat does the thermostat do?\u003c\/summary\u003e\n\u003cp\u003eThe thermostat regulates coolant flow so the engine can operate within its intended temperature range. A thermostat that remains closed, remains open or operates inconsistently can affect engine temperature and cooling performance.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eIs the gasket included?\u003c\/summary\u003e\n\u003cp\u003eNo. This listing is for one thermostat. A thermostat housing gasket is not included and should be replaced separately when necessary.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eHow can I confirm compatibility?\u003c\/summary\u003e\n\u003cp\u003eCompare your complete Yamaha model designation and two-stroke or HPDI configuration with the compatibility table. Also compare the thermostat and housing against the original part before installation.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eCan I use this thermostat on another Yamaha model with the same horsepower?\u003c\/summary\u003e\n\u003cp\u003eNot automatically. Horsepower alone does not confirm fitment. Use the exact model designations listed above and verify the OEM reference before ordering.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat are common signs of a thermostat problem?\u003c\/summary\u003e\n\u003cp\u003ePossible symptoms include abnormal operating temperature, overheating, running excessively cool or unstable temperature behavior. Other cooling-system problems can cause similar symptoms, so inspect the complete cooling system before replacing parts.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003c\/section\u003e\n\n\u003csection\u003e\n\u003ch2\u003eSafety \u0026amp; Important Information\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eVerify the exact engine model, configuration and OEM reference before purchase.\u003c\/li\u003e\n\u003cli\u003eNever work on a hot engine or operate an outboard without the correct water supply.\u003c\/li\u003e\n\u003cli\u003eFollow the engine manufacturer's service instructions for installation, torque and testing.\u003c\/li\u003e\n\u003cli\u003eThis is a replacement part and is not represented as a Yamaha-branded OEM component.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/section\u003e\n\n\u003csection\u003e\n\u003ch2\u003eAbout Sea Sierra\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eMarine Replacement Parts\u003c\/strong\u003e — Practical service components for routine outboard maintenance and repair.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eApplication-Focused Listings\u003c\/strong\u003e — Compatibility information is presented by engine model and configuration where available.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eService Support\u003c\/strong\u003e — Verify fitment and installation requirements before ordering or beginning repairs.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/section\u003e\n\u003c\/section\u003e","brand":"SeaSierra","offers":[{"title":"Default Title","offer_id":50723781837115,"sku":"24TH504","price":26.4,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0826\/8673\/8747\/files\/Thermostat_for_YAMAHA_Two_Stroke_Outboard_6E5-12411-30_6E5-12411-20___6E5-12411-20_-_JLM_MARINE-8291431.jpg?v=1763031653"}],"url":"https:\/\/seasierra.com\/collections\/yamaha-2-stroke-outboard-marine-engine-parts-9-9-250hp.oembed","provider":"SeaSierra","version":"1.0","type":"link"}