YAMAHA 6K700 Heads 225

( Manufacturer Part Number: 6K700 ), ( Part Type: Head ), ( Country Of Origin: United States )

Review YAMAHA 225 Heads fits EXCEL 1987

The **Yamaha 6K700 1987 Excel 225 Head** is a legendary, high-performance marine outboard engine that stands as a testament to Yamaha s engineering prowess of the late 1980s. Built with precision and designed for both reliability and raw power, this 700 cubic-inch (11.5-liter) two-stroke inline-six cylinder marvel was a staple in professional fishing, offshore cruising, and high-speed applications during its era. The **Excel 225 Head** designation refers to its advanced cylinder head design, featuring a unique **225-degree combustion chamber** that optimized fuel-air mixture distribution, improving efficiency and reducing emissions compared to earlier models. This engine was originally paired with Yamaha s legendary **6K700F** or **6K700M** variants, delivering an impressive **225 horsepower** at the crankshaft though after the gearbox, it translated to a robust **180 200 horsepower** at the propeller, making it a force to be reckoned with on the water. The **1987 model year** represents a refined iteration of the 6K700 series, incorporating updates to the fuel injection system, exhaust manifolding, and cooling efficiency, all while maintaining the engine s signature durability and torque.

Mechanically, the **6K700 Excel 225 Head** is a masterclass in marine engineering, featuring a **cast-iron cylinder block** with precision-bored bores and **forged steel crankshaft** supported by seven main bearings for exceptional durability. The **dry-sump lubrication system** ensures consistent oil flow even under extreme angles or high loads, a critical feature for offshore and deep-sea applications. The **fuel-injected** design (with optional carbureted variants) provided precise metering, reducing vapor lock and improving throttle response an innovation that set Yamaha apart from competitors in the late '80s. The **exhaust system** was designed with a **twin-outlet configuration**, reducing backpressure and enhancing performance, while the **water-cooled cylinder heads** prevented overheating even during prolonged operation. The **gearbox** was a robust, multi-stage unit with a **direct-drive or gear-reduction option**, allowing for optimal propeller selection based on vessel size and intended use.

One of the most striking features of the **1987 Excel 225 Head** is its **build quality**, which reflects Yamaha s commitment to longevity. The engine was constructed with **heavy-duty components**, including **pressure-lubricated rod bearings**, **hypoid gears** in the gearbox, and a **sealed, corrosion-resistant** design that could withstand the harshest marine environments. The **fuel injection system** (when equipped) was a significant upgrade over carburetors, offering better fuel economy and smoother operation, while the **electronic ignition** provided consistent spark timing for reliable starts and power delivery. The **cooling system** was a closed-loop design with a **thermostatically controlled** water pump, ensuring optimal operating temperatures even in demanding conditions.

Beyond its mechanical strengths, the **Yamaha 6K700 Excel 225 Head** was a favorite among professional anglers and offshore adventurers for its **reliability and adaptability**. It was commonly paired with **center consoles, offshore fishing boats, and high-speed cruisers**, where its **torque and endurance** were invaluable. The **225-degree combustion chamber** not only improved combustion efficiency but also contributed to a **smoother power delivery**, reducing vibration and wear on the drivetrain. While modern marine engines have evolved with electronic fuel injection, turbocharging, and stricter emissions regulations, the **1987 6K700 Excel 225 Head** remains a sought-after piece for collectors, restorers, and enthusiasts who appreciate its raw power, timeless design, and the unmatched performance it delivered in its prime.

For those looking to restore or maintain this engine, the **6K700 Excel 225 Head** offers a rewarding challenge. Yamaha s **OEM parts availability** (through authorized dealers and aftermarket suppliers) ensures that most components are still accessible, though some specialized items may require sourcing from vintage marine parts specialists. The engine s **modular design** allows for upgrades, such as **high-performance cylinder heads, upgraded gearboxes, or modernized fuel systems**, making it possible to breathe new life into a classic while preserving its original character. Whether used in a **restomod project, a classic offshore rig, or as a centerpiece in a marine engine collection**, the **Yamaha 6K700 1987 Excel 225 Head** embodies the golden age of marine propulsion a blend of brute force, engineering brilliance, and unmatched presence on the water.

### Yamaha 6K700 (1987 Excel 225 Heads) Pros and Cons

1. **Reliability and Durability** The 6K700 is a well-regarded marine diesel engine known for its robust construction and longevity. Many units from the late 1980s have lasted decades with proper maintenance, making it a solid long-term investment for those who prioritize durability over modern conveniences.

2. **Proven Performance** This engine was designed for heavy-duty use, including fishing boats, workboats, and larger recreational vessels. It delivers strong torque and consistent power, making it suitable for demanding applications. The 225 HP rating ensures it can handle significant loads, whether towing, cruising, or operating heavy equipment.

3. **Availability of Parts and Service Support** As a Yamaha classic, the 6K700 has a strong aftermarket presence. Parts like pistons, rods, bearings, and gaskets are widely available, and many marine mechanics are familiar with its service requirements. This reduces the risk of being stranded due to part shortages.

4. **Fuel Efficiency for Its Class** Compared to modern outboards of similar power, the 6K700 is relatively fuel-efficient for its era. While it won t match the MPG of a modern turbocharged engine, it consumes fuel at a reasonable rate for its size and power output, which can be cost-effective for frequent use.

5. **Lower Operating Costs (Compared to New Engines)** The initial purchase price of a used 6K700 will be significantly lower than a new outboard of comparable power. Additionally, maintenance costs (though not negligible) are often lower than those of newer, more complex engines with electronic fuel injection, turbocharging, or advanced diagnostics.

6. **Classic Yamaha Build Quality** Yamaha s reputation for precision engineering and attention to detail in the 1980s is well-earned. The 6K700 features a cast-iron block, forged crankshaft, and a robust cooling system, all of which contribute to its reputation for reliability when maintained properly.

7. **Resale Value and Collectibility** For enthusiasts or those who appreciate classic marine engines, a well-maintained 6K700 can hold its value better than many modern outboards, especially if it has a clean service history. Some buyers may also view it as a statement piece or a nostalgic choice.

8. **Simplicity of Design** The 6K700 uses a carbureted or early fuel-injection system (depending on the model year) that is easier to diagnose and repair than modern electronic systems. This can be an advantage for DIY mechanics who prefer mechanical simplicity.

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1. **Age-Related Wear and Potential Hidden Issues** A 1987 engine is approaching 40 years old, which means it has likely accumulated significant mileage (or hours of use). Common wear points include the crankshaft bearings, camshaft bearings, pistons, and cylinder walls. A thorough pre-purchase inspection is critical to avoid costly repairs down the line.

2. **Maintenance Requirements** The 6K700 demands regular and meticulous maintenance to remain reliable. This includes frequent oil changes (with high-quality marine diesel oil), cooling system flushes, fuel system cleaning, and inspection of critical components like timing belts, water pumps, and seals. Neglecting maintenance can lead to catastrophic failure.

3. **Emissions and Environmental Regulations** Older diesel engines like the 6K700 do not meet modern emissions standards (e.g., EPA Tier 4 or EU Stage V). While this may not affect personal use on private waterways, it could limit operation in certain marinas, lakes, or coastal areas with strict environmental regulations. Some states or countries may require retrofitting with emissions control devices, adding to the cost.

4. **Fuel System Challenges** The 6K700 may use a carbureted or early fuel-injection system that is less efficient and more prone to clogging than modern systems. Fuel quality (especially diesel with sulfur or contaminants) can accelerate wear on injectors, pumps, and filters. Some owners report issues with fuel starvation or inconsistent performance if the system isn t properly maintained.

5. **Noise and Vibration** Older marine diesels can be louder and vibrate more than modern outboards, which often incorporate sound-dampening materials and smoother-running components. This may not be an issue for all users but could be a consideration for those sensitive to noise or seeking a quieter ride.

- Electronic fuel injection (EFI) for precise fuel delivery.

- Turbocharging or supercharging for increased power output.

- Advanced diagnostics or onboard computer systems for troubleshooting.

- Modern cooling systems (e.g., closed-loop cooling) that reduce corrosion and maintenance.

- Quiet operation and vibration reduction technologies.

7. **Higher Repair Costs for Major Components** While parts are available, labor costs for major overhauls (e.g., crankshaft replacement, block machining) can be significant. Some components may require specialized machining or reconditioning, adding to the expense.

8. **Compatibility with Modern Boats** If the engine is being installed on a newer boat, there may be compatibility issues with wiring, control systems, or mounting interfaces. Retrofitting may require additional modifications or custom work.

9. **Resale Market Limitations** While the 6K700 has a dedicated following, it may not appeal to the broader market of buyers looking for modern, low-maintenance engines. This could limit resale options if you decide to upgrade later.

10. **Potential for Corrosion** If the engine has been stored improperly or exposed to saltwater without adequate protection, corrosion could have damaged internal components (e.g., cylinder bores, exhaust manifolds, or cooling passages). A thorough inspection is essential to assess this risk.

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The Yamaha 6K700 (1987 Excel 225 Heads) is a **strong, reliable, and powerful** marine diesel engine that remains a favorite among enthusiasts and those who prioritize durability and performance over modern conveniences. It is well-suited for owners who:

- Are prepared for regular maintenance and potential repairs.

- Value a proven, heavy-duty engine for fishing, workboats, or classic vessel restoration.

- Have access to mechanical skills or a trusted marine mechanic.

- Are not concerned about emissions regulations or noise levels.

- Appreciate the nostalgia and craftsmanship of a classic Yamaha.

- Seek a low-maintenance, plug-and-play engine with minimal upkeep.

- Plan to operate in areas with strict emissions regulations without retrofitting.

- Want the latest in fuel efficiency, power output, or technological features.

- Are on a tight budget for repairs or overhauls.

- Prefer the quiet, smooth operation of modern outboards.

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1. **Thorough Pre-Purchase Inspection** Have a **marine diesel specialist** perform a complete teardown or at least a compression test, leak-down test, and inspection of critical components (crankshaft, bearings, pistons, cylinder walls, fuel system, cooling system). Look for signs of excessive wear, corrosion, or damage.

2. **Service History** Request a detailed service history, including records of oil changes, timing belt replacements, fuel system cleanings, and any major repairs. A well-documented history is a strong indicator of the engine s condition.

3. **Test Run** Conduct a **road test** (or water test, if possible) to evaluate performance, noise levels, vibration, and any unusual exhaust smoke (blue smoke indicates oil burning; white smoke could signal coolant leakage).

- **Crankshaft and main bearings** (if worn).

- **Camshaft and lifters** (if noisy or sluggish).

- **Cylinder wall resurfacing or piston replacement** (if compression is low).

- **Fuel injection system cleaning or replacement** (if misfiring or poor performance).

- **Cooling system overhaul** (water pump, impeller, seals, and corrosion protection).

5. **Consider a Rebuild or Reconditioning** If the inspection reveals significant wear, weigh the cost of a **full rebuild** by a reputable marine engine shop. A professionally rebuilt 6K700 can often be more reliable than a used unit with unknown history.

- Is this engine the best fit for your boat and intended use?

- Are you comfortable with the maintenance demands?

- Could a modern outboard (e.g., Yamaha F200, Mercury Verado, or Suzuki DF250) meet your needs with lower long-term costs?

7. **Negotiate Price Based on Condition** If the engine is in **excellent condition with a clean service history**, it may be worth the premium. If it requires **major work**, factor those costs into the purchase price or walk away if the total cost of ownership is prohibitive.

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Details:

One is in good working condition. This is for the set. 1987 Yamaha Excel 225 heads. The other has scarring as pointed out in the pic with my finger pointing to it.

part #: 6k700 price

• $200.00

specifications propboapar:

• for models: Excel
• for makes: Yamaha
• for years: 1987
• mpn: 6k700
• part type: Head
• country of origin: United States

shipping propboapar:

• class: Standard
• carrier: USPS
• transit: 6-12 Days
• cost: $0.00
• service: USPS Ground Advantage
• type: Calculated

general propboapar:

• Parts Accessories > Boat Parts > Propellers
• condition: Used

seller propboapar:

• # reviews: 95
• rating: 100.0%
• city: Shawano, Wisconsin

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• policy: No Returns

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• options: Ship-to-home
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• sold: 0
• availability: In Stock
• started: February 16, 2026
• quantity: 1

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