Upgrading the spark plugs in your Yamaha V MAX SHO 200HP, 225HP, 250HP or flashed 333HP outboard engine can improve ignition efficiency, throttle response, and engine longevity.
The stock ignition setup includes the Nickel electrode plug, which is a reliable option but requires more frequent 100 hour replacement.
One bolt-on upgrade is the Iridium electrode plug, which offers superior durability, enhanced combustion efficiency, and improved fuel economy.
Technical Comparison
The Stock NGK V MAX SHO Spark Plug (Nickel) is designed with a nickel alloy center electrode, measuring 2.5 mm in diameter, which requires a higher voltage to ignite the air-fuel mixture. This plug provides standard ignition performance but is more prone to carbon buildup over time.
In contrast, the Upgraded NGK V MAX SHO (Iridium) features a 0.6mm fine-wire iridium center electrode, allowing for more efficient combustion and lower voltage requirements. The iridium plug also offers greater durability, lasting approximately 200-300 hours compared to the nickel plug’s lifespan of around 100 hours.
Both plugs share the same heat range of 6 and a factory-set gap of 1.1mm (0.043 inches), ensuring compatibility with the Yamaha V MAX SHO engines.
Installation & Proper Gapping
Ensuring proper installation and spark plug gap is essential for maximizing performance. The required gap for both the nickel and iridium plugs is 1.1mm (0.043 inches), and it should always be verified using a feeler gauge before installation.
However, adjusting the gap on iridium plugs is not recommended, as the fine-wire electrode can be easily damaged, ensure the plug is delivered pre-gapped correctly.
- To install new spark plugs, start by removing the engine cover and locating the ignition coils.
- Disconnect the coil connectors and remove the coil packs using a 10mm socket.
- Next, carefully remove the old spark plugs with a 16mm (5/8”) spark plug socket and inspect them for wear.
- Before installing the new plugs, confirm the gap and, if desired, apply a small amount of anti-seize compound, to the threads to prevent seizing.
- Insert the spark plugs and tighten them to 12-14 ft-lbs of torque.
- Finally, reconnect the ignition coils, apply dielectric grease (Super Lube is available on this website) inside the coil boots, and restart the engine, allowing it to idle to confirm smooth operation.
Long-Term Maintenance & Cost Analysis
From a long-term maintenance perspective, the iridium upgrade offers a significant advantage. The Stock NGK V MAX SHO Spark Plug (Nickel) typically requires replacement after 100 hours of use, while the Upgraded NGK V MAX SHO (Iridium) can last up to 300 hours.
This extended lifespan results in fewer maintenance intervals and reduced overall costs. Although the iridium plugs cost more upfront, ranging from $12 to $18 per plug compared to the nickel plug’s $6 to $10, the long-term savings in replacement frequency make them a cost-effective choice.
Upgrading to iridium spark plugs not only reduces outboard maintenance but also enhances engine efficiency by providing consistent ignition and better fuel combustion.
The result is smoother acceleration, improved throttle response, and greater fuel economy, making the iridium one of the best upgrades for Yamaha V MAX SHO 200HP, 225HP, 250HP, or flashed 333HP outboard.
By following Yamaha's recommended maintenance schedule and ensuring proper installation, high performance boaters can maximize the performance and longevity of their outboard engines.
Includes six (6) Iridium IX Spark Plugs for Yamaha V MAX SHO Outboards
Please note, if your outboard is currently not running it's best or properly, inspect your spark plugs for wear, build-up, and the correct gap. Other ignition or fuel delivery issues could also be the cause of poor engine performance.
Contact Mike at 714-697-1716 or mike@buckshotracing77.com for technical support.