Fire up your Yamaha on the first twist of the key with Champion RA8HC Spark Plugs (810 | 10388)—a drop-in upgrade that keeps two-stroke and small four-stroke outboards lighting clean and strong. Champion pairs a copper-core center electrode with a nickel-alloy ground strap, pulling heat away from the tip so it resists fouling at long trolling speeds yet stays hot enough for quick holeshots.

Cut to a 12 mm thread with a 5/8-inch (16 mm) hex, the RA8HC screws straight into many Yamaha 40–60 HP classics and portable models without adapters. A factory-set 0.028-inch gap and built-in resistor tame radio noise that can scramble your GPS or digital tach, while corrugated ribs on the porcelain insulator stop flash-over in damp weather.

Why these plugs earn space in your spares box

• Cooler, cleaner burn: copper core sheds heat for longer life and steadier idle.

• Marine-ready build: nickel electrodes shrug off salt and leaded fuel additives.

• Plug-and-play fit: 12 mm threads, gasket seat, and removable nut match Yamaha specs.

• Reliable spark every cycle: resistor design protects sensitive electronics from RFI.

Swap them in during your annual service and enjoy crisp starts, smoother throttle response, and confidence that every cylinder is firing exactly when it should.