NGK DR4HS SPARK PLUG

Function and technical context

The NGK DR4HS spark plug is part of the outboard engine's ignition system, being responsible for generating the electric spark that ignites the air-fuel mixture in the combustion chamber at the precise moment in the engine cycle. Its correct operation is essential to guarantee efficient combustion and optimal acceleration response. A worn electrode or an incorrect gap causes misfires, notable loss of power and increased fuel consumption. In two-stroke engines, where each cycle requires a reliable spark, the quality of the spark plug has a direct impact on the reliability of the boat on the water.

When to replace this part?

The most common symptoms of a bad spark plug include difficulty starting the engine when cold, pulling or cutting during low-load cruising, unstable idling, and excessive smoke from the exhaust. In outboard engines, it is recommended to check and replace the spark plugs every season or every 100 hours of use, whichever comes first, since the marine environment—with its variations in temperature and humidity—accelerates the deterioration of the electrode and the insulator. Changing the spark plug preventively before each season is one of the most economical and effective maintenance interventions to avoid unexpected breakdowns while sailing.

Compatibility