You might think any spark plug will work. Wrong. The Suzuki DT4 owners manual specifies:

Maintaining a 2-stroke outboard motor (produced roughly between 1985 and 1998 ) requires a systematic approach to care. Whether you are a professional mechanic or a DIY boat owner, the owner's and service manuals provide the essential technical roadmap for everything from break-in procedures to advanced engine overhauls. Essential Specifications Suzuki DT4

Official manuals are available through various specialized platforms: Suzuki DT4 (S) - Hallberg-Rassy Club

If water isn't flowing from the "pee hole," stop the engine immediately. Debris in the water intake or a degraded impeller are the most common culprits. Where to Find Manuals

In an age of digital fuel injection and onboard computers, it is easy to forget that older engines like the DT4 are purely mechanical. Every function—from the flow of fuel to the spark timing—is controlled by cables, carburetors, and linkages. The Suzuki DT4 owners manual isn't just a "quick start guide"; it is the blueprint for the engine’s soul.