Stevens Instrument Company

About Stevens Instrument Company

For more than half a century, Stevens Instrument Company has been a trusted name among professional marine technicians, motorcycle mechanics, and small engine specialists. What began as Stevens Experimental — producing some of the earliest coil testers and magnet chargers purpose-built for marine applications — has grown into a third-generation, family-owned operation headquartered in Waukegan, Illinois. That heritage of hands-on craftsmanship and deep industry knowledge still drives every product the company makes today.

Stevens Instrument's longevity in a competitive market is no accident. The company's philosophy centers on building tools that last, and on maintaining the kind of long-term customer relationships that only come from consistently delivering on that promise. Professional technicians who rely on these tools day in and day out know that a Stevens instrument won't let them down mid-job — a reputation earned over decades of real-world use in marine dealerships, ATV shops, and outboard service centers across North America.

What Stevens Instrument Company Makes

Stevens Instrument specializes in a focused lineup of high-quality diagnostic and service tools designed for the specific demands of marine and powersports powertrains. Their products cover two critical areas of engine and drivetrain service:

• Spark Checkers: Stevens Instrument's spark checkers are widely regarded as industry-leading tools for verifying ignition performance on outboards, personal watercraft, and small engines. Models like the S-48 eight-wire spark checker support one to eight cylinders and are engineered from Valox — a material highly resistant to chemicals, UV exposure, and physical damage. Adjustable gap settings accommodate both standard and CDI ignition systems, making them versatile across a wide range of marine and powersports platforms.
• Gearcase Pressure Testers & Fillers: Proper gearcase maintenance is critical to the longevity of any outboard or sterndrive lower unit. Stevens Instrument's S-34 Gearcase Pressure Tester allows technicians to pressurize outboard and sterndrive gearcases and monitor for leakage — an essential step during lube changes and following any gearcase repair. Paired with their gearcase filler pumps and a comprehensive range of thread adaptors compatible with Mercury, Yamaha, Suzuki, Evinrude, and OMC applications, Stevens provides a complete solution for lower-unit service.

Built for the Professional Technician

Stevens Instrument tools are not designed for the casual weekend boater — they are engineered for the professional shop environment. Every product reflects the company's deep understanding of what marine and powersports technicians actually need: reliable readings, durable construction, and compatibility across the broad range of engines they service daily. Their broad range of testers covers both magneto ignition and CDI systems, giving shops a single trusted source for ignition diagnostic tooling regardless of the brand on the engine cover.

Whether you are servicing a high-horsepower offshore outboard, a jet ski, an ATV, or a small utility engine, Stevens Instrument Company offers the specialized tooling to get the job done right. Their commitment to quality and longevity — in both products and customer relationships — has made them a staple in professional marine service facilities for generations.