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The Kohler 5400 Series engines are smaller and lighter than the Courage line they replace. (all images: Kohler)

Kohler engineers new 5400 engines for lower NVH, easier start-ups

For lawn tractor applications, easy-starting and smooth-operating engines are key to user satisfaction. Wisconsin-based engine and power systems manufacturer Kohler has announced an all-new 5400 Series engine line purpose-built to address these mower ergonomic attributes. The single-cylinder, OHV engine line includes models from 17 to 19.5 hp (12.7 to 14.5 kW) and includes brand-new features for the riding lawn-equipment market.

“When it comes to lawn tractors, users want an engine that’s easy to start, smooth running, simple to maintain and built to last. Our new 5400 Series more than delivers by incorporating a variety of user-friendly advancements,” said Brett Wegner, product manager for Kohler Engines. “When developing this line, we applied our expertise from Kohler’s robust twin-cylinder engines to design in many durable features and user benefits. Without question, the 5400 Series takes our single-cylinder offering for ride-on mowers to the next level.”

The Kohler 5400 Series replaces the aging Courage engine line. Despite all the new features on the engines, the 5400 Series did not grow in size or weight. Displacement was reduced from 597 cc to 541 cc, but net torque increased for each engine. The height and width decreased approximately 1.5 in (3.81 cm) and 1 in (2.54 cm), respectively. Kohler also trimmed the weight down to 75 lb (34 kg) from the 79-lb (36-kg) Courage engines.

The first new feature for the 5400 Series is a Triple-Balance System, which is specifically designed to reduce vibration and engine noise. Kohler tested nearly a dozen balance-system design variations before deciding on the new system. It features a dynamically balanced crankshaft and dual counter-rotating cast iron balance gears. These three weight-balance components are what enable the low engine vibration and noise.

According to Eric Hudak, marketing manager for Kohler Engines, this was the most challenging aspect of developing the new single-cylinder engine line. “Every engine program has its challenges. In the case of the 5400 Series, our upfront investment into developing the ideal balance system for the engine was the most significant challenge,” he told Truck & Off-Highway Engineering. “But, the feel of the reduced vibration when you sit on the product makes all that investment worth it.”

Another new user-focused feature is Kohler’s Smart-Choke Technology, which removes the need to prime or choke the engine. The fuel system is designed to add just the right amount of fuel during starting, even during cold starts at below freezing temperatures. The choke is opened approximately 50% during starting and then opens the remaining choke during the first 30 seconds of operation. This technology was first released on the 7000 Series engines in 2014 and has proven its reliability.

Kohler also incorporated other technologies developed from its larger twin-cylinder engines for the new single-cylinder 5400 Series. Consistent-Cut Technology uses back-up torque and a low governor droop to maintain the engine speed during high-load conditions for a cleaner cut. From a service-aspect, an inverted oil filter allows for dripless oil changes. Advanced cooling technology allows for lower engine operating temperatures, increasing mower uptime.

“We believe this line will be an appealing new option for today’s technology-driven lawn tractor users,” added Wegner. “But, it also represents an opportunity for outdoor power equipment dealers who have been seeking a new engine in this horsepower range designed from the ground up around the needs of their customers.”

Kohler is backing the new engine after over 20,000 hours of testing with a comprehensive three-year warranty. The new 5400 Series was engineered in Kohler, WI, and will be manufactured at the company’s production facility in Hattiesburg, MS.

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