Is the Hand-Held, Two-Stroke Doomed?

Peter J. Marcucci
Special Contributor

The flexible and simplistic beauty of the two-stroke engine has enabled boaters, motorcyclists, snowmobilers and lumberjacks, to name a few, to accomplish many notable tasks over the last century.       

Patented in 1881 by Scottish engineer Dugland Clerk, the ever-evolving two-stroke has prevailed year after year as the power of choice for day-to-day work, play and competition. Having close ties to snowmobiling, motocross and MotoGP for many years, I’ve  witnessed some of this evolution firsthand.In the late 1960s, I watched this lightweight, air-cooled power plant dominate motocross and road racing by producing respectable power levels with only an expansion chamber exhaust. The 70s then saw the use of more radical porting combined with the reed-valve or in some instances, the rotary-valve. These innovations turned the simple two-stroke into a slightly more complicated, definitely more aggressive weapon—not for the timid or faint at heart. 

The quest for power didn’t end here, however, and eventually innovative research and development engineers designed the servo-controlled power-valve, turning a still relatively simple beauty into a vehement beast. These power-valve, liquid-cooled, two-strokes churned out horsepower at levels previously unattainable, allowing top riders to attain blistering record speeds and scorching their way into the American and European road racing history books. These engines continued to dominate for many years, until eventually giving way to the formidable four-stroke.

Over the last few years, many of us have heard the rumors that all two-strokes will be falling by the wayside because of the four-stroke. If you’ve browsed your local motorcycle or snowmobile shop lately, it’s easy to see how this thinking has gained credibility.

More and more manufacturers are migrating to the four-stroke engine in search of a high performance, cleaner burning and higher mileage power plant that can keep both sales and adrenaline flowing. Regrettably, it does appear that the two-stroke will be facing extinction in these venues in the near future.To find out if this migration to the four-stroke is also indicative that the trusty two-stroke concrete saw’s fate is also on the path to extinction, I met with Sarasota, FL local, Ki Mollison. While sitting comfortably in his showroom one morning, I asked Ki one simple question: What’s going on in the industry? He began by saying, “A lot of people are rumoring that small two-strokes are going to go away, but I don’t believe this.

It’s true that the EPA has gotten a lot more stringent on emissions for all two-stroke powered equipment including construction saws. For homeowners and commercial units alike, all manufacturers are being required to cut emissions. “It’s important to note that when the EPA evaluates the emissions of a manufacturer’s line of gas powered products, these products are looked at as a group, not individually. Emissions do differ between products, such as the emissions of a weed eater compared to a concrete saw. 

“So, when a manufacturer is asked to lower its emissions, that manufacturer does have the option to lower it in one tool and not in the other, thereby obtaining a combined reduction of emissions within the complete product line.” 

In addition to being the owner of Morse Equipment Company, Ki is also a longtime manufacturing-trend heavyweight in the gasoline powered equipment industry. He continued by sharing a few important facts with me: that Stihl and Husqvarna are the two major industrial concrete saw manufacturers, controlling about 70% of the market share in the industry, and that both manufacturers have to date, been very successful at creating a cleaner burning engine. Ki then went on to explain how the industry has conformed to the latest EPA emission goals.

“Stihl has come out with a design called the ‘Four-Mix,’ a two-stroke engine with a valve train. It’s a good design that burns very efficiently and is currently offered in some applications.

It is not available in industrial equipment yet, but may be introduced into more of their products in the future. “Husqvarna has gone a different way. They’ve created an optimized, scavenging combustion chamber that burns clean while still keeping the two-stroke engine simple. In my opinion, this is the direction I believe most manufacturers are going to take. “Husqvarna has also introduced a servo-controlled-electronic carburator that can adjust the air-to-fuel mixture 3,000 times per second.

To my knowledge, this is the most advanced technology to date. It is already available on their chainsaws, and I fully expect to see it on their concrete saws in the near future. Combine this with their scavenging system and you have a very clean burning engine. It’s really a neat technology!

You may also see some manufacturers adding catalytic converters, like on cars, to catch the carbon.” Ki then went on to explain that the four-stroke is gaining in popularity, but as far as being efficient in smaller industrial applications, its use is just not feasible at this point. When asked why, he said, “You cannot get the power to weight ratio needed in a handheld, four-stroke work tool at this point. A power tool like a chainsaw or concrete saw needs to be both powerful and light. 

“Weight is very important. Motorcycles and snowmobiles aren’t that critical for weight, and these engines have a different set of design dynamics that come into play. A concrete saw is spinning at 10,000 to 25,000 RPM at the blade, and it’s very hard to achieve this level of performance. 

“No one has figured out how to develop a four-stroke that is equal in weight with the same amount of torque as a two-stroke for this application. You would have to almost double the weight of the tool!” He continues, “I don’t see four-strokes coming anytime soon to the industrial tool market.

I do believe, however, that you will see leading manufacturers continue to develop new technology that will keep the two-stroke viable for many years to come. New standards come out about every four years, and manufacturers will continue to keep up with those EPA standards for the foreseeable future by developing cleaner burning engines.

”When asked if OSHA has requested the reduction of dB levels in gas powered industrial tools, Ki said, “I don’t know of any dB restrictions from OSHA—two-strokes need to breathe! If they can’t breathe, they can’t burn clean!“What I have seen that may pertain to OSHA is that Stihl has come out with a variable water flow system that lets water flow proportionately to the blade RPM when you’re cutting concrete or blocks with a diamond blade.

When used, this feature should help reduce dust at a job site.” When asked for the down-side of these innovations, he simply remarked, “These new technologies are going to make it more difficult on the service side. Some service shops are going to have a hard time keeping up with these designs, and this will definitely increase the servicing costs to the user.

It will also make the initial purchase of these power units more expensive.” So, with the ever-developing four-stroke looming on the horizon, is our beloved two-stroke construction saw doomed to extinction? I think not—at least not anytime soon. The flexible and versatile two-stroke has always risen to the occasion. Today’s two strokes, pound for pound, are still a handful of simple, lightweight, reliable power.

I am, however, reminded of the lightweight, heart-stopping power that manufacturers have achieved every time I twist-the-wrist on my four-stroke motocross or sport bike. 

Peter Marcucci is a 25-year senior fabricator at European Marble Co., Inc. Sarasota, FL. Send any comments to pjmgsxr@aol.com.