Are motorcycles green or smog machines? An examination of motorcycle emissions

August 4, 7:48 AMSF Motorcycle ExaminerJames Allgood

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High gas prices are causing motorcycle sales to skyrocket
and is bringing unwanted attention to motorcycle's dirty secret.

Motorcycles are incredible pieces of machinery. To me, their beauty comes from form following function. Their utilitarian design is perfect for moving a human or two from point A to point B. Minimalistic and with few frills, motorcycles are nothing more than an engine packed between two wheels. According to the L.A. Times motorcycles engines are extremely efficient – twice that of cars – at using gasoline to propel themselves but that efficiency comes with a cost.

Refined over a century and with few restrictions motorcycle engines have been designed to be small and lightweight while producing a lot of power. As a side effect they produce a lot of regulated emissions. There are three EPA regulated gasses emitted from internal combustion engines. Nitrogen oxides, hydrocarbons and carbon monoxide. The main reason these gasses are regulated is that they have a negative impact from a health safety standpoint. On top of the health aspects, the effects on the ecosystem and climate are becoming clearer too. Here are the problems with releasing large amounts of these gasses into the air:

• Nitrogen oxides (NOx) are tied to smog, as well as various repertory diseases like asthma, emphysema and bronchitis. When combined with sulfur dioxide from industrial use and power plants it produces acid rain, which can choke lakes and streams, reduce crop yields and eat away our infrastructure prematurely. Compared to cars and light trucks, motorcycles produce 4-10 times the amount per mile driven.
• Hydrocarbons (HC) are particles of unburnt fuel that are expelled in the exhaust. Similar to NOx, it is responsible for smog and repertory diseases. Typical motorcycles emit 2-5 times the amount that cars produce per mile driven.
• Last is carbon monoxide (CO). Odorless and invisible it can prevent oxygen from combining with the hemoglobin in your blood resulting in lack of energy and eventually suffocation. Fortunately motorcycles typically produce less – as low as a quarter – of CO as an automobile per mile driven.
• CO2, not regulated by the EPA but a known greenhouse gas is also as low as a quarter of what a car produces.

Today, motorcycle technology is not to the point where automobiles are when it comes to clean emissions. There are no PZEV (Partial Zero Emission Vehicle) motorcycles. Maybe the engineers have been focused on increasing power to weight ratios, maybe faster lap times have been preoccupying their time. But there are ways to make motorcycles cleaner. Charcoal canisters that recover gasoline vapors, three way catalytic converters and fuel injection – all available on a plenty of models – can have a huge impact on your emissions.

So how do these technologies affect your riding experience? As far as I can tell they don’t. Aesthetically they are a couple more pieces of equipment bolted to your frame. The weight is negligible, but the piece of mind that you are making the air a little cleaner for you and those around you should be worth it. There is no reason that motorcycles should not be as clean, if not cleaner, than cars. I suggest you demand that your next motorcycle have these items, otherwise there is no incentive for the manufacturers to innovate.