Comments on: Motorcycle Air Pollution – part 3

By: Gaijin Bikers in Japan » Ride while you still can!

Gaijin Bikers in Japan » Ride while you still can! — Thu, 12 Jan 2006 12:53:33 +0000

[...] Tech holds other threats as well. While the Kneeslider has shown that the recent study claiming that bikes pollute more than cars was flawed, again it is only a matter of time before hybrid engines and other such technology make this true. When the day comes that motorcycles become less fuel efficient, more polluting, far more dangerous and far louder than cars, I fear that our days of riding free may be numbered. [...]

By: kneeslider

kneeslider — Fri, 06 Jan 2006 00:58:27 +0000

Common automotive technology such as fuel injection appeared much later in motorcycles, along with precise computer control of ignition throughout the rev range and differing engine load conditions. These two technologies alone would (I’m assuming here) make a substantial difference in combustion efficiency between earlier motorcycles and those being sold today. That is the reason I believe measuring today’s motorcycles is important before forming any conclusions. Early attempts at pollution controls on autos were not very effective either.

Their sample did reflect the traffic fleet they were dealing with but it is an historical study because when you consider remedies, what would they recommend? As I stated in my post, unless you are going to remove old motorcycles from the road or enforce the retrofitting of controls on those old motorcycles, all you would be mandating is the addition of controls to new models being manufactured today. But if you don’t know the level of pollutants contributed by the new models, you might be legislating an answer to a problem that doesn’t exist. Data about emissions from old motorcycles is interesting but not actionable.

I am not suggesting the new models are perfect or that we should pollute without a care, all I am saying is this study doesn’t tell us what we need to know before we act.

Just a point of clarification: I say the study is historical because you’re not dealing with a sample of current production motorcycles, even though the actual sample was a current reflection of the fleet on the road when the study was done. If any remedies implemented are to affect current models, not studying them is gathering historical data of past production.

By: palegreenhorse

palegreenhorse — Fri, 06 Jan 2006 00:25:57 +0000

I forgot to say that they specifically were looking at what they found to be a cross section of actual bikes on the road, not just new ones. they were trying to be realistic in their assessment, not historical.

By: palegreenhorse

palegreenhorse — Fri, 06 Jan 2006 00:23:13 +0000

Actually, I gathered two important things from the paper.
1. Two-wheeled vehicles, even when ignoring the contributions of the older mopeds and accounting for the difference in miles driven and the number of vehicles, contribute a disproportionate amount of polutants, excelpt CO2. See Figure 6 in the paper and the following quote.

“Whether in a direct comparison of mean unit emissions (in g/km), mean yearly emissions (in kg/vehicle/year), or fleet emissions (in tons/
year), the two-wheelers’ HC and CO emissions were all, and often significantly, higher. In addition, theNOx contribution of the motorcycle fleet is roughly one-fifth that of the car fleet and is thus not negligible.”

2. When emissions systems are implemented they don’t do a good job. Specifically the 1998 Honda VRF 800Fl(vehicle 7) and the 1999 BMW 1150GS(vehicle 8 ) should have lower emissions because they have an emissions system, but they don’t.

“However, the use of technologies similar to those employed in carsssuch as regulated three-way catalytic converters with fuel injection (vehicles 7 and 8 ) does not yield similar results either. It must be assumed that work on implementing the lambda control loop has not been performed with the same care as for cars.”

There are some arguments against this study being relevant in the US. Namely there are less two-wheeled vehicles per car in the US and the miles driven in the US on highway are much greater. However, I think smart motorcycle riders will come away from this saying just because we are small in number doesn’t mean we are insignificant. By motorcyclers taking a proactive stance regarding emissions of two-wheeled vehicles that should not be polluting–touring, commuting–we can preserve the ability to pollute while obtaining performance for the sport and dirt riders and the noise makers–harleys and custom bikes.