There's been some published research on this, and they generally agree with mythbusters. From the abstract:
----------- Even though the motorcycle, fleet is small in comparison with the car fleet, and logs lower yearly mileage per vehicle, their contribution to traffic emissions has become disproportionately high. Exhaust emissions of CO, HC, NOx, and CO2 from 8 powered two-wheelers were measured and compared to previous measurements from 17 gasoline-powered passenger cars performed at EMPA with the aim of ascertaining their relevance. Using exhaust emission ratios from both vehicle types, comparisons based on mean unit, mean yearly, and fleet emissions are considered. Present-day aftertreatment technologies for motorcycles are not as efficient as those for cars. A comparison of mean unit emissions shows that motorcycles exceed cars in NOx emissions. All comparisons reveal a significant HC ratio, to the detriment of two-wheelers. Overall, the relevance of emissions from powered two-wheelers is not negligible when compared with modern gasoline-powered passenger cars. ----------- Here's the listing. I don't have access to the full article. http://trid.trb.org/view/2006/C/782272 Noah On Mon, Oct 10, 2011 at 11:39 PM, Pat Patterson <[email protected]> wrote: > Bikes have all sorts of problems that cars simply don't. First up exhaust > length. I notice this between side dump exhaust and bumper exit on my > pickup. I'm not sure how big the cat is on a bike But I know it's not enough > for a 3way + 2 way 2 cat setup that you'd find on a new mustang. Cylinder > temps, air cooled is obviously impossible to control to the degree that a > car can but with it's exposed cylinders and minimal mass even a water cooled > bike is going to vary more than a car. > > Driving style and transmissions. The cars I'm sure were all auto's and I > highly doubt the bikes were. A 250cc bike will be working far higher into > it's % of power available than the car will be, I'm no expert but I'm sure > that has an effect on emissions. > > As you stated their methodology is often suspect. > > > At 07:13 AM 10/6/2011, you wrote: > > If you compare a car and a bike with similar emission control devices, and > you still get that the bike pollute more, that I don't understand. I don't > think cars and bikes are that different in terms of the mechanics. I am very > suspicious about these results. In general, I like the program as > entertainment, but they don't really follow a good scientific methodology. > It is always better for them to do the experiment and get an unexpected > results than otherwise. > > Javier. > > On Thu, Oct 6, 2011 at 2:10 AM, surfswab <[email protected]> wrote: > But they're driven less, there are fewer of them and they produce more > smiles per mile, and that works for me. (!) > > Pat Patterson > Abbotsford, BC, Canada > > > 2001 PT Cruiser > 83 450 Honda Nighthawk > 78 F350 460/C6 on propane > 71 Bronco 302/C4/D20 D44/9" > > > Some people try to turn back their odometers. Not me, I want people to know > "why" I look this way. I've traveled a long way and some of the roads > weren't paved. > > "If you can't take the heat, don't tickle the dragon." > > > > > > > > > > > > > -- > You received this message because you are subscribed to the Google Groups > "Nighthawk Motorcycle Lovers!" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/nighthawk_lovers?hl=en. > -- You received this message because you are subscribed to the Google Groups "Nighthawk Motorcycle Lovers!" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/nighthawk_lovers?hl=en.
