Just a little note to add on the scooter’s two stroke emissions. Since the combustion is typically colder on a two stroke engine, they produce a lot less NOx than a four stroker. Typically that is one reason why there is no specific NOx regulation for this class of vehicles.
They do spew out a whole lot more HC but slightly less CO2 per km…
HTH
Another comment - not all scooters are two-strokes. A quick perusal of Vespa’s USA site (http://www.vespausa.com/scooters.php) in fact produces no two-strokes on offer. It’s a lot easier to make a 4 stroke engine burn cleanly than it is a two stroke, one factor which has lead to the near demise of the 2 stroke in two-wheeled usage in general. I think it’s unlikely that these newer scooters are near the legal limits for emissions, although my quick look didn’t reveal any actual numbers.
To expand on the OP, CO and NOx are related for most combustion sources. Cold temperatures increase CO while hotter temperatures increase NOx. You’ll never eliminate both from the combustion source, but you can reduce them in the exhaust with equipment like a catalytic converter.
Here is a link to the column in question: What’s better for the environment, a scooter or a car? - The Straight Dope
… and finally, I’d say that CO (carbon monoxide) is not really much of a concern these days, at least for the wider world. There might be enough to worry about if the exhaust is in an enclosed space (closed garage, or leaking into the passenger compartment) but there’s not really enough CO to affect the general atmosphere at this point.
I’ve heard someone making a speech where they wanted to make the point that environmental regulation has had successes. One example was that the Hemlock Society (dedicated to helping people commit suicide) no longer recommended the ‘running car in a garage’ method, because newer cars were too clean to rely on the CO killing you quickly enough.
Exactly!
When I was reading the columns, I kept wondering whether the next paragraph would make the point that the “green friend” was probably riding a very old scooter (1970s?), and that nowadays, four-stroke scooters are much, much cleaner and much, much more prevalent.
But that paragraph never came. So, either the point was lost on Cecil, or he for some reason only applied his answer to the specific situation asked about (which is only *somewhat *justifiable IMHO).
But really, all it would take is a sentence or two to alert readers that the situation described (a two-stroke engine on a scooter) is very rare these days. (At least in the First World – I hear that SE Asia is brimming with two-stroke scooters.)
And from a noise pollution standpoint four-stroke engines are a whole lot quieter.
Yeah, but most of the cheap Chinese scooters people buy these days are 2-strokes. The nice Hondas and Vespas are thousands of dollars more.
And then converts them into the latest legislated evil: CO2…
But CO will eventually combine with atmospheric oxygen to form CO[sub]2[/sub] anyway. The catalytic converter just speeds up the process.
One thing I noticed was that Cecil talks about emmissions per mile. In city traffic, Id say that would be a hard comparision to make properly. The scooter, or any other bike, and the SUV might both cover the same distance on the trip to work, but the SUV will take a lot longer and its engine will be running all that time. It would be interesting to see how the shorter trip-time for scooters swung the balance back.
I worked for a while riding a 150cc scooter for a delivery firm, and I can clearly reacall that at times of the day when traffic was heavy, I could be out and back from a journey of several miles before one of the van drivers could get half a mile, so the difference isn’t small.
A motorcycle magazine tried to cover the same distance (mixed highway and city commute) with a Yamaha XT and a Toyota Prius. Surprisingly, the motorcycle did only marginally better consumption-wise (I believe it was 5.5lt/100km for the motorcycle versus 6.0 for the car) but it covered the distance in 1/3 of the time.
About 2-stroke engines: It looks like 4 stroke engines are gaining ground even in specialty motorcycles (enduro, motocross) where 2 stroke once dominated. Nowadays KTM, Husaberg and Husqvarna offer very few 2 stroke models. IMO it is because the gap between 2 and 4 stroke engines in terms of weight and power (the main advantages of 2 stroke) has narrowed significantly over the years.
My cheap Chinese sooter is 4-stroke.
He also missed the fact that production of NOX is unique among pollutants. If the fuel mixture in the cylinder is richer than 14.7:1 there is little to no NOX produced. If the mixture is leaner than 14.7:1 at a steady state cruise, lots of NOX is produced.
This is why that pre 1968 NOX was not considered a pollutant. As the non pollution controlled cars ran rich, little to no NOX was produced. When exhaust controls came into existence with the 1968 model year now cars ran lean at cruise and started spewing NOX. This is what lead to the add on NOX devices that California required on some cars back in the 1970s.
This is exactly why per-mile is the right comparison to make. If I have to get from home to my job 17 miles away, then I’m going to be traveling 17 miles, no matter what vehicle I use. So the question is, which one produces less pollutants in that 17 miles? If one engine or the other has to run for a shorter time to get that distance, then that’s going to be taken into account in the pollution per mile.
Not a typo?
There are new Electric Scooters that emit no fumes and are silent too. example is the e-Go. Really reduce pollution in city.
Sorry you misread me. I meant that a scooter or bike in city traffic will take considerably less time for the same trip and its engine will also be running for less time. And believe me, I know from experience that in rush-hour traffic, the difference in trip times is large.
All the time a car is stuck in traffic, making sometimes a few yards per minute, it’s still pumping pumping out exhaust fumes. A 2-stroke scooter may pump more out, but for less time. I was wondering how much the shorter running-time made up for the worse emissions.
Just curious, what brand? What did you pay for it?
Kymco People 150. I think it was $2,995 when I bought it last summer. I like it a lot; enough power to easily haul my 225 lb ass around. I’m not sure I’d recommend it to some more than 5’10" or so, or with big feet, but it is plenty big enough for me. I’ve had it up to 65MPH, but above 60 the front end seems a little loose.