[Honda100]

I didn't run through the whole post, but I do have a wide variety of scooters and motorcycles. Also keep in mind that all of my mpg figures are very accurate as I use a measuring pitcher to add fuel to my bikes and top them off to the very brim (which you can do on a bike like a Super Cub or Metropolitan 50).

Anyway, my observations are this. Japanese fuel economy numbers are based on a cruising speed of 18 mph, which of course you just can't do. My Metropolitan (called the Crea Scoopy in Japan) is rated at 71 km per liter or 167 mpg in carb form, and 78 km/l in FI form. Now at 18 mph my Metro runs at roughly 4500 rpm and 1/4 throttle. At 30 mph it's at 7000 rpm, and at 40 (where you need to be most of the time on "normal" roads), it's at 8200 rpm and hitting the redline. So little wonder I "only" get 97 mpg. Also to note, scooters are geared for acceleration and speed, so instead of being able to take advantage of better fuel economy, you're constantly over 4-5k rpm so that you can keep up with traffic and no be run over.

Now my Super Cub 100 is geared a lot taller, and even at 40 mph it's doing a smidge under 5000 rpm. At that speed I get about 130 mpg. However, if I drop that speed to 20 mph like the Japanese ratings suggest, I am well over 250 mpg and even managed 320 on one tank. US mpg. At 20 mph and tall gears, it runs at 2200 rpm in top gear, and if you can imagine a 102cc motor at 2200 rpm, it's really nothing.

Then take my Wave 125, it has 4 speeds vs. 3 and is geared even taller so that at 20 mph it's around 1500 rpm or just above idle. Again, you can manage 200 plus mpg on it at that speed, but of course when you need to keep it at 1/2 throttle or above, you're down to 120-130 mpg again.

Anyway, I guess my point is is that cars are a lot easier to predict because they are driven in roughly the same circumstances and throttle ranges most of the time. No one can keep their foot glue to the floor for obvious reasons, so it's all 20-30% throttle most of the time, where as motorcycles and scooters need to be flogged to match speeds on road with the cars they are surrounded with. Also, remember motorcycles have the aerodynamic properties of a parachute so the faster you go, a MASSIVE decrease in fuel economy takes place.


Also, in the real world, I've found that my FI bikes (the Wave is fuel injected) isn't really that much better than the carbed ones for fuel economy. I think it's down to them being air cooled and run a tad on the rich side. Also, the fuel injected Metro (Crea Scoopy) even though it's water cooled, does noticeably worse than my carbed 02 Metro for reasons I don't understand. The 02 would do 100 plus mpg all the time whereas I am lucky to break 100 with the FI one.