Quote:
Originally Posted by prodigit
Yeah, fuel injection injects fuel and air into the cylinder causing a slight overpressure, as opposed to a carb version, where the cylinder due to a vacuum sucks the fuel/air mixture in.
This effect you have with fuel injection is similar to the effect of a mild turbo; especially noticeable in the low end.
It's like having the power of a 66cc kit with having only a 49cc cylinder.
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The fuel is injected under high pressure in a fog like spray. The air is pulled through the throttle body by the vacuum from the piston, same as a carb set up. No turbo charged effect.
Fuel injection is better at metering a more precise fuel mixture, therefore by design allowing more efficient combustion which usually means better performance/fuel economy. Unfortunately most fuel injected motorcycles/scooters are set up borderline lean to pass emissions. This often negates the performance advantages of fuel injection over a well tuned carburetor, but fuel economy is usually better. Scooters with carbs are often set up with the same lean conditions, but it is a simple matter of rejetting to get optimum performance. Not always so easy to do with fuel injection.
To get back on topic, I've owned about 10 scooters, not counting another 10 or so motorcycles.