thanks stickman. glad i listened to these guys and started learning on the ex500.
alanheng, thanks for the link, but it doesn't help someone with my limited knowledge much.
so it seems carb has been around forever, and can be adjusted. what does "jetting" do?
and it seems FI is jerky, but is supposed to control the O2, gas mixture, better?
anyone able to explain the technical differences in more detail to a newbie?
"jetting" refers to replacing the stock jets and needles with "performance" ones. The new ones are usually more adjustable than the stock ones, so you can get a better setting.
Carbs and FI both do the exact same things. They atomize fuel, and mix it with incoming air. How much AIR is added is controlled by the throttle position. How much FUEL is added depends on the carb or fuel injection computer.
Fuel injection systems have sensors that determine throttle position, vacuum, air temp, exahust O2 content, and any number of other factors. You feed all of this info into the computer. Using this information, they can adjust how much fuel is added to the air to give you the best performance. FI systems can adjust much better to different air temps, altitudes, fuels, etc..A good example is that a FI bike will usually start better in cold weather than a carb bike.
Carbs do all of the same stuff, but they are all mechanical. They are directly controlled by the vacuum in the intake. The vacuum pulls air past a venturi, which is used to pull fuel into the intake, and atomize it. The jets and needles control how much fuel you get for a given amount of air flow. (i.e., a given throttle position) Since they can't really sense ALL of the factors, they can't always adjust very well to changing air temps, altitudes, etc.
Now, in MOST cases, mechanical systems can respond quicker to changes than electrical systems. So, for a long time, carb systems were much smoother on throttle response than FI systems. There's always a little delay on the electrical system to sense the changes and adjust. The manufacturers are finding ways to overcome that (better sensors, faster FI computers, different throttle configurations), so FI is starting to become "the norm".
Hope that helps...
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