666Devil666 Posted February 14, 2009 Share Posted February 14, 2009 hey guys and girls if any, was woundering how the fuel injection system works? YZF-R125 is my bike. Link to comment Share on other sites More sharing options...
pilninggas Posted February 15, 2009 Share Posted February 15, 2009 hey guys and girls if any, was woundering how the fuel injection system works? YZF-R125 is my bike. The previous method for getting fuel/air ~the mixture~ into the cylinder was to use a carburettor which uses the movement of air being sucked into the cylinder to draw fuel out of the carb float bowl, using the venturi effect. Fuel Injection uses pressurised fuel which is forced into the inlet (or directly in GDi type engines), in a very carefully metered way. EFI is controlled by an ECU (management computer), which looks at a range of variables to decide how long to inject fuel for (time of injection being reasonably approximate to quanity. Typically the variables sampled at millisecond intervals might be inlet vacuum relative to air pressure, inlet air temperature (cold air is more dense and therefore has a greater mass for a given volume), engine position in its cycle, engine speed, amount of throttle opening and exhaust gas composition. Ideally an engine will produce maximum power at full throttle if the engine is a little rich higher air to fuel ratio of less 14.7:1 ratio and more efficiency if it is leaner or stiochiometric air to fuel ratio of 14.7:1 or greater. Motorcycles have moved to EFI in order to meet stricter exhaust criteria. Carbs struggle to operate with similar precision over extended periods of time and with a tendency to wear rich would lead to the catalytic converters (a superflous device on a motorcycle?) being destroyed promptly. Lots of people will tell ypou carbs are better, the simple fact is on large motorcycles they are often intensly complex with a range of modes of operation ('circuits') which can all if out of spec lead to poor running. EFI has one or two injectors per cyclinder which follow a map-a computer algorithm in the ECU and this is much simpler, easier to fault find and much more tuneable. The fuel is pressurised by an electric pump. the injector then opens, squirting fuel into the inlet tract where it is atomised - forms small droplets - the mixture is sucked into the engine where the spark-plug ignited it, it does not explode. The hot gas expands and the piston is pushed downwards to turn chemical energy into mechanical work. The hot, spent gases are expelled by the piston on the exhaust stroke and exit to the exhaust system. hope that helps - this is my EFI experiment which i aborted due to house renovation: http://fzr1000injection.blogspot.com/2008/04/overview.html Link to comment Share on other sites More sharing options...
666Devil666 Posted February 16, 2009 Author Share Posted February 16, 2009 The previous method for getting fuel/air ~the mixture~ into the cylinder was to use a carburettor which uses the movement of air being sucked into the cylinder to draw fuel out of the carb float bowl, using the venturi effect. Fuel Injection uses pressurised fuel which is forced into the inlet (or directly in GDi type engines), in a very carefully metered way. EFI is controlled by an ECU (management computer), which looks at a range of variables to decide how long to inject fuel for (time of injection being reasonably approximate to quanity. Typically the variables sampled at millisecond intervals might be inlet vacuum relative to air pressure, inlet air temperature (cold air is more dense and therefore has a greater mass for a given volume), engine position in its cycle, engine speed, amount of throttle opening and exhaust gas composition. Ideally an engine will produce maximum power at full throttle if the engine is a little rich higher air to fuel ratio of less 14.7:1 ratio and more efficiency if it is leaner or stiochiometric air to fuel ratio of 14.7:1 or greater. Motorcycles have moved to EFI in order to meet stricter exhaust criteria. Carbs struggle to operate with similar precision over extended periods of time and with a tendency to wear rich would lead to the catalytic converters (a superflous device on a motorcycle?) being destroyed promptly. Lots of people will tell ypou carbs are better, the simple fact is on large motorcycles they are often intensly complex with a range of modes of operation ('circuits') which can all if out of spec lead to poor running. EFI has one or two injectors per cyclinder which follow a map-a computer algorithm in the ECU and this is much simpler, easier to fault find and much more tuneable. The fuel is pressurised by an electric pump. the injector then opens, squirting fuel into the inlet tract where it is atomised - forms small droplets - the mixture is sucked into the engine where the spark-plug ignited it, it does not explode. The hot gas expands and the piston is pushed downwards to turn chemical energy into mechanical work. The hot, spent gases are expelled by the piston on the exhaust stroke and exit to the exhaust system. hope that helps - this is my EFI experiment which i aborted due to house renovation: http://fzr1000injection.blogspot.com/2008/04/overview.html thank you!!!! Link to comment Share on other sites More sharing options...
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