PENGARUH UKURAN VENTURI KARBURATOR TERHADAP KINERJA MESIN HONDA ASTREA GRAND 145 CC

As the engine ages, generally the engine will lose its power and torque so that many of its users make modifications to the vehicle. The modification steps carried out include modifying the cylinder contents and valve size on the motorcycle engine. Previous studies have discussed the modification of the carburetor venturi on standard motorcycles, however, studies of modifications to the Astrea Grand 145 cc motorcycle have never been found. This study aims to obtain the influence and changes in the diameter of the carburetor venturi on the power, torque and fuel consumption produced by the Astrea Grand 145cc engine. This research was conducted by direct testing methods in the field using a dyno test tool to determine the power and torque values. Fuel during testing used the pertamax turbo 98. The test was carried out by comparing the power values, torque and fuel consumption using a 24 mm venturi carburetor with a 28 mm venturi carburetor. Variations in the size of the carburetor venturi will affect the results of the engine's work so that the value of power, torque and fuel consumption will vary. The results of engine performance testing, it can be concluded that the greatest power obtained using a 28 mm venturi carburetor the highest power is 19.3 Hp at an engine rotation of 10668 rpm. While the highest torque is 14.17 Nm at 8754 rpm. As a result of increased power and torque on the 28 mm venturi carburetor, then fuel consumption increased by 24.98% from the 24 mm venturi carburetor. The specific fuel consumption (SFC) results using a 24 mm venturi carburetor are 0.055 L/Hp.h and specific fuel consumption (SFC) and a 28 mm venturi carburetor are 0.074 L/Hp.h. Based on the data above, it proves the influence of the carburetor venturi size on the Astrea Grand 145 cc motor can improve engine performance, but fuel consumption has increased.