Motorcycle engine performance is highly dependent on the air intake system, which plays a crucial role in the combustion process. One common method for improving engine performance is modifying the intake system, either by installing additional devices or adjusting the quantity of incoming air. One innovation that is starting to be widely used is the Jet Ranger, an additional device on the intake duct that is claimed to be able to increase air flow into the combustion chamber. This study aims to determine the effect of the use of Jet Ranger and variations in the quantity of incoming air on the maximum power of a 150 cc motorcycle engine, as well as to analyze the interaction between the two variables. The study was conducted using an experimental method with a two-way factorial approach. The independent variables in this study consisted of two factors, namely the use of Jet Ranger (without Jet Ranger and with Jet Ranger) and variations in the quantity of incoming air divided into four levels (0.008; 0.012; 0.016; and 0.020 kg/s). Maximum power testing was conducted using a Leads dynotest, while the mass of incoming air was calculated based on air velocity measured using a digital anemometer. The test data were statistically analyzed using a two-way ANOVA to identify the effect of each factor and the interaction between them on engine power. The results of the study indicate that the use of Jet Ranger significantly increases engine power. Variations in the quantity of intake air also significantly affect the power generated. In addition, the interaction between the use of Jet Ranger and the quantity of intake air is proven to have a significant impact on increasing the maximum engine power. These results are in line with the theory of intake systems which states that increasing optimal air flow can increase the volumetric efficiency of the engine, and are supported by findings from previous studies. Therefore, these findings can be used as a reference in the development of air intake systems on motorcycles to achieve more optimal engine performance.

Disc discs are the main component in a motorcycle braking system that functions to convert kinetic energy into heat energy through friction. The geometric design of the disc, including the diameter and number of holes, affects the effectiveness of braking as well as the heat dissipation ability. This study aims to analyze the effect of variations in diameter and number of holes on disc discs on braking distance and disc temperature. The research method used was an experimental method with three variations in disc diameter (190 mm, 220 mm, and 260 mm) and three variations in the number of holes (30, 36, and 42 holes). The test was carried out through a controlled braking procedure at an initial speed of 40 km/h on flat road surfaces with stable weather conditions. Braking distance data is measured using ultrasonic sensors, while disc temperature is recorded with a high-accuracy infrared thermometer. The results showed that the diameter of the disc disc had the most significant influence on the braking distance. The larger the diameter, the greater the braking moment resulting so that the stopping distance becomes shorter. The number of holes in the disc also plays a role in heat dissipation because the holes enlarge the heat dissipation area. However, the increase in the number of holes tends to slightly increase the braking distance due to a reduction in the area of frictional contact field. The most optimal configuration is found on a 260 mm diameter disc with 42 holes, which results in the shortest braking distance of 8.25 meters and the lowest temperature rise of 4.47°C.  Statistical analysis using Two-Way ANOVA confirmed that the diameter and number of holes had a significant effect individually, but there was no significant interaction between the two. These findings confirm that the selection of the right disc dimensions is critical to improving braking performance, thermal efficiency, and rider safety.

The amount of load on the vehicle requires a balance current and voltage. To fullfill the requirement, vehicle use a energy stroage media called lead acid battery. Although the lead acid battery have a impaccable durability, the performance will be decrase as long as use, especially in term of power and durability. The downgrade performance from the battery make high cost replacement, meanwhile there is a change to fix the battery. One of the methode to fix is replace the cell and added H?SO? electrolyte concentrat variation. This research intend to examine repairment effectivity and electrolyte concentrat variation on power for used lead acid battery NS40 type. H?SO? electrolyte that used is 30%,40% and 45%  examine with 5 static dummy load 1 ? 100 W pararrel circuit. Each electrolyte examine 60 times to obtain performance and durability data. The results show that increasing the concentration of H?SO? has a significant effect to produce the voltage and current. At 30% concentrate, an average voltage is 9.8 V and the current is 30.125 A at 40% concentarte, the voltage is 10.18 V and the current is 32.731 A and at 45% concentrate, the voltage is 10.19 V and the current 33.375 A.