You're correct that some motorcycles, including certain Harley-Davidson models, do not have a traditional fuel gauge. Instead, they rely on alternative methods for riders to determine how much fuel is remaining. Here are a few common approaches:
Fuel petcock position: Many motorcycles, especially older models, have a fuel petcock or fuel valve located near the bottom of the gas tank. This valve typically has multiple positions, including "On," "Reserve," and "Off." Riders can estimate their fuel level by switching the petcock to the reserve position when the main fuel level is running low. This allows them to access the remaining fuel in the tank.
Trip meter: Most motorcycles have an odometer or trip meter that measures the distance traveled. Riders can reset the trip meter each time they fill up the tank and use it to estimate their remaining fuel based on their typical fuel consumption and the distance covered.
Reserve indicator: Some motorcycles have a reserve fuel indicator light. When the fuel level is low, this light will illuminate, indicating that the rider should switch the petcock to the reserve position.
Visual inspection: Riders can visually inspect the fuel tank to get a rough idea of how much fuel is left. This can be done by looking into the tank through the filler cap or by tilting the motorcycle slightly to gauge the fuel level based on its movement.
Experience and estimation: Experienced riders often develop a sense of how far they can travel on a full tank of fuel based on their riding habits, road conditions, and the specific motorcycle model they ride. This knowledge allows them to estimate the remaining fuel level based on their riding experience.
It's worth noting that some newer motorcycle models do come equipped with fuel gauges or even more advanced fuel monitoring systems. However, the methods mentioned above are still relied upon by many riders, particularly on older or more basic models.