There could be several possible reasons why your Pulsar 150's low beam light is not working while the high beam is functioning correctly. Here are some potential causes to consider:
Faulty Bulb: The low beam bulb might be burnt out or damaged. Even though the high beam works fine, the low beam filament could be broken. In this case, replacing the bulb should resolve the issue.
Wiring Issue: There could be a problem with the wiring or connections specific to the low beam circuit. Inspect the wiring harness, connectors, and switches related to the low beam light for any loose or damaged connections. Repair or replace any faulty wiring components as necessary.
Fuse Issue: Check the fuse related to the low beam circuit. A blown fuse can cause the low beam light to stop working while allowing the high beam to function normally. If the fuse is blown, replace it with the correct rating as specified in the owner's manual.
Faulty Switch: The switch responsible for controlling the low beam might be defective. Try toggling the switch a few times to ensure it is engaging properly. If the switch is not functioning correctly, it may need to be replaced.
Voltage Regulator or Rectifier Issue: A malfunctioning voltage regulator or rectifier can affect the electrical system's performance, including the low beam light. This is less likely, but if you suspect an issue with the charging system, it's worth having it checked by a qualified technician.
Regarding the lean fuel mixture and low RPM setting, it is unlikely to directly cause the low beam light issue. However, if there are underlying electrical issues or if the bike is not running optimally, it's recommended to address those concerns as well.
If you are unsure about diagnosing or resolving the issue yourself, it's best to consult a qualified mechanic or an authorized service center for a proper diagnosis and repair. They will have the expertise and tools to accurately identify and rectify the problem with your Pulsar 150.