The Honda TRX 350 from 1986 is experiencing a lack of spark, which can be a result of multiple issues such as a faulty ignition system or a worn-out spark plug. To diagnose and resolve this problem, it is essential to perform a thorough inspection of the ATV's ignition system, including the spark plug, ignition coil, and distributor cap. A professional mechanic with expertise in ATV repair can help identify the root cause of the issue and provide the necessary maintenance or replacement parts to get the Honda TRX 350 up and running again.