I use this on my cb350 and works excellent: Engine Timing Light with Spark Plug Tester,Inductive Timing Light Gun Timing Light Ignition Testers Engine Ignition Coil Tester for Car Motor Motorbike Vehicle Motorcycle Marine Lawnmower https://www.amazon.com/dp/B07NRNPR6H/ref=cm_sw_r_cp_api_glt_fabc_WDK4K7HRY5KHSEPKHH05?_encoding=UTF8&psc=1

Any 12v auto probe will work but I use this one. I cut the clamp off though so I could ground it easier: Heavy Duty Automotive Circuit Tester, Premium 6-24V Test Light with Extended Spring Test Leads & Sharp Piercing Probe, Circuit Voltage Tester with Replacement Indicator Light for Car/Vehicles https://www.amazon.com/dp/B07Q3622FT/ref=cm_sw_r_cp_api_glt_fabc_Y1TKSZZ9J0S3XBCG3HMT?_encoding=UTF8&psc=1