Yes, oil on spark plugs can cause a motorcycle not to start or run poorly. When oil seeps into the combustion chamber and coats the spark plugs, it can interfere with the spark plug's ability to generate a spark, which is essential for igniting the air-fuel mixture.
If the spark plugs are coated with oil, it can prevent them from producing a strong spark or cause a misfire. As a result, the engine may struggle to start, run rough, or fail to start altogether. You might experience symptoms such as difficulty in starting the motorcycle, poor acceleration, rough idling, or engine misfires.
There are several possible reasons for oil on the spark plugs, including worn piston rings, damaged valve seals, or a leaking head gasket. If you suspect oil is getting onto the spark plugs, it's important to address the underlying issue and fix any oil leaks or engine problems causing the oil contamination. Consulting a mechanic or a qualified technician is recommended to diagnose and resolve the issue effectively.