You are correct that oil itself is not conductive, so it may seem puzzling how the leads of a motorcycle stator could short to ground when the engine is filled with oil. However, it's important to consider other factors that could contribute to the issue. Here are a few possible explanations:
Contaminated Oil: While pure oil is not conductive, if the oil becomes contaminated with substances that have conductive properties, it can create a conductive path for electricity. For example, if there is moisture, dirt, or metal particles suspended in the oil, it can create a conductive medium that allows electrical current to flow and cause a short circuit.
Faulty Insulation: The stator in a motorcycle generates electricity to power the electrical system. It is typically insulated to prevent the electrical current from shorting to ground. However, if the insulation on the stator leads becomes compromised or damaged, it can allow electricity to leak and create a short circuit. The presence of oil in the engine could exacerbate this issue by providing a path for the electrical current to travel.
Heat Expansion: When the engine is filled with oil, it undergoes thermal expansion as it heats up during operation. This expansion can potentially cause physical movement or deformation in the stator or its components. If there is already a weakened or compromised area in the stator leads' insulation, the expansion and movement caused by the oil's thermal effects could lead to a short circuit.
Manufacturing Defects: In some cases, manufacturing defects or assembly errors could contribute to the stator leads shorting to ground when the engine is filled with oil. For example, improper insulation installation or inadequate sealing of the stator assembly could lead to electrical leakage and shorts when exposed to oil.
To address this issue, it's important to have a qualified motorcycle technician inspect the stator and associated components. They can perform diagnostic tests, examine the insulation, and check for any signs of contamination or damage. If a short circuit is detected, they can provide the necessary repairs or replacements to resolve the issue and ensure the electrical system functions properly.