After falling victim to air entrapment in our XR650L oil pump after a crash, we investigated how to eliminate this issue. The OEM oil pump check valve is held shut by a spring that has considerable margin built into it from a seating force perspective. The pump is unable to overcome this seating force when air is introduced into the rotor. The air just recirculated internally over and over again with no indication to the rider that this has occured. We developed a lighter duty spring made from stainless steel that has 25% of the seating force of OEM. This allows the pump to purge an air pocket, while still fully seating and holding the pump check valve shut, reducing drain back to the cylinder head. 
 
If you're interested in learning more about the testing behind this, you can reference our blog post here.