It will be worth your while to get a maintenance manual for this bike. Clymer sells a manual for this bike for $22.72 + shipping. See the link below.
It will have troubleshooting and repair information for your problem.
This manual will have detailed step by step instructions to correctly do almost any maintenance tasks on your bike. This manual will pay for itself the first time you use it. It will be the best thing you will buy for your bike.
As for your specific problem. I don't know much about this particular engine. But my guess if that there is an internal check valve in the oiling system that is leaking and needs service. But with a service manual, you will have access to proper information instead of a best guess from a stranger over the Internet. You won't need to figure out if this best guess is accurate or just a bunch of B.S.
It will have troubleshooting and repair information for your problem.
This manual will have detailed step by step instructions to correctly do almost any maintenance tasks on your bike. This manual will pay for itself the first time you use it. It will be the best thing you will buy for your bike.
As for your specific problem. I don't know much about this particular engine. But my guess if that there is an internal check valve in the oiling system that is leaking and needs service. But with a service manual, you will have access to proper information instead of a best guess from a stranger over the Internet. You won't need to figure out if this best guess is accurate or just a bunch of B.S.