Re: in need of info
Yes, you must do a complete tear down to replace case half mating gaskets on all engines that use them.
Unless your engine is running really badly, from a leak at the case halves, I would guess you probably have a leaky petcock and/or a leaky float valve sending fuel on down when the motor is no longer running.
Clean the engine well and dry it. Place clean, dry cardboard beneath the engine. Inspect after a few hours.
On better quality motorcycles, mechanics dust talcum powder on the engine, after cleaning and drying, to locate very, very small seeps.
My goal is cheap, reliable, personal transport, below the tax collector radar. Fun counts for a lot!