gearcase oil leak

Mike,
This may have no connection at all but occasionally I had a drip of oil from an upper vent on my Honda fortys. I asked my mechanic if it was anything to worry about. He told me to let the engine sit for a few minutes after running before raising it for travel, that allows oil in the system to drain to the pan.
 
The Suzuki shop manual insists that new gaskets at each gear oil change are required. Their gaskets/o-rings are one time affairs, and I've proven that myself. You probably should just get Yamaha brand gaskets for the oil change plugs and change them out. They are super cheap and good insurance. I'm not real surprised that you are getting a leak from the top hole. The oil in the case gets pretty stirred up under normal use and if you are even slightly overfilled...not unusual...there will be enough there to wick out through any imperfections in the plug seals.
 
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