You need a 20w-50 or something close to it. Also you DON'T want to use an energy conserving oil, like you use in your car. It will make your clutch slip as it has agents to make it too slick for wet clutches. I use a Diesel oil as it doesn't have the slick agents in it.
You can usually find a 15w-40 Shell Rotella at Walmart and it works just fine for my bike.
A Yamaha Maxim 650 motorcycle has a 4-cylinder engine. The Yamaha Maxim 650 will hold 3.1 quarts or 2.65 milliliters of oil with the oil filter attached.
Yamalube motor oil
Yamalube motor oil
Look under the bike for the drain plug under the motor area.
Hypoid 80/90W. Check www.xjbikes.com
Yamalube motor oil.
yamalube or 10w40
yamalube 4
20/50
yamalube is the best
SAE 20W40 type SE motor oil for > 40deg F SAE 10W30 type SE motor oil for < 60deg F
20w-40