What is the spark plug gap on a 1980 suzuki gn400x?

Hello just picked one of these bikes up for my girlfriend to start out with its a pretty cool bike. The gap is .6 to .7 using a gnk plug metric bike. This one was burning rich and had a hard time with smooth idle any ideas? Hello great starter bike the gap is .6 to .7 gnk plugs work the best and the heat of the plug might have to be changed to make the bike run better.