86 zl600

Picked up a 1986 ZL600. It does not have the airbox on it. I know It doesnt have to have it to run so I was wondering if anyone knows how to do it and can tell me the details on how. Trying to get this thing going. Any help would be appreciated.

This is my first post and I've had my zl for a month and I've rode it 3 days. After I ride for 2-3 hours if I park it I can't get it to start. I try ether and what not and nothing seems to work. But if I change the plugs it will fire right up. How do I fix this?