As others have said, call the USFS office where you want to ride.
You'll get lots of conflicting opinions here on this forum, but you will get the actual true info from the Ranger District Office.
All national forests have a motor vehicle use map (MVUM).
Those maps show where various motor vehicles can ride and some roads may allow ATVs but not motorcycles (dirt bikes and mini bikes are considered motorcycles by the USFS - category MOT). Others may be the opposite. Some roads allow cars, but NOT motorcycles (we're talking not-street-legal motorcycles here).
USFS Definition - "MOT means all two-wheel motor vehicles like motorcycles, trail bikes, dirt bikes, etc"
So call the specific office, ask questions, get a map. Then you will know.