These V4s don't like to go out without a hat on, so in other words, air box and filter need to be in place.
Next I would check to make sure all the carbs are properly seated in their boots. Sometimes,,, like most of the time,,, a fellar needs to seat these things back and forth a few times to get them to stay.
If that don't help, fire it up and then go around the intake area with an open unlit propane torch and see if you notice any difference in the RPMs, if you do you can now dig for an intake leak.
Then come back here and ask some more.