There are a lot of possible problems.
How new are the sparkplugs and air cleaner ?
How long has the bike set with old gasoline ?
I would:
Install new spark plugs... they are cheap
Make sure the carbs are connected to the air box and that there are no holes in the air box
( the engines do not run well without the original intact airbox)
Check air cleaner and install if dirty .. they are expensive
Drain the carb float bowls and clean the petcock filter & replace any gasoline filters
Add Sea Foam to the gasoline at label amount.
Make sure your vent hoses are connected and not plugged up.
Then give us some feedback on how it is going.
Ride
Safely
