There's a limit to asking for mechanical guidance if you don't know enough to tell us that you've checked for fuel and spark on all four cylinders.
If you just installed new carbs, that sure suggests fuel / AFR issues. Did it run fine before? Why did you install 'new' carbs? It could also be spark-related - anything from coils, old wires, flooded cylinders / wet spark plugs. Check to make sure plugs are clean, dry, gapped correctly and ground each one out to check for spark. The basics.
If that sounds too involved, then there's no point asking for help - you'll need to bring it to mechanic.