[Synchro909]

If the engine is tuned anywhere near correctly, the need to remove carbon would be rare but I've done it using the water mist method.
Use a spray bottle of water to blow a mist of water into the intake of the carb until the motor nearly stops. Give it just enough time to recover, then repeat but more water till the motor quits. Leave it overnight (don't forget to turn off the ignition) and when you start it in the morning, the water has penetrated the carbon and the heat causes it to "explode" out of the carbon, dislodging it. The carbon goes out the exhaust.