Hi jacked!.........
Man, this hi jacked thread went way over the top..............wow, lets get the guy some answers...........
Karl is right about the flame arrestors......they are to prevent backfiring of the engine, igniting fuel vapors that may have built up in the engine compartment.
The reason they have to be on, like you ask in the post about the dealer saying they could run lean, is because they are what creates the resistance in the throat of the carb, for the venturi effect to take place, sucking gas into the engine. Normally, when someone goes to an aftermarket part, like flame arrestor or exhaust, you need to rejet the carbs.........
To clean them. Look them over real well and make sure there is no fiber or paper type product in them (they are normally just stainless mesh) and if they are entirely metal, you can clean them by setting them into a bowl of gasonline (in a well ventilated area) and swashing them around or you can get some carb cleaner and spray through them really well. They don't normally, really need to be cleaned, unless they got saturated with oil.
The clamp..........I can't believe anyone didnt' come up with this. Am I the only McGyver in this forum..........get two clamps. Undo them until the ends come out from the threaded area. Now, take the end of one clamp, screw it into the end of the other clamp. Put the loose end on the other threaded clamp area and "wallah".......you have a large clamp with two different adjustments for tightning it down..............Good luck and if you need an answer, without being hijacked, send me a PM..............