You mention that it "seems" to be getting spark. Did you remove and ground the sparkplug and crank the bike over to see if the spark was there?
If you are sure that it's getting gas, so I assume that it must be getting air, so the only problem is the spark. Just for the hell of it try to use some starting fluid to see if it starts to sputter. If it does, it could be the carbs. Did you clean the little filter screen that is inside the carbs themselves? It's real easy to overlook it. SV's have a little screen in the carbs that needs to be cleaned regularly since it gets clogged with debris. It's right behind the float bowl valve seat.