The dna's have a fuel pump and a vaccum tap and also a non return valve,the pump is at the bottom of the tank (right under the bike) which is operated via a vaccum hose from the inlet manifold this basically pumps the fuel uphill to the carb so if there is any leaks in the vaccum hose it simply wont go uphill against gravity,the non return valave is situated on the right hand side next to the frame rail and is inline the fuel hose from the pump to the carb this is there to stop the fuel from returning in the hose to the tank after the engine is stopped these valves do sometimes go faulty and need replacing,the fuel vaccum tap is also on the bottom of the tank and will not allow fuel to flow unless a vaccum is being pulled from the same pipe that the pump uses when the engine is running so again if this vaccum pipe is split or fallen off it will not work.i would suggest taking the fuel hose off the carb and trying to start the bike with a good battery,the momentum of the engines cycle should provide enough vaccum when turning over to pump the fuel out of the end of the hose if it doesnt after about 30 seconds of cranking then there is a problem ,if it does comeout put the hose back on the carb and continue cranking until it starts up.any questions just aks for me and ill help u out :D
adam bike doctor(of milton keynes motorcycle centre), July 2011
