my bike does exactly the same when I start it. imedialtely after it starts if i turn the throtle anyway else than very, very slow while pushing the choke in, it dies. After it goes over 3k-3.5k rpm everything is OK. It does not do this if it is connected to another battery, so i suspect it is an electrical problem. Maybe the battery is too small to provide the power needed for the ignition after it is drained by the electrical starter...