i have a 53 plate dna 125 and had same problem, worked fine for a while then stopped at the lights and started spluttering, ticked over ok and when u pull throttle it just chokes, has the bike been stood cold for a while, i had to get my carb cleaned out, simple enough to do have to take off the fairings though, cleaned mine out and fired it up, be wanred though if that is the problem your acceleration will be emense, mine now hits 60 in about 6 n half seconds,
liam vaissiere, June 2008