i have a Gilera dna 50 with a malossi 70 big bore kit, the bike runs fine with standard air filter box (filter element removed) but since putting a K&N type filter the bike revs superb in the workshop but when under load just dies. i have fitted larger main jet and leo vinci exhaust.
Any suggestions much appreciated.

Dave Richards, February 2010

does it run ok if you put the old filter back on?it sounds like carburation so its either getting more air with the new filter or less, ok do this take the air filter off totally and see if its better or worse ,if its worse then your kn filter is letting the air in faster and the main jet needs to be bigger if its better then you need a smaller main jet,i would say its more likeley to be running weaker with akn style filter as the air flow is fast so it will need jetting up i expect.

adam bike doctor, February 2010