FUNNY THIS,, I WAS LOOKING FOR AN ANSWER TO THIS QUESTION AS MINE IS DOING THE SAME, I STRIPPED MINE DOWN AND THERE IS A PIPE THAT RUNS FROM THE FUEL CHAMBER TO THE ENGINE, THE PART THAT IS BOLTED ON THE ENGINE WAS CRACKED AND I AM GUESSING THIS IS SUCKING AIR IN ?,I HAVE REPAIRED WITH SOME EPOXY GLUE AND JUST GOING TO PUT IT BACK TOGETHER, BUT WAS LOOKING FOR AN ANSWER ON THE CHOKE MECHANISM ??. STRIP IT DOWN AND HAVE A LOOK SEE IF YOURS IS CRACKED ?
MARK, June 2009