So i've toyed with the 84 puch cobra last night... I removed the air box and now it idles and runs top speed with no problem. SO... i opened the air box to check and clean the airfilter, and no filter was in there. So what do i do? With the air box on it wont idle and then 4 strokes at the top end. Rebuild the carb with a smaller jet, or get a K&N filter and have a great fast ride.