After tearing apart and reassembling the clutch, installing a new clutch cable, I've finally got this bike turning over and running, but it keeps dying on me mostly when it idles too long or when change from riding downhill to a slight incline. I'm not entirely sure why it's dying but I figured I'd start by cleaning out the carb. The previous owner ran this thing with no air filter on the carb, i'm not sure why. I'm suspecting the air / fuel ratio is off so I'm looking for an air filter to put on the Bing carb. It's got the round float bowl. Can anyone point me in the right direction as far as what air filter to buy?