My Flying Horse, 66cc, will start up, but only for a few seconds before it bogs down and stalls when I pull the clutch in. I had the same problem yesterday but was able to get it started and go for a 30 mile ride. The engine has at least 500 miles on it or better and I'm using 40:1 ratio. I noticed the spark plug was wet but clean. I've cleaned the exhaust for the 3rd time too. No leaks are appearing in to the magneto and magdet. I'm not sure what to check out now.