My bike keeps fouling out the plug. I have cleaned the plugs, air filter and carburetor. When the problem happened I was out riding and it just starting bogging (my thought was a foul plug). I changed the plug and it would foul again in a minute or so then not run the engine. This is when I cleaned the air filter. After that it would still bog down, but not foul out completely where the engine couldn't run. Cleaned the carb here still the same. It seems to bog around mid throttle.