Just bought a used 1999 KX 125. Cleaned the carb real good and changed the plug. The bike fired right up on the 2nd kick, ran for a few seconds, and then bogged out. I am told that this is what the bike was doing to the previous owner as well. Also, the plug seemed drenched w/ fuel after bogging out. I'm thinking it's running too rich, but I don't know how to adjust the air/fuel mixture. Please, if anybody could help it would be appreciated. Thanks.