Have a look at the carb and see if it has a choke butterfly. If it does check to see if it closes when you operate the pull start. If it doesn't there is an issue in that operating mechanism.
Also if it does have this butterfly, there will be a mixture screw on the side of the carb. It may be set too rich. I'll refer to my manual for setting procedure. In the meantime, check the carb and maybe post a picture and I'll see if I can help there.
Cheers!
