Adjustment screws are on the front under the fuel bowl. Turning them in should lean the mixture, out should richen. I've been told to turn them in one at a time until it stutters then back it off. I can never remember whether it's back it out 1/4 turn or 1 & 1/4 turn tho. Hope this helps a little.
Another thought would be to check the choke. If it's set too rich you can loosen the 3 screws that hold the ring around the choke spring cover and turn clockwise to lean it up.