Small Engines (Lawn Mowers, etc.): Kohler 8HP running lean, test gas, cub cadet

Question
I checked timing and adjusted to specs.Ran high test gas, new point& plug ...But engine runs hot,to the point that muffler glows red (evening when its getting dark)& engine back fires ,from running lean .I ajusted screws & cleaned carb & still it runs lean . Question ..eng.serial # 2018467 is there a richer needle ? My local shop is no help. I'm thinking if not jet maybe govenor needs to be adjusted... Do you know how that is performed ?
Engine is in Cub cadet 126 . Thanks in advance

Answer
RICK, HAVE YOU CHECKED THE VALVES.?  IT MAY BE THE CULPRIT.
RUN A COMPRESSION CHECK AND SEE.  TRY RUNNING WITH THE CHOKE PARTIALLY CLOSED TO SEE IF THE REDNESS DISAPPEARS IF IT DOES THEN YOU KNOW FOR SURE IT IS IN THE CARB.  I WISH I COULD BE OF MORE HELP WITH THIS BUT I AM WEAK ON KOHLER MOTORS.

GEORGE