[colt54]

hello all
im not sure what is going on with my kohler 301 but when its cold or chilly out it is makeing a loud pop when trying to start it and when it pops gas and air is coming out of the air breather some one told me it was a burnt exhaust valve but i have no clue this is my first cub and i never worked on a kohler before I have changed the oil and spark plug and put a new air filter on it and it still will pop when trying to start when cold when it does start a puff of smoke comes out but not much when runing it runs veary well and handles heavy loads well