I have a '99 Kawasaki with a 300cc single cyl engine. I couldn't get it started all winter even after a carb overhaul. I finally got it started when the temp got up to about 50. I took it in this spring and they replaced the nearly new spark plug with a new one. That got the starting temp down to about 40F. They said if it won't start now, it might need a valve job. The engine's never been apart in 17 years so that's a good possibility. I guess I'll have to pull the head off one of these days and have them ground.

“In a time of deceit telling the truth is a revolutionary act.”
― George Orwell

It's not over when you lose. It's over when you quit.