I made an interesting discovery today.
When it ages, modern crappy gas behaves in small Kohler engines, like a super lean running engine.
The Cub: Ratty old 122 that usually runs well.
The symptoms: Starts kinda grudgingly then runs ok, until after a while you can hear the exhaust note change a bit...the power begins to drop off, then it finally stalls (after feathering the choke to keep it alive a bit longer) andddd....it stalls (often with a backfire).
Cool down, and it'll run again until the SAME set of symptoms appears.
I did all the normal stuff. Checked fuel flow ( no grass is going to grow THERE for a while) , spark plug, spark function... all OK. Clean fuel tanks, filter, sediment bowl. All ok.
As I was messing with the tank, I noticed the fuel didn't seem as aromatic as normal gas should be. There was not nearly the same strong fumes. Hmmm... this gas is only a few months old, still....
Dumped the gas, and went and got some 100% gasoline gas. Came home, filled the tank of the 122 and all was well. Engine fires almost as soon as the key is turned (which is good as the compression release doesn't work on this dog!) . Ran it for hours, with zero problems. Restarts hot, never stalls, idles well. Beautiful !
So...I know there's been other threads about these symptoms and I KNOW that modern gas is crap, but it took until today to realize "this thing should run fine! It's all the way it should be. The Kohler engine is a simple, reliable mule. What's wrong???"
The only thing left was the gas.
