Hi Jerry -
While using oxygen sensors is probably a good idea, I would suspect your system wasn’t tuned to that condition originally.
I’m not sure what kind of carburetor or fuel injection you’re running, but that looks a lot worse than just a bad tune.
You may want to check on the basics….
- Float levels too high?
- Fuel pouring in at Idle?
- Idle Screws set way too rich?
- Leaking Power Valve?
Are the plugs the same on both sides of the engine, and are they the same front to back?
Anyway, with your plugs like that, your O2 sensor is going to tell you that you’re running way to rich. You might be able to get a jump on the tuning by checking on some of the basics…
Do you know a buddy with the carburetor you could borrow?
Of course you would want to start with a set of fresh plugs.
I’m sure that there are a lot smarter tuners here than I am. Hopefully some of those will also give you tips.
Let us know what kind of carburetor or fuel injection system you are running.
Rocky