NK, I was referring to blue spark, white spark or yellow spark and what that indicates. The colour of the spark plug itself is helpful. Straight fueling is becoming more common so this info gives a quick indication whether to pull the exhaust off and examine further. Yesterday I pulled out a mower after a long time and there was thick fuel the bottom so I added a tiny bit of petrol before adding a fair quantity of 2 stroke mix. I'm not being foolhardy am I, as it could cause it to become 30:1.

Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!