With all that work you are doing on your tractors over the last week, I think you should be using this to reduce your fuel going off and gumming up the carbs and weakening the fuel lines. I know you have used Aspen 2 on your hedge cutters, Stihl do their version for 2 and 4 strokes. I have got this in my 1050 and will gradually use this product on my other tractors. I have been using this on my modern Honda mower and it fires first time. Just a thought.