I typicaly only have to set mine a couple times a year... Winter and summer... I know it has something to do with the fuel... When they start running bad if I open a new can of fuel they snap right out of it... No adjustment necessary.. I suspect the Nitro is being vaporized by the high fuel temp.... Still have a couple more things to try though to be sure... Also as I said before this is only happening with my 4 strokes, not the 2...