We have a tilly on our gx390 and this weekend was the first race of the year for it .It was running out of fuel on the top end making it sound just like a rev limiter max recall was 5500 , it did this before but i could always adjust the h side too clear it up but it doesnt make a difference now , I was talking too a couple people that said about using some kind of guage and poping the valve but i dont have no ideas about these tillys.