I run mine at 240 to 250. I would get a bit nervous if it hit 300. Just my opinion. They really don't wake up until you get a gallon through it. Break in went smooth but until I hit the gallon mark, I was wondering if I had wasted my money because it didn't seem to make much power and wouldn't hold a tune. Now that its got about a gallon and a half through it, I am really impressed with RB's quality and power. It fires up easy, idles perfect and I rarely have to even touch the needles now.