Thanks for the input. I thought it would run wide open with out the screw as well, but I never was able to get it to fire once. Looks like I have some fiddling to do to get this going. I am running Wildcat Premium Extra fuel. It has 18% oil with an 80%synthetic, and 20%castor blend. I have had several people tell me that it will be fine as long as I keep it pretty rich.