Now since you checked to make sure the metering rods were down you can see how easy they are to change. Take one out. The size are stamped on them. It's very small and I use a magnifying glass to read.

Also if you're going to check the floats you'll have the top off the carbs and can check the jets also. The primary jets are the 2 in front and secondary are the 2 ones in rear.

A stock primary jet on a 500 would be 386 which is a .086 jet. you just subtract 300 from the number.