Carb problems
3 to 3&1/2 turns should be ok. start them slobbering rich and lean them out until they JUST START TO CLEAN OUT A BIT on the starting stand.....ok? they will still sound very much on the rich side. they will lean out when you launch 'em. the load on the prop is what leans them out. many new peeps try to make them sound like a gas car before launching..... this is way to lean. it will stall immediately. you'll probably have it to rich on the first couple of tries, but you'll get it after a bit.
make sure the props the right size and that your pipe is not set to short at first. this is important on initial setup.