Set the nipple to the rear bolt,,,,if carb is on back point it to the front bolt as it is on my 4500 and set the low with a blowing of air till you can just hear it comming out. Set the high to 2 1/2 turns out and you will be real close....trust me....works...i have no problems with any of my tigres...and also use tigre fuel from byrons....the best...12 perc. oil...