Check out the link I gave you, it describes the 3 needle set up perfectly and how to make sure your mid needle is set properly. I have a friend on that site that turned me onto it and it was a God sent to me when I messed with that needle for the first time. Also you have to remember that the "factory" needle settings are just a baseline setup and no 2 engines tune the same, so I would say set the HSN and LSN so it will fire up after you have checked the propper setting for the mid needle then tune from there. Real quick in case the link doesn't work, remove the HSN housing and look in the hole, with the mid needle flush to the carb body or very close to it your mid needle hole should line up with the HSN hole. Going that way with the mid needle, you should never really have to tune it again unless you get very good at tuning and notice the small change it will make for you in performance. Something else to consider is marking the carb body and needle so you can tell if it ever walks on you. Hope some of it helped.
