There is short and short when it comes to LSN's

Like Matt said, it's all to do with if the needle comes out of the spray bar or not.

For the purpose of our discussions on here, if the needle stays in the spray bar at full throttle - it is classed as a long needle.
It requires the HSN to be set quite rich to allow enough fuel past the tip of the needle at or around WOT. If the HSN is not rich enough you will get lean bog (also when the tank level gets down).
The idea behind the long needle is a nice smooth power curve and good economy. It does require a different tuning teqhnique from the normal "shorter" needle. Nearly all your tuning is done with the LSN.
Generally HSN around flush and LSN around 2 turns in from flush will get you running, and fine tune with the LSN from there.

Again, for the purpose of our discussions on here, any needle that retracts completely out of the spray bar at or around WOT (even if it's only by a small amount) - we can class as a short needle.
Because the needle comes completely out of the spray bar at WOT you can run the HSN a lot leaner because there is no restriction to the fuel flow at higher revs.
This means you can tune with both the HSN and the LSN like most other carbs out there. The point between getting it right and getting lean bog is far wider, so tuning for people learning, or people that have trouble understanding the concepts of tuning is generally easier and more trouble free with the shorter needle.
Generally HSN around 1 - 1.5 in from flush and LSN 2 - 2.5 in from flush will get you running and fine tune from there.

Regardless of what needle you are running it is very important to set the idle gap at .7 - 1mm before you start.
The most common fault is for people to have too wide an idle gap, then tune with this fault. You end up with a motor that is way too rich on the bottom end and too lean on the top. The rich bottom end and large idle gap give a false idle, which appears to be correct unless you know what to look for.
You end up with a motor that appears to run OK, but will normally get hotter as the tank level drops, and will start lean bogging toward the end of the tank. Another tell tale sign is the revs holding up over jumps even though you have released the throttle.
This problem can be solved by setting the idle gap correctly and then setting the LSn correctly using the pinch test etc. This has all been covered in previous posts - plus I have ranted on long enough