I don't want to state the obvious, but if your needle is to short when you open it wide open the velocity of the air rushing into the motor will bend the needle slightly toward's the intake and when you let off of the throttle the needle wont go into the hole, but will set down on the inside throat of the carb and you will be stuck wide open! This happened to me on a TRX 250R that i used to have, I saved it in the nick of time by pulling in the clutch and killing the motor. I put the needle in the clip position where there is more needle sticking down in the hole and was careful not to open it up to far on my way back home. Come to find out it wasn't even the right needle. I got a stock one and no more problem's. I know this doesn't answer any of your question's, but just consider it a free safety tip! lol
1985 Honda ATC 250 Big Red
"Ugly Betty" from the handlebars back it's a
1982 Honda ATC200es, from the handlebars
forward it's a 1988 Honda TRX 300 Fourtrax.
"If you wanna play, you gotta pay..."