Trike has no power after I messed with carb

I have been working on my first ATC/ATV - an 84 Yamaha YT125 three wheeler and after getting it going I noticed that the enginer RPMs seem to sort of run away with the choke open and cut out with the choke closed. I figured I would follow the instructions in the manual on adjusting the carb: set the air screw out 1.5 turns, set the throttle stop screw to your desired idle, set the air screw for max RPMs, then finally reset the throttle stop screw to desired idle. I dont have a tach or anything so I figured I would guess by ear (book recommends 1500 RPM).
Anyway it was kind of a disaster, I let the engine warm up and then gave it a try. Firstly the air screw barely came out 1.5 turns. It stopped just short of the full 1.5 revoloutions. Also the throttle screw didn't seem to affect the idle at all, except a certian point the engine would stop running. On top of this, the whole system seemed really dependent more on the choke setting than on anything I was doing to the carb!

Anyway I chalked it up to the cold weather and put the thing away until I could get more info on what I was doing. Any advice for this newbie? I can get the carb model # if it would help anyone walk me thru it...

Thanks in advance!!

[Cahdealme]

Your gonna have to play with it a little. Have any modifications been done to the bike that would effect airflow (exaust, filter, airbox,etc.). Has the bike sat up for an extended period of time. If not and the jets have not been changed than you shold be a good starting point. It sounds to me like the air fuel mix is to rich, try turning it in a little. Keep in mind, if there is any buildup of crap in the carb, it is not going to act right even if it is adjusted right. Also keep an eye on your spark plug, if it is running extemely rich it will foul a plug, in that case if you got it adjusted correctly it still wouldn't run right.

[TimSr]

Since you "just got it going" Ill make a guess that its not been going a little while. First thing I would do is remove the carb, and take it apart, remove the jets, and cleane everything. Pay special attention to the pilot jet. Make sure all orifices are completely open. Runaway idle speed is usually caused by a lean condition, but its usually a malfunction (clog) rather than an ajustment such as a jet size.