bike keeps racing idles poorly

i thought it was my throttle at first so i lubed it up but it keeps doing it. when idling the rpms will jump up to 4 or 5 grand and sit there and as i mess with the choke, if i dont get it just right it dies. So at stop signs i have to keep revving up slightly. The carbs were rebuilt last year. The mechanic who did it told him the only way it will run good is with half choke all the time. Im not sure why. I was just out riding it now and it died coming up to a stop light, it restarted but the throttle felt really soft. Not sure what it is. any suggestions? My father owned the bike before me and was the one who had the carbs rebuilt. The bike is a 85 700xj

 

first, the guy that rebuilt the carbs should probably refund your dad the money. any mechanic that tells you that you have to run it with the choke because that is the only way it will run is probably a prime candidate for another line of work.

first: get an unlit propane torch, with the bike idling, move it around the throttle shaft seals, the boots, etc. if it changes the idle, you have air leaks. if the shaft seals are bad, see number 2.
second: turn the idle screw between 2 and 3 down so that it will hold about 1050rpm. if it wont idle at all, reset the idle mixture screws. they are the little bronze screws by the choke hats. turn them all in until they bottom out (not tight) and turn them back out 2.5 turns. this will set your idle baseline. if it still wont idle, you will need to tear the carbs down. it's not that bad. just time to do it right is all.
if you look up posts by RickCoMatic, he has an awesome guide on the carbs.

hope this helps, and the guys here are always glad to help

 

ok thanks. Ill give it a shot

 

just look at any post by Rick and you will see the links in his signature

 

i took off my carbs today and cleaned them all out. The bike is running much better now. The throttle seems to stick here and there but im happy to be riding again. Thanks for the help

 

get some graphite for the throttle cable, get that thing lubed up. rule that out as the cause.
is it really hanging and then drops quickly or is it slow to return?
slow to return might be an air leak.
spray some carb cleaner around the carb boots and throttle seals to see if that will change the idle

glad to hear it is running better for you