Idle Question

Just had a question, i have a 82 GL500 that has been bobbed out. i have straight pipes with 12" shorty mufflers and also Air pod filters rather than the air box. i rejetted this bike when i was building it and i put in 90/120 jets in it. my problem is that when it gets warmed up it wont idle below around 1800 RPM. and this is with the idle ajustment screw all the way out. i have checked for vac/air leaks by spraying brake clean and also had a smoke test done by a local mechanic and there are no vac/air leaks in the bike. i was wondering if the jets may to big to cause it to idle to high or would that even matter? if i should put smaller jets in it what are some step down combinations of jets that i can use rather than the 90/120. thank you very much for the help. -Nathan