Altitude, temperature, humidity, air density all have their affect on jetting. Someone like Rich Rohrich, who have their bike jetted spot on, would have to change their jetting often, sometimes a few times a day just because of different weather changes. As for a 122 main, what you were experiencing was probably detonation from a too lean main. There's a reason they have small increment jets. going from 150 to 122 in one step is very dangerous(it could very easily seize the engine), not to mention dumb(no offense as you might not of known better.) But you did say that aside from detonating, your bike was running better no? You'd have to find the right jet, somewhere inbetween 122 and 150. But allways start from a rich main and go leaner in small increments.