I recently got the gearbox back into my Cali Stone after replacing some seals and re-shimming the shift drum (thanks to Canuck 750 for the use of his clutch assembly tool). I'm pretty happy with the results - no leaks, and shifting is considerably smoother - but I've noticed something weird started happening at stop signs and red lights. I would downshift to 1st as I came to a stop, but when it was time to go, I'd find the bike was in neutral. It never slipped into neutral while I was driving, just at a stop. When I tap down from N to 1 it engages solidly and won't slip out on its own.
Eventually I figured out that my old habit of tapping down on the shifter a couple of times to make sure I'm in 1st was (ironically) nudging the shift drum to a position where it could slip out of gear on its own. As long as I don't touch the shifter after I get it in first, it will stay there until I select neutral or upshift to 2nd on the takeoff. Now I'm trying to break what was probably a bad habit anyway, and leave the shifter alone after I get it into 1st. I'm wondering though if anyone else has seen this and if there is a fix for it. I've thought about adjusting the shift linkage, but it seems to be pretty centered in its resting position - there doesn't seem to be tension on it backward or forward. I can learn to live with the gearbox as it is, but if it can be tuned up a little more that would be better. Thanks for any ideas that you care to share.