I've since sold my ninja, but before I did, I wanted to solve the downshifting problem I mentioned in this post awhile back: http://www.ex-500.com/archive/index.php/t-45232.html
I listened to everyone's advice and tried to get the shift lever to be exactly 90 degrees so that the shift throw would be equal for upshifts and downshifts. This didn't help, and I still had the same problem. I tried changing oil too, to no avail. I started looking at the parts diagrams to find out if it could be something internal here: http://www.kawasakipartshouse.com/oe...ange-mechanism
The feeling of pushing the lever down was like you're turning anything through its detents, and you feel a slight resistance, then nothing once it passes over. The problem was intermittent. From this, and looking at the diagrams, I had a hunch that spring #92801 could be the problem since its responsibility is to keep the change lever pawl firmly pressed against the shift drum crown. Thanks to Urbane's help and his garage, we were able to pull the engine to get the gear change mechanism cover off and dive in. (Don't mind the stator off and flywheel gone, I was just replacing the start clutch springs)
After pulling the suspect spring off, I compared it to the new one.. You can see that one end of the old spring is stretched maybe 2mm past the new one on one side only.
I replaced that spring, put the bike back together, and now the problem is gone! Downshifts perfectly! I got really used to dealing with it, and never actually got around to fixing it until I sold it.
We tried to get to the spring without removing the engine, but we couldn't get one bolt out since the frame was in the way.. I'm sure it could be done with some clever combination of wrenches or universal joints. Either way, removing the engine from the bike is easy overall.
Hopefully this helps someone who may have the same problem. Ask me any questions if you have some. I have a few more pictures of the mechanism if people are interested.