Ditto!! I was going to post this same thing tonight but looks like I was beat to it. All other gears are great and 3rd gear is ok except when accelerating it's worse than when cruising along. It seems the more load that's on it the more it happens, feels violent at times.
It really pisses me off because my cases were just put back together and the entire motor rebuilt less then 2 weeks ago and I don't remember this happening when the kickstarter gears went out. I'm guessing something got messed up when that happened last summer and I since I didn't ride it after that I never knew about it until it was already together. Sucks...everything was running, idling, new clutch, bearings, seals, piston, rings, valve seals, all gaskets....back apart it goes.
Trikes
1984 Honda 200x, 1984 Honda 200m
Bikes
1995 Honda CR125R, 1985 Honda XL100 (gone), 1982 Kawisaki KZ550 LTD,
2001 Yamaha TT-R 125L, 1983 Honda XL185S (current project), 2001 Suzuki SV650S