I just recently got an 06 KX65 and took it for the first ride after cleaning the carb and tank. Starts and runs real well with some fresh gas, just needs some fine tuning of the carb and other minor things. Overall pretty good but the trans feels a little weird. This is my 2nd 65 and the other one didn't do this. So when riding and shifting, sometimes it will hit a neutral between gears and it popped out of gear a few times. All the gears and neutral are there and where they're supposed to be, it just feels like there's multiple neutrals for some reason. I also had the same thing happen when shifting through the gears with the bike on the stand (not running). I am also full grown (34yo, 150lbs)

 

I've just sorted mine today, the side casing must be worn so the little nib bit that pushes against the gear shifter shaft isn't doing it's job. I've put a spring I've the shaft bit so touches the side casing nib bit and it works perfectly. I'll try attach pics.

Thats the nib bit that must be worn


I took the spring off my road motorcycle axle stand lol and cut it in half ,fits perfect