KDX 220 stuck in gear

[GabeM]

Went riding with my son and his 99 KDX 220 yesterday. It was very muddy in some spots and he was running pretty fast.
As he tells me, he was downshifting when the bike locked up on him.
I couldn't get the bike out of gear. It was stuck in 4th. If I shifted down (into 3rd) the tranny would lock up even with the clutch pulled in the wheel wouldn't turn, but I could shift it back up to 4th and the bike would start. I got it back to the truck this way. I checked the shifter lever to see if a rock or something was keeping it from downshifting, but nothing was in it's way, I even removed the lever all together and moved it up one tooth, but that didn't help.
We got home and washed the bikes, I usually start them and run em up and down the street after a good wash, so Luke jumps on his and the same thing as before, it would start in 4th gear, but was stuck there. After he goes down the street a couple of times, the bike jumped out of gear into neutral, and then worked fine after that.
I ran it up and down the gears myself and everything seemed normal. I changed the trans oil and didn't see anything wrong, oil was fairly clean as it should be and couldn't find any metal particles.
Anyone here ever have that happen to them? I just put the bike up for sale last week and want to make sure it's OK or I'll need to have it worked on.
Any help would be appreciated
Gabe

 

[dirt bike dave]

Could be the shift shaft return spring popped off and then somehow slipped back into place.

Had one pop off on my old '84 KDX, and it stuck in gear. I had to remvoe the right side cover to put it back into place. The return spring is on the end of the shift shaft that is on the opposite side of the motor from the shifter. You can view diagrams of your motor at www.buykawasaki.com

 

[mideastrider]

My kdx stuck in gear on one of the first few rides I took it. Was way back in the woods I rode about an hour in 3rd gear when it just started working again. Worked fine the rest of the day. Was afraid to take it out again without checking. I pulled the clutch cover off and found the governor lever for the power valve had broken off and was down in the area of the shifting drum. It had it jammed up for awhile and moved a little and it started back working.

 

[GabeM]

when it was stuck, did it do what mine did by locking up when I tried shifting down one gear?