2003 Kawasaki KX250 Piston Slap?

[NickThyPig]

Hi everyone! First post :p. I recently got an 03 KX250 from a local guy, and I took it out for a spin down the road. I was running it pretty hard, not max rpm's for a long amount of time, but just higher revs in general. It ended up stalling on me on my way back, it just kind of died on me. There wasn't a sound and the piston didn't seize (thought I overheated it), but it sounded almost clunky or clicky when I tried to kick it over. It ran for maybe 2 seconds and there was a higher pitched knocking sound then it stalled again. It did this once or twice more when I tried to start it so I just left it alone and walked it home. I took the cylinder head off and used my hand to pull the kickstarter, and I could hear the clunk still with the head off, and if I pushed down on the piston crown in the cylinder, it made the sound also. Maybe bad connecting rod bearing(s)? Made a video, but I can provide more info if needed. Link for video:

 

[Ol'89r]

Remove the cylinder and with the piston at TDC, grab the piston with both hands and try to move it up and down. If there is any up and down movement, you have a worn big end bearing and will have to split your cases. If the big end is tight, you need to measure your piston clearance.

 

[NickThyPig]

Remove the cylinder and with the piston at TDC, grab the piston with both hands and try to move it up and down. If there is any up and down movement, you have a worn big end bearing and will have to split your cases. If the big end is tight, you need to measure your piston clearance.

Thank you for replying! There is definite big end movement so I guess I'll have to split the case :/