u/dpier1911

Hey everyone. I'm attempting to repair my 2016 XT250. Long story short I have about 30k miles on it, trails and highway but it stalled one day and didn't start again. I drained the oil to find bits of aluminum and steel, possibly the camshaft chain guide as well. I took the whole bike apart and found deep gouges where it looks like the chain was slapping around. The inside of the chain is also pretty chewed up but the sprocket looks OK. I have 2 questions:

1. What else do I need to inspect and replace (e.g. bearings, camshaft)?

2. How did this happen? Did I neglect some maintenance task that could have prevented it?

Thanks. This is my first time cracking a motor open this far.

Photos of damage attached, plus a bonus photo of the cylinder bore in case anyone has thoughts on that.

I came across these images while organizing some old photos. I lost the M16 somewhere in the desert while backpacking and the M21 was lost somewhere in BC or Alberta while I was working around the rocky mountains mist netting birds during grad school. Oh, and building lasers is one of my other hobbies.