Bought this bike literally 2 weeks ago...engine seized up and I got around to taking it apart tonight and this is what I found...what's next?! please advise as I'm new to motorcycles and don't want to spend a fortune. I paid $750 for this one from a motorcycle mechanic!! I guess I am just too trusting of people...

to clarify, i was just riding around town going maybe 25-30 mph and there was plenty of oil when i opened it up.

Welcome to the site as a new USER. Enjoy and ride safely. Doesn't look good! I'd say your valve guide(s) seized causing a valve stem to break off and drop down into the combustion chamber. That punched a hole in your piston. Step 1 is to check for replacement parts. Piston, valves and head to start with.

The other possibility is your timing chain broke or slipped. That would cause a collision between piston and valves, likely breaking one off and causing the damage in your photos.

Someone here will add to this. Hopefully with information more helpful.

Post on over in Bike Problems. Good luck!

many thanks! I didn't realize I had posted under the wrong category - will an admin pls move my post?

You're OK for this as an Intro. It just will develop better in Bike Problems. Start a new topic, cut and paste. Good luck.

That one dun blowd up.

I would agree that it looks like a valve seized and smashed a hole in the piston. It's gonna be a full rebuild. Since it hit hard enough to smash the piston, I'd want to address the bottom end as well. The connecting rod could be bent, which means the crank bearings took a serious whack as well. I've no idea on parts or spare engine availability.

Welcome! Curious how many miles are on your 39 year old machine?

Welcome to the site! Sometimes things like an engine blowing up just happen. If the bike overall is worth doing a rebuild on, finding parts won't be a problem. A good thing that'll come of this, if that's the course you pursue, is that once it's done you'll have good reason to be confidant in your XT250 with a fresh engine rebuild. Keep us posted as you sort this out, and best of luck whatever you choose to do..

Welcome

thanks for everyone's input - keep them coming as i welcome any insights. I've order a cylinder and matching piston (2mm overbored, from a running 1981 xt250), a set of valves, and a gasket set from ebay. At my disposal (all came with the bike purchase) is another cylinder head, lower crankcase, cam shaft, flywheel and transmission etc. - basically a second engine minus the piston and clutch assembly. So i think i can use this as a learning process and get the bike rebuilt. Cheers!

not sure the odometer is trust worthy but it says around 8000.