What I have is a 1984 XL250R with an unknown year XR rear-end and maybe the same, single carb engine. Number on engine is ME06E-5204756. Very hacked-up airbox mod that I was thinking about changing. But that was then... Last saturday I was in a hurry to get into town & forgot to check the oil. 5 miles down the road, started losing power so I figure the gas needs to be switched to reserve, nope! Piston seized, two or three breaking sounding noises - maybe clutch rattle? - rear tire locked-up and I went sliding for a couple seconds while in 5th gear doing 50 before pulling the clutch in. Today, kickstart just stops solid. I tried rocking the bike backwards in 6th gear, still shifts ok, but no movement out of the crankshaft so I think the connecting rod is still in one piece. But the scary sounding noises and the thought of doing a major overhaul is making me think I'd rather just get a whole 'nother engine! So what I'm wondering is, what options do I have? Like if I search ebay, there's a bunch of different engines, but what'll bolt-in? Upper bracket can be fabbed, but those two lower rear bolts would seem to be the critical factor. I also just missed-out on a XT200 engine & complete electrics for $150 - would that have fit? I heard a rumor I have to stick with RFVC engines. Because of bolt-up? Or just an electrical connector problem? By the way, that's what type is in the bike. Eventually, I'll tear the engine apart if only to see what happened. But it might turn into a re-build. Any help is appreciated. Thanks.