Vintage Dirt Bike Q & A

I was working on cleaning my mt250 motor for a rebuild. Once i removed the gasket material i noticed how scored the surface was, from the last rebuild. Should I just look for another right side engine case? And yes, your fingernail will catch on the scratches.

That's not too bad, it still has a lot of surface area and the scratches are parallel with the sealing surface rather than across it. I would run it, if it makes you concerned then maybe use Indian Head or Hi-Tac sealant.
It could be worse, your previous owner could have used a hacksaw:

How'd I fix that? A top secret filler above and below the gasket. I hope it never has to be removed, as it will be the biggest pain ever.

You are in very good shape there actually. I'd run a very thin bead of three bond 1104 (aka Yamabond, Hondabond, etc.) gasket sealant over the area for sure, but then I wouldn't think twice about it. The top end will still come apart next time without too much trouble.

Harold Honeycutt, a mechanical wizard, once saved me from base gaskets that were blowing out right at the transfers. "Just prick punch some dimples across the area, and that will provide enough gasket traction that she will hold together." Sure enough, worked like a charm. Maybe your previous guy was a sloppy scraper, but maybe your surfaces aren't exactly flat and maybe these scores are his way of getting it to work.

Goop up and ride,
Jon