I know this question will probably sound a bit dumb, but I’m just wondering if it’s possible to pressurize a 4 stroke engine like a leak down test and check for where oil might be leaking by spraying around things with soapy water? I have quite a bit of oil leaking from the top of the cylinder head on my 81 XT 250. I’m thinking it must be the o rings in the valve adjustment caps and cam cover, but would like to be sure before spending the money and just tossing parts at it. Thank you for any input.

Ryan

Best way is probably clean off the oil and look for the leak.  Dusting suspected areas with flour or baby powder can help.

You can also get UV dye to put in the oil and then search for leaks with black light.  Most auto parts stores have it.  Dye is under $10.  If you have a black light you're set or you'll need to get a blacklight.  You can get a flashlight or with Halloween it shouldn't be hard to get a blacklight bulb.  They might have a kit with everything...  but I have a blacklight flashlight I use for scorpion hunting so I never needed to get one.

Tappet cover Orings on those go hard & flat & leak like a sieve. So does the seal on the valve lifter arm at the exhaust valve. Anything like that will leak when old & overheated possibly. Even the Orings sealing the rocker shafts into the head. If it's coming from the head gasket then no easy way out except go in there or clean it off & carry on until it's oiling your shoes. I'll find a pic of my worn out cam just for a laugh. Was a TT250 but same horse.
Found it haha. Had no power, hardly drag itself along. No rattle as clearance it set on back of the cam. Took me a little while to find where the horses were hiding. 

Was it hard to find a new cam and rockers for that bike? I’ve read that a Yamaha warrior cam fits the xt 250? But not sure if rocker arms would fit too. I ordered all new o rings for those covers. Appears that is where quite a bit of oil is coming from.

Mate was right into these models & had a spare cam & one rocker. I was mean't to give him this one back to rebuild--years ago--must do it. He works in a camshaft rebuilding business--if there's any of that going on these days amongst other things they do like building stock car motors.
I'm sure i've heard stories of warrior cams but googling might come up with info. Maybe not much use doing things like that without more compression or a big bore kit if they're out there. May as well find a stroker crank plus big bore kit & go for broke--& hope it doesn't break lol. Bike looks too nice to do that too. Love the color--or [colour in nz]. Cheers.