[Badapplesrepair]

Got this bike from my brother for $300 because it was completely destroyed. Had issues getting it going but after cleaning and tuning carbs for an ungodly amount of hours I got everything working. Bike was running fine but felt a little bit under powered but I figured I just needed to do a final tune on the carbs. Last mod I did was a block off plate on the valve cover after removing emissions stuff. Everything on engine is stock except for the aluminum radiator with silicone hoses, muffler which is a $30 Amazon muffler, and the intake filter which is a UNI foam filter. I did all the maintenance replaced all seals and o-rings and cleaned everything I could short of splitting the block. Took it to the beach on a Sunday and it ran good. It sat for a few months and when I went to turn it on it was spitting oil out of the muffler. It started up and idled fine but kept spitting oil, ran it around the block and even though underpowered it ran ok and reached about 45mph. I turned it off came back an hour later and left it idling for a few minutes. This is when I realized how bad the oil leaking out was, it literally emptied the entire contents in maybe about 5 minutes at idle. Extent of the issue didn’t become apparent until the oil pooling in exhaust pipes started spilling out where the muffler connected, I separated muffler from pipe and a large puddle of oil formed under the bike instantly. Added some oil and Tried to turn it on one more time which it did but it backfired and I finally decided to not mess with it unless strictly necessary. Compression test was really low, tried some tricks people suggested to see if rings where stuck but after a couple of weeks I gave up, compression tester was showing 18psi out of both cylinders. I figured it was odd but a clue that they both have same compression, issue must be in a common part? I have finally gotten around to dropping engine and taking a look inside. Everything looks good to me, no visible cracks in head or anything, valves appear to be sealing properly nothing really looks out of place to me other than the ridiculous amount of buildup on valves and pistons. There are also some spots of concern inside cylinders, maybe scorching? could it have been a bad head gasket? What non destructive testing can I do at home to check integrity of parts? Seals alone will run me about $200, a junkyard engine runs like $4-500 but it would also require checks and maintenance before I install. Not sure what to do or what Would be cheaper. Not sure if an issue but bolts that held block together seemed unusually easy to remove. Prior to all work performed engine ran, not perfectly but it ran, it was stolen and abandoned and i was sold what was found 3 days later, it didn’t run at the time. Any input is appreciated.