Engine spewing oil

[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.

[Chicagobob]

What did you block off on the valve cover? There’s no “emissions stuff” there, only the breather, which you need to have to relieve pressure in the crankcase. Without it, the engine will pump oil out of every crevice, especially if it’s overfilled, and into the airbox, where it will leak out the drain hose and the joints. Also, performance will be compromised because the pistons will have to push against the air trapped in the crankcase. Run the engine with the oil fill cover off and see how much air blows out of there. Shouldn’t be much.

I don’t know why your compression readings are so low, but I would at least make sure your breather system is operating.

[Badapplesrepair]

I blocked off the air induction valve on the valve cover. Some people said online they eliminated it when they removed all emissions stuff from their bike since the hose on top leads to a bypass valve or something. I might have read bad info or I could be mistaken in the way I interpreted the information and maybe this is the cause of my problems? The one on there was not fully blocked off but it had a piece of rolled up rubber tightly wound and plugged in there so I assumed nothing was getting by anyways and purchased a block off plate from eBay. The bottom breather that was leading to air box was in tact and there was no oil inside air box, it was one of the things I was advised to check when I first started having issues. On another note, do you know where I can get a head gasket for a little cheaper? It’s going to cost me over $100 just for new gaskets

[Chicagobob]

I could be wrong, but I’d check it out with the service manual, at least.

[CZroe]

These petcocks are known to leak through the carbs and cylinders and into the crank case. Happened to me even after installing a brand new petcock. Parked it for years and an entire tank of fuel ended up flushing through the crank, diluting/displacing oil. Ultimately it all drained down to where the clutch cable enters but presumably could have been higher at some point. Could it possibly end up in the exhaust instead? Not sure, but it might explain the condition of those cylinders.

[Triple Jim]

Originally Posted by CZroe

These petcocks are known to leak through the carbs and cylinders and into the crank case.

Agreed, but a leaking petcock alone can't get fuel into the engine. The carb float valves have to also be leaking, so both need to be checked if leaked fuel is suspected to be the problem.

[CZroe]

Originally Posted by Triple Jim

Agreed, but a leaking petcock alone can't get fuel into the engine. The carb float valves have to also be leaking, so both need to be checked if leaked fuel is suspected to be the problem.

Right, but it’s happened on many bikes that were seemingly running well when parked… where no one noticed an issue in the carbs. Maybe the fuel going bad in the carbs consistently gums up the floats and eventually lets fuel past.

[Badapplesrepair]

I thought it could have been the same thing. It’s why I first changed the oil and then did a compression test. My original theory was that maybe all that mess caused some of the rings to seize which is why I was getting low compression but since I was getting very low compression on Both I assumed maybe something in the head had broken. After taking it apart and looking at everything doing a visual inspection and speaking with the previous owner I have come to a completely different conclusion, failed head gasket. Sounds unlikely but hear me out, previous owner complained of cooling issues which is why I rebuilt the cooling system. Previous owner also complained of a small leak around the valve cover but had no idea from where it was coming from. Outside the engine on the exhaust side there was a mixture of old caked oil with fresh sticky oil right under the exhaust ports. Inside engine when first taking things apart we can see that the block, the head and the head gasket has caked thick oil deposits suggesting an on going oil leak from head gasket. When inspecting the inner components I can see that on the exhaust side there is heavy amounts of burned oil caked on to everything and what looks like caked half burnt oil coming from under the head gasket which looks like it connects to the oil that was leaking out from the gasket. I have concluded that gas did leak into the oil and since the head gasket was already failing it caused it to dump tons of oil into the cylinders which did not fully ignite and came out the exhaust and out the mufflers. I will be cleaning everything up really well checking tolerances and reassembling with new gaskets. Once done I will test compression before going any further.