So,
Long story short, I made (what is now) a regrettable purchase of a 2001 Kawasaki KLX300 with tapping noises coming from the engine. Additionally, the engine is low on compression and is burning oil. A video of it running is available here https://drive.google.com/open?id=1M14Bl2bOE7xZRq-o4XpqYXePEKV7cwEX, along with some photos which were too large to upload.
The previous owner provided receipts for an exhaust cam replacement, so I reached out to the shop where it was done to see if they knew what was going on. The shop owner told me something along the lines of "both camshafts needed doing, but due to budget, [the previous owner] chose to do only one'. He said "it'd need the intake cam replaced, and ideally a new cam chain because the one on there is stretched."
I then got the opinion of a second mechanic, who believed that the noise was most likely piston slap or rod knock. While the first mechanic has seen inside the engine, whereas the second has not, I'm inclined to say that the first mechanic has no idea what he's talking about, because when I called him back, he seemed oblivious to the other issues.
So, after two very different opinions, I decided to find out for myself. Over the weekend, I disassembled the top end of the engine, and I'm disappointed to say that nothing yelled out to me.
Inside the engine
While there is evidence of wear on the intake cam, there is no excessive rounding of the lobes. The intake valves look more recessed than the exhaust valves (see link for photo), however, that seems pretty meaningless to me in the context of the noises coming from the engine. (thoughts??)
After reading some forums, I am now aware that early 2000's kawasakis had inherent problems with their automatic chain tensioners sticking and not tensioning the chain properly, but the chain seemed very tight to me when I took off the valve cover and checked it.
In addition to the above, the cylinder has no aggresive/irregular wear on it, and as far as I can tell, there is no axial play on the piston or rod. I've never rebuilt an engine, however, I am aware that there is a service limit to lateral play between the rod and crank; and in my case, it does seem to be wider than any feeler gauge would be (I will check this). (thoughts??)
In the video, you will see that the tapping noise is more pronounced on the right side of the engine (which is where the timing is), but again, I'm not sure what this might mean in context of the above.
Any thoughts on what is going on and/or what my next steps should be?
...I thought that now would be a good time to ask, before I commit to taking apart the rest of the engine and potentially look past possibilities that are right in front of me. I am determined to fix it on my own - because that's my usual approach to any problem, and it's way more fun that way - but would greatly appreciate any thoughts/advice.
FYI: Low compression diagnosis - Before I opened up the engine, I did a cylinder leak test by feeding compressed air into the engine with the piston at TDC using one of these https://toolswarehouse.com.au/products/lisle-19700-12-flexible-hose-valve-holder. I managed to hear/feel air coming out of the crankcase, telling me that I'm in need of a new piston/rings. I wish the rest was that simple...
