Since my Savage is running about as well as I can make it run, I picked up a basket case Honda for $200. What's the old saying? Nothing is more expensive than cheap? The engine was shot. It was supposed to be able to turn over, but it was locked up solid. I took it down to the cases. Turns out it had broken both an intake and exhaust valve on the #3 cylinder, plus a broken rod. I don't think I've ever seen a piston rod break on the piston end. Even with that removed, the bottom end wouldn't turn over. It turned out to be full of water! It might have been in the floods from last year. Anyway, parts for old Hondas being fairly plentiful, and fairly cheap, I found another engine with nearly the same mileage (30-32,000 miles) For $650 delivered, so a lot, but not TOO bad. I've been gathering the parts I need to get it going. Anyway, if anyone here is interested, here's the link to my not-too-in-depth posting about it on another forum.

https://hondaforum.com/forum/cruising-standard-23/new-old-bike-85-nh-650-a-17944
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I stopped tearing it down when I got to the bottom end, but I had to cut the cam chain to get the head off. I really don't know what happened to the engine. I stopped disassembling when I pulled the crankcase drain plug and lots of rusty water came out, followed by maybe a quart of old oil with little sparklies in it. I might get around to splitting the cases eventually, just to see. The broken rod was lodged too low to see, and the chain couldn't be moved around enough to get the sprocket bolts out.

I've done several SOHC Honda 4s over the years. In fact, I used to look for CB750s that were for sale cheap, because 9 times out of 10 they had stretched the cam chain (1st gen were about the same as a bicycle chain.) trying to pull wheelies, etc. The chain would get so loose it would drag on the bottom case, and the owners thought they had serious bottom-end problems. Whenever I found one like that, I'd explain what the noise was and offer to swap the cam chain. Nobody ever did that; they just wanted me to give them $500-800 and they'd walk away.
The Nighthawks after '83 were supposed to be maintenance free. They even have self adjusting hydraulic tappets, so valve adjustments were few and far between.
This is when I unloaded it.

I know, nothing is truly maintenance free...

A better shot.