engine condition - good, bad, can be lived with?

bike: 1983 kz550c4 ltd
what constitutes a "good/acceptable" or "better replace that" cylinder/crankshaft section?

after having a hard time starting the bike & having it make a rather loud clacking noise from the left side last week i figured it was a good time to pull the carbs & have a look at them - and i found 2 of the 4 slide flappers were missing (2 and 3) but #2 appears to have recently been sucked into the engine. figuring that since the carbs were off this would also be a good time to check the engine out & replace the gaskets i've taken off the cylinder head, camshafts, & cylinder/valve section down to the crankcase top.

in the 1st pic you can see the 2 pieces of the carb slide flapper i found in #2 (#1 is on the left) & what the bottom of the valve end looks like - one piece is actually stuck in there, the longer piece on the right side can simply be removed.

right side seems "ok", though carbonated(?).

what i'm wondering is whether or not i should find some parts in better condition & replace what i have or would cleaning up what i have be sufficient to get another 5 or 10k before replacing the crankcase, cylinder section, or camshaft section (camshafts appear visibly ok). or none of the above & some other approach?

picture 2 is the crankcase top (#1 on left)

picture 3 is right side, cylinder bottom end

picture 4 is what it used to look light at night before i took the carbs out & most of the engine.











regards,

To test the valves you can put the spark plugs in the head, flip it over and fill the chambers with gas or solvent. If it leaks out then the valves aren't sealing fully. I'd take the valve train apart, inspect everything and replace the valve guide seals even if it's not leaking.

I usually do a compression test to check the state of the motor before taking it apart, but you're already past that. You might consider taking the cylinders off so you can measure the cylinder diameter, connecting rods, pistons, etc. You need a t-gauge and micrometer set. It cost me about $80 for a pretty complete set. There is a whole engine maintenance section on how and what to measure in the service manual. It covers every nut and bolt.

Take apart, clean combustion chambers by drill and wire brush, remove pieces. Lap valves to see how good/bad valves and valve seats are.
If piece is under valve, valve is possibly bent. Good head is probably dirt cheap on ebay.

You can fill the intake and exhaust runners with gas to see if they leak. But by the way it looks they probably will. If it was me i would pull the valves being careful to keep each valve in its original location. I do the same with the buckets and springs and keepers, i know those could be moved, but i like them to go right back where they came from. Also did you check your valve clearance before disasembly? It would make it easier knowing what you needed and where. Also did you mark which shim sizes go where? If you do end up getting a new head or valve job it will change, but if you just clean it up and lap the valves and it might be ok.

thanks for the responses. i've been a little busy this & week & am trying to make time to get the valves out. hopefully i can squeeze that in tomorrow to see what state they're in. i've looked on ebay for a new valve section & am a bit surprised to not see a lot of them, and what is listed tends to be of the rust bucket variety. hopefully there won't be too much, if any, valve damage. now if i can just get those carburetor throttle arm screws out without damaging them ... those are in tight.

OK ,let me see if I have this right.
Your 83 kz550 ate 2 of your carb butterflies?
Plus the 4 screws that hold them to the shaft?
Or did the screws just snap the heads off? A big sneeze or a backfire or something that you remember?
WOW !!
and
OUCH !!