Cracking open an engine for the first time, what do I check/look for/replace?

[Ncstatecamp]

Ive just "finished" my lil 5000 mile jaunt around the eastern seaboard on my 750k2 and I have an oil leak. Its more then likely the pucks that go over the studs below the rockers, but while I have the engine out and the cover off what else should I change/measure/look at/service? I know the old saying is if its not broken dont fix it, but theres something to be said about preventative work too.

this is my first time diving into an engine, but Ive rebuilt the rest of the bike so I'm fairly certain I can handle it. Yes I do have the manual as well, though I can't always follow it very well.

Things I think I should check/change but tell me if Im wrong.

Cam chain - not sure how to check - anybody got suggestions?
cam chain tensioner - more then likely replace
piston heads- at least clean, not sure how to check
rings - more then likely replace?
gaskets - im assuming pretty much all have to be replaced (base, head, cover, any more?)
stud pucks - replace all?
valves - not sure...
valve springs - I can just measure I believe?
cylinder walls - measure but not sure what to do

any more suggestions on things to check?

I wasnt planning on ordering parts til I get it open and know what I need

what are the little white rings between the fins on the front? a couple have expanded due to oil saturation, not sure what they do...

as Ive mentioned it a 72 cb750. I received the bike as rolling frame and engine, which Ive spent the last 1.5 yrs restomoding. Previous milage unknown, except the 5k I put on it - which besides the leak ran like a champ. The previous pressure test ran 120 psi across the board but I'll be doing another before I crack it open. I do not wish to split the case.

 

[JGHiggins1]

I like to remove and lap the valves to make sure they have a nice tight fit. I have had luck cleaning the tops pf my pistons with marvel magic mystery oil and a stiff brush this method also works well for the inside dome of your head. If your cylinders are smooth and within normal limits I would just de glaze them and call it good. Best of luck I hope your journey goes well.

 

[Ncstatecamp]

I like to remove and lap the valves to make sure they have a nice tight fit. I have had luck cleaning the tops pf my pistons with marvel magic mystery oil and a stiff brush this method also works well for the inside dome of your head. If your cylinders are smooth and within normal limits I would just de glaze them and call it good. Best of luck I hope your journey goes well.

So I can just lap my old valves and reinstall? What about valve guides, piston rings etc?

 

[JGHiggins1]

Check your valve guides to make sure they are in speck. If they are roll with them. As for the valves themselves if the shafts are straight and nothing is warped cracked or too badly worn you can keep using them. If you are willing to drop the cash on them you can have all new valves guides and springs installed along with recutting the valve seats. I forgot to mention new rings. It is a good idea to replace them while the engine is apart. If your piston is within normal limits leave it be. If you want to sink some cash into it you can always have the cylinder board out and put larger pistons in. but make sure you have your oversize pistons and rings in hand before you have the cylinder done. I made the mistake once of not having pistons and rings both in hand before I had the cylinders done. Received my new pistons with a note informing me rings for this size piston were no longer available.

 

[Ncstatecamp]

Well I did a compression test and Its pretty much 90's across the board. So definitely rings and at least lapping valves. The one thing I'm truely worried about in all this is the reassembly with correct timing. Can somebody give me a step by step on that?

 

[alzcbz]

You may want to add a teaspoon of oil to your cylinders and redo your compression readings. If your readings go up, its likely rings causing low comp.
It's a good idea to lap the valves while you're in there, but it also helps to know where the low compression is coming from.
Have you done a vale adjustment recently? Is the lash set too tight? That will give you lower comp as well.
A manual should give you a step by step process of timing.

 

[Ncstatecamp]

For these bikes a full run down: timing, cam adjust, tappet, etc is recommended every 3k. I did one at 3.5k on my trip so everything should still be within spec. I will be doing a pressure test once I get it on my bench and that'll tell me what's causing the most leakage, be it: rings, or ex/in valves.