Ignition coils wired improperly? One cylinder not firing

[Larry Fine]

The rest are 40 years old, so unless you're going all new, used parts are fine.

[draser]

Ensure spring length is within specs per manual. Which spring broken, exterior or interior?

[Sterminare]

Ensure spring length is within specs per manual. Which spring broken, exterior or interior?

Im going to replace all the springs; I found a full set for not much more than a single inner/outer pair and I figure if one spring has broken, the rest are probably nearing the end too

But I will definitely measure them and confirm they're in spec before I install. The exterior spring is broken, clean shear about half an inch down from the top, it's loose I can slide the top half up and down. I can't see the interior one but I think its intact.

Side note, when the engine was running I was hearing a little tinking sound, sounded like a pebble in a glass cup, very quiet jumping around and making little noises. I bet I was hearing that half of the broken spring bouncing up and down.

[Pete in PA]

Wow! Mystery solved! Valve springs dont often break at all.

Now, What does the rest of the engine look like?  A 5k mile engine or a lot more?

Can you see the cross hatch perfectly on the cylinder walls or is it faded?

How much carbon on the pistons?

Might have to take the head to a machine shop for the broken studs.  Don't try to drill them, break off a drill bit or easy out, then take It.

The rest of the cylinders had 175 psi, better than my 92.  Points to a fresh engine.

Should be haulin in no time!

[Sterminare]

Now, What does the rest of the engine look like?  A 5k mile engine or a lot more?

The camshaft lobes have some dark spots, im wondering if they may have put on a 'new' head at some point. As there's orange silicone on every gasket besides the cylinder base to crankcase. Theres a fair bit of carbon on the cylinders and the valves but it's not very stubborn, much of it comes off with my fingernail or a dry paper towel. I didn't check for hone marks in the bore, right now im headed to get a C clamp and a socket to make myself a valve compressor.

Might have to take the head to a machine shop for the broken studs.  Don't try to drill them, break off a drill bit or easy out, then take It.

Fingers crossed. They broke with about an inch left sticking out of the block, thankfully, so hopefully i can hit it with a torch and get a vice grip on it and back them out. I have stainless steel replacements and new chrome cap nuts so it'll be nice and neat when its back together.

[draser]

The exterior spring is broken, clean shear about half an inch down from the top

Metal shavings in the oil filter/sump?? Camshaft caps look okay on the inside/journal side?

[Sterminare]

Metal shavings in the oil filter/sump?? Camshaft caps look okay on the inside/journal side?

Dont recall seeing any metal shavings in the oil filter but I didn't really look too close, didn't know I had an engine problem when I did that oil change.

Journals look ok I think, definitely have visible wear but not really any grooves that I can feel. Can kind of see here https://imgur.com/a/qRKUn2D

Working on cleaning off the old gasket(s) and silicone, taking the valves/springs out, and fixing those exhaust headers. Waiting on my head/valve cover gaskets to come in and my new valve springs. Hopefully this weekend or early next week I'll be putting it back together

[draser]

Good work, and finding a broken valve spring is news to me after restoring several vintage bikes. I bet the stubborn lifter correlates to the broken spring valve.
You seem to have gotten a good engine (less cyl 2) judging by the high compression, how's cylinder wall looking on 2, probably same as the rest?

[Sterminare]

Still haven't gotten to check the cylinder bores. But I got my valve spring compressor today; here's the culprit: https://imgur.com/a/7JLowjC

And a look at the valve seats. Second from the right is the one with the broken spring. https://imgur.com/a/kvr8hNM

Last photo in the above album is rust on springs and washers. Im noticing light surface rust on many of the springs and valve hardware. This is strange to me, how does that happen in a sealed oil-sprayed cavity.

This combined with the cylinders being in such good shape, and the placement of orange silicone, leads me to the theory: My engine is original 5600mi but a previous owner swapped the head with a higher mileage head at some point. Why you'd do that, idk, maybe it was cheaper than remachining after a valve burned or something. In that case, this head was stored on a shelf for some time before being installed and collected some rust. I have no way of confirming this though. But it makes me feel a little better that the whole engine may not be this worn. I don't plan on opening the crank case to confirm that though.

[Pete in PA]

Very fishy.  Why rust at such low mileage.
One other option is it sat for years with the valve cover off.
Wish the bike could talk.

I'd as lightly as possible lap all the valves, new valve seals, head gasket, etc. Should be good.

[Sterminare]

I'd as lightly as possible lap all the valves, new valve seals, head gasket, etc. Should be good.

That's the plan. Just waiting on parts now

[mollusc]

I'm not seeing any rust that would concern me.  It's surprising how crusty pieces can get inside a valve cover.
Is there much slop in the valve guide where the spring broke?

[draser]

Im noticing light surface rust on many of the springs and valve hardware.

My first 82 Magna was like that, had surface rust on valve train, tensioner, and on cylinder walls (had to get another block). No broken springs however. Bike's spent years outside with no cover.

previous owner swapped the head with a higher mileage head at some point.

Looking at your picture, the valves are sitting pretty high up in the combustion chamber, which indicates low seat wear and miles. Valves "sink" into their seats at high miles. Also, if the valve sealing ring (the mate ring on valve head) is narrow (around 1mm) that indicates low miles on the head.

I'd as lightly as possible lap all the valves, new valve seals

Since you're in there makes sense to replace the stem seals, regardless of mileage it's the old age that kills them. Lapping the valves is fine, and no... it does not affect the hardness of the valve as it is not case/surface hardened. The valve material is hard and the wear component is the seat actually, that how it's designed. And, if Allen Millyard does it then...

Actually, you should be able to see the cross-hatching on cylinder walls at this mileage.

[Sterminare]

I have all the intake valve sets out now, some of the springs have some pretty significant rust spots, im thinking they act as stress concentrations and caused early cracking/failure, so im glad I ordered a whole set instead of a single replacement (assuming they don't come in rusty too..)

The guides feel good, including the one with the broken spring. Very smooth movement and little to no rocking that I can feel with my fingers. So I don't believe that the valve was bent leading to the failure.

I have an overhaul gasket kit coming that comes with valve seals and everything so I'll be replacing everything that I can see

I've been cleaning up carbon off the valves, it's not particularly stubborn, but haven't touched the actual sealing surfaces- are these hard enough that it's safe to scrub with a brass wire brush? Or am I going to cut grooves across and ruin my compression? That goes for the valve seats in the head as well.

Good to know that theyre hardened all the way through.

[mollusc]

I don't usually use a wire brush on alloy heads.  Put it in the bath (or a disposable aluminium pan on the driveway) and hit it with spray-on oven cleaner instead.  Let it sit for no more than ten minutes or it will start to erode the metal.  Wash with water, and scrub with a Scotch-Brite pad instead of a wire brush.