Valve Stem Seals, or maybe throw in the towel

[KiwiAlfa156]

Rich, check the valve seat width.
Too wide a seat width and those carbon deposits to get stuck into the seat and keep the valve from sealing properly.
Too narrow a seat width will prevent valve head from transferring heat into the block.
Seat width should be about 0.040”

And a worn valve seat leaves the valve margin too thin and invites high temps that can melt the valve edge, much like yours looks.
Valve margin should be at least 0.02”.
Say, how far did you leave those HDs behind?

Engineers blue or even a marker pen works for checking both seal continuity and seat contact width.

 

[Rich82GS750TZ]

I've read-up some on this. For right now, it's a bit TMI all at once, a bit overwhelming. I will be seeking guidance when I'm ready. Want to do it right this time. Never lapped valves before. But I'm up for it if necessary.

 

[Rich82GS750TZ]

In case anyone wanted a better look at the broken valve. Everything is now bagged, tagged, and waiting for the snow to fly.

 

[93Bandit]

Wow! Too me it looks like a chunk of valve broke off, rather than burning off.

 

[rphillips]

I dun'no, It sure don't look like my burnt valves. I've got a CB1100F head out in the garage, with 2 burnt valves. It's still completely assembled and just looking you can't see anything wrong with it...

 

[KiwiAlfa156]

Just Google 'burnt exhaust valve' and look at the images. Or look at this

https://jaguarfuelinjectorservice.com/v12 engine burnt exhaust valves.htm

A serverely burnt valve, is the point they lose bits, the combustion pressure blows the edge of the soft (but not liquid) metal instantaneously out the exhaust port. It is a very sudden failure. A metal fracture will have sharp edges revealing the crystalline structure, or show evidence of tearing, the damage on a burnt exhaust valve if you look closely is rounded.


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[Rich82GS750TZ]

And so it begins. Since it’s intact with all its parts, l decided to work on the spare 82 head. It appears to be in really good shape. I ran a bolt through all exhaust bolt holes. All good there. Spark plug holes all good too. Valves have only a bit of carbon on them. I started using the HF compressor tool I bought on the springs and that was getting me nowhere fast. So I tried a method I’d seen in a video putting a socket over the valve spring retainer cap and whacking it with a hammer. Worked like a charm. Managed to keep all 32 keepers, both eyeballs, and nine of my fingers aren’t bleeding. I do intend to spend a good bit of time cleaning the head, measuring everything and trying my hand at lapping the valves. Haven’t bought new seals yet. No hurry. Got a shiny new red thing to ride.:tennis:

I have a question. The valve spring seats are still in place (second picture). They spin, but my weak magnet wouldn’t pick them out. And I didn’t want to try prying. I suppose if I’m careful not to lose them while cleaning, couldn’t they just stay there? Probably just answered my own question. As long as I’m careful.

 

[Nessism]

This gasket seems like a good deal. I can't find any OEM ones for cheap...

https://www.ebay.com/itm/256256214357

 

[Rich82GS750TZ]

Thanks Ed. That’s a much better deal at $52.15 than the OEM head gasket, which partshark has for $90.44 :-s I’ll be shopping for valve stem seals, base, head, valve cover, stator cover, clutch cover, and oil pan gaskets for this whole engine soon enough. Guess I know what to ask for for Christmas. Hmm, rebuild bits for the GS, or a top box for the Tiger.:-k

 

[KiwiAlfa156]

You can lift the valve spring seats out without damage with a pair of pliers. There will be a film of oil underneath them that is sticking them in place. They aren't an interference fit.or anything like that.

 

[Rich82GS750TZ]

Spring seats came out with out issue after some of the oil dried up a bit

Making slow progress over last few evenings. I lapped the valves. Got some Prussian blue dye and checked all. After a second go-round of lapping all valves and seats look more or less like the first pic below. First time doing this and learning. Pretty happy so far.

I have these seals in my eBay cart. Only ones I found that actually mention viton. I’ll get these unless someone has a better idea.
https://www.ebay.com/itm/300785685234?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=-nkPeINbTN2&sssrc=4429486&ssuid=EK7fcRW9Q5y&var=&wi dget_ver=artemis&media=COPY

I have a question about installing the seals. Various videos show 2 different ways. Clymer manual says to push or drive the seals into place then insert the valve stems up through from the bottom through seat and seal. I’ve seen videos where they inset the stem through the seat first then install the seal over the stem. Is one way better? Does it matter. Dumb question?

edit: this seems like a good idea:

Anyway, thanks for the help. We’ll get there.

 

[Grimly]

Conscious of the danger of damaging the seal lip, I inserted the valve into the head, covered the end of the stem with a bit of polythene that's long enough to cover the collet cut-out, then, with plenty of lube, slowly pushed the seal over the stem and down onto its seat. Not sure about your head, but mine has a seating recess at the base of the shoulder where the seal sits.
I used long cup-nosed pliers to seat the seals properly.
After that, easy enough to re-install the springs and collets.

<edit> pretty much like the video shows.
Frankly, anyone who advocates fitting the seal to the head, then just ramming the valve up through it, is an idiot whose advice on other stuff is probably just as flawed.

 

[Rijko]

Frankly, anyone who advocates fitting the seal to the head, then just ramming the valve up through it, is an idiot whose advice on other stuff is probably just as flawed.

why is that, Grimly ?

 

[Grimly]

why is that, Grimly ?

Lip damage, of course.

 

[Rijko]

I personally like to install the seals without the valves installed.

That way i have a better feel for the oiled up seal, i can feel the seal plop in the valve guide groove.
With better feel i mean compared to using pliers.

Remove the spring from the seal, oil the valve stem (GS valves do not have threads like in the movie shown earlier)
and push the valve through the seal.
No way that can cause damage to the lip.
Next, install the spring.

What's in this procedure that you find so risky ?

 

[KiwiAlfa156]

Lube is the best way to prevent seal lip damage. The valve stem end is beveled and collet retaining grooves are smooth and not sharp enough to damage the seal unless the seal is old, cold and hard. Best lube to use is molybdenum engine assembly grease. Factory manual says to use it. Assembly lube liquifies on start up and moly has strong anti-seize properties on metal on metal contact which is what you want until engine oil can reach where its needed. Stem seals wipe the valve stem but just enough oil is left on the stem to lubricate it. Just be gentle pushing the stem through the seal.

 

[Rich82GS750TZ]

Thank you, gentlemen. Seals ordered.

 

[Grimly]

Remove the spring from the seal, oil the valve stem (GS valves do not have threads like in the movie shown earlier)
and push the valve through the seal.
No way that can cause damage to the lip.

Utterly wrong - it's very easy to damage the lip that way and you won't know it until you've put it all back together and on the road.

 

[Grimly]

The valve stem end is beveled and collet retaining grooves are smooth and not sharp enough to damage the seal

Another piece of wrong-headed advice.

 

[KiwiAlfa156]

Another piece of wrong-headed advice.

Were you traumatized by an unfortunate stem seal incident? Asking for a friend.