Valve Stem Seals, or maybe throw in the towel

[storm 64]

Don't forget the dowels. Seems like a thing you wouldn't forget doesn't it? You would think that......
Yeah, I forgot the dowels.

I got you beat.
I was assembling the valves in a cylinder head.
I was almost done when I looked to see the valve stem seals still in the package sitting on the bench.

[Rich82GS750TZ]

Most parts arrived today. Waiting on the base gasket yet. I will gap and install new rings, hone the cylinders, then I can start the rebuild. Hope to get a lot done this weekend.

[Rich82GS750TZ]

Don't forget the dowels. Seems like a thing you wouldn't forget doesn't it? You would think that......
Yeah, I forgot the dowels.

Yep, remembered those too. Any damaged dowels (had a few) noted during disassembly have been ordered. Big ones between base/barrels, barrels/head, head/valve cover, and a couple of the little ones on a cam cap or two.

[KiwiAlfa156]

Darryl, thanks for the thought, and the explanation of why those are there. I appreciate any reminders. Yes, I’ve already removed those big orings that live in the channel around the base of each cylinder. They’re on order along with the other wear items: gaskets, copper washers, orings that fit around some head bolts, piston rings, cam chain tensioner gasket, tack drive orings, etc. All those things were new 11,000 miles ago when I rebuilt this top end. At that time I did not lap valves and replace piston rings. This time, I am.

Rich, it sounds like you've got it well in hand. Good work, my friend. I'm enjoying the thread.

[Eli69]

Don't forget the dowels. Seems like a thing you wouldn't forget doesn't it? You would think that......
Yeah, I forgot the dowels.

[Rich82GS750TZ]

The other thing to be aware of, is the o-rings on the bottom of the cylinder liners. If originals, they most certainly will be hard and brittle.

The liners are fixed at the head mating surface by a step on the outer upper edge of the liner and a corresponding rebate in the alloy clamped down by the cylinder head. At the bottom the liners 'float' in the alloy finned barrels. This is to accommodate the different coefficients of expansion between the iron liners and alloy barrels as the engine heats up and cools down. The o-rings sit in grooves in the bottom of the barrels to seal the the liners to the barrels but allow them to slide under expansion and contraction ensuring the liners don't distort. The o'rings are to stop oil getting between the liners and the fins.

I've heard different explanations of why this might be a problem.

Some say the oil can make its way to the head gasket and leak out the joint, other's that the alloy in the fins is porous and can also leak/sweat oil though to the outside of the fins. Some say it can interfere with heat transfer from the liner to the fins, but I find that unlikely (think oil-cooling). Some air-cooled engines don't have them, but Suzuki put them there. So I'm banking there's a reason why.

Darryl, thanks for the thought, and the explanation of why those are there. I appreciate any reminders. Yes, I’ve already removed those big orings that live in the channel around the base of each cylinder. They’re on order along with the other wear items: gaskets, copper washers, orings that fit around some head bolts, piston rings, cam chain tensioner gasket, tack drive orings, etc. All those things were new 11,000 miles ago when I rebuilt this top end. At that time I did not lap valves and replace piston rings. This time, I am.

[KiwiAlfa156]

The other thing to be aware of, is the o-rings on the bottom of the cylinder liners. If originals, they most certainly will be hard and brittle.

The liners are fixed at the head mating surface by a step on the outer upper edge of the liner and a corresponding rebate in the alloy clamped down by the cylinder head. At the bottom the liners 'float' in the alloy finned barrels. This is to accommodate the different coefficients of expansion between the iron liners and alloy barrels as the engine heats up and cools down. The o-rings sit in grooves in the bottom of the barrels to seal the the liners to the barrels but allow them to slide under expansion and contraction ensuring the liners don't distort. The o'rings are to stop oil getting between the liners and the fins.

I've heard different explanations of why this might be a problem.

Some say the oil can make its way to the head gasket and leak out the joint, other's that the alloy in the fins is porous and can also leak/sweat oil though to the outside of the fins. Some say it can interfere with heat transfer from the liner to the fins, but I find that unlikely (think oil-cooling). Some air-cooled engines don't have them, but Suzuki put them there. So I'm banking there's a reason why.

[Rich82GS750TZ]

Well, the second gasket was cancelled and refunded by the seller, claiming “we couldn’t find it”. So I just bought this one. Hope this one works out. 3rd time’s a charm, right? It is OEM NOS.

https://www.ebay.com/itm/234828373740?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=chQUJofoR8O&sssrc=4429486&ssuid=EK7fcRW9Q5y&var=&widget_ver=artemis&media=COPY

[Nessism]

Base gaskets are critical. OEM only, in my opinion.

[rphillips]

May be OK for some other gasket, but I wouldn't use it either. Just waaay too much to do if need to re-do it.

[Rich82GS750TZ]

Thanks Bob,
Re-reading what I wrote. this is the only logical answer. Ordered.

[Baatfam]

So, I got this fiber/paper base gasket from eBay. It was packaged folded in half and the envelope bent in half longways. Out of the package, no creases or tears. But not sure if I should go ahead and use it, probably not worth the trouble to send back for $15 I spent? I did not leave a positive feedback.


or order this one?
https://www.ebay.com/itm/294802954527?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=6-YLDnaeQ4a&sssrc=4429486&ssuid=EK7fcRW9Q5y&var=&wid get_ver=artemis&media=COPY

I wouldn't be comfortable with the folded base gasket. Too much to redo if it doesn't work.
If it was my choice, I'd go with the OEM eBay one. (Only one left!)

[Rich82GS750TZ]

So, I got this fiber/paper base gasket from eBay. It was packaged folded in half and the envelope bent in half longways. Out of the package, no creases or tears. But not sure if I should go ahead and use it, probably not worth the trouble to send back for $15 I spent? I did not leave a positive feedback.


or order this one?

https://www.ebay.com/itm/294802954527?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=6-YLDnaeQ4a&sssrc=4429486&ssuid=EK7fcRW9Q5y&var=&widget_ver=artemis&media=COPY

[Rich82GS750TZ]

No Cipher. That is definitely a rag.
No towels thrown in, yet.

[Cipher]

All parts ordered, should be here before Xmas. I have vacation scheduled the whole last week of December. So with any luck I’ll be going for a New Years Day ride on a re-re-built GS. We’ll see how it goes. I may be able to get the valves back in the head this week.

I hate scraping gaskets, but at the same time find it very satisfying work. Complete focus on getting it all, and on not gouging the mating surface. Of course, after I took this picture, I dropped the razor blade down the cam chain tunnel. That really got me sweating til I eventually retrieved it with a small needle-nose pliers. I had a rag in the piston hole. No idea why I didn’t put one in the tunnel. But, with that, all parts are at least clean and ready for rebuild.

Hey is that a towel we see.