Valve Stem Seals, or maybe throw in the towel

[Nessism]

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

[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

[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]

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.

[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.

[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.

[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.

[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.

[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]

Have the day off and hoping to get the new rings on. Replacing rings just because I’m in there anyway, and 38,000 miles. But new rings orientation has me a bit confused and I want to make sure I get this right.

Manual has me looking for a noticeable taper on the second ring:


original rings, no appreciable taper that I can see:


New rings profiles look identical to me. Tops are marked. One is definitely silver/shiny, the other dulll/black. I’m about 73% certain the shiny one goes on top, from the note in the manual about the top ring being chrome plated.






no issues with the oil rings, those are straightforward.

edit to add- the video below set me straight. The silver in the top/compression ring. The black is the second/scraper ring.

[Rich82GS750TZ]

Made good progress today. Was just about to pop in a new oil filter and fresh oil. When I was tightening the drain bolt, thought I felt the crush washer crush, then gave the wrench a little more. What I actually felt was the pan threads giving way. FML. Well, at least I have a spare oil pan that was already cleaned up and ready to go. Have a pan gasket on the shelf too. Spent the last hour or so scraping the old gasket. Decided to call it quits for the night and enjoy a beer. I could finish it up tomorrow, we’ll see how it goes.

I know there’s a new member here with the same bike who just did the same thing. Can’t seem to find a torque spec for the oil drain bolt in any of my references. Never had this happen before. Think I was getting tired and my built-in ugga-dugga meter was out of calibration.

[2BRacing]

The drain bolt threads on my 850 also stripped out.

Other members here reported using a special oversize bolt that cut it's own threads in the oil pan. Brian (bwringer) very kindly sourced one and posted it to me together with a few tubes of Honda moly paste for the drive splines.

That fix worked well and has been leak-free for some years.

[Rich82GS750TZ]

The drain bolt threads on my 850 also stripped out.

Other members here reported using a special oversize bolt that cut it's own threads in the oil pan. Brian (bwringer) very kindly sourced one and posted it to me together with a few tubes of Honda moly paste for the drive splines.

That fix worked well and has been leak-free for some years.

If you or bwringer knows exactly what that is I’ll buy one to fix this damaged pan, just to have as a spare. I had thought of doing some kind of repair in situ, but figured I’d have to take the pan off anyhow. Wouldn’t want thread cuttings left in there.

[Eli69]

"It's always somethin !"

[2BRacing]

If you or bwringer knows exactly what that is I’ll buy one to fix this damaged pan, just to have as a spare. I had thought of doing some kind of repair in situ, but figured I’d have to take the pan off anyhow. Wouldn’t want thread cuttings left in there.

It was a "+1 oversize" sump bolt in the standard 14 x 1.25 pitch. They are available in auto parts stores. Unfortunately I cannot locate my notes on that item now - apologies for not being able to provide you with better info.

I put grease on the bolt and turned it slowly in-and-out bit-by-bit until it was all the way in, and then removed it to clean the cuttings caught in the grease.