new head gasket on GS550 results in oil dripping from front 10mm screw

[DimitriT]

So far so good as far as leaks go. It's not insured/registered yet so I can't really go for a long ride but a few launches up and down a country road feel really strong. Much stronger than with the old sleeves.

[DimitriT]

So I reassembled it with the OEM head gasket and the thicker o-rings. I also applied a bit more sealer around the rectangular o-ring and a light coating of sealer on the outer edges of the mating surfaces of the head gasket. Since I didn't remove the block, I didn't disturb the base gasket so I hope that doesn't give me trouble.

Compression checks out: (130, 120, 120, 125, dry and cold) it used to be (80, 60, 85, 85) before the new sleeves

I prepped the base gasket by applying a light coat of general purpose grease on both sides everywhere, and some sealer on both sides of the corner portions which contain the oil galleys - I've never had a leak with this prep and the old gasket comes off without the usual ball-busting).

So I still went ahead and ordered a NOS OEM head/base gasket in case the reuse attempt fails. I ran the bike briefly and no leaks yet. Next I'll sync the carbs again and do some road testing.

My plans for this bike are to transport it to Florida and keep it at my parents house for use when I am down there. I've had this bike for 16 years and put over 50k miles on it. Most likely it will go into the estate sale.

[DimitriT]

Am I understand correctly that you reused the original OEM gasket that came on your bike 40 years ago?

No, I found a new old stock OEM on ebay.

[Nessism]

Am I understand correctly that you reused the original OEM gasket that came on your bike 40 years ago?

[DimitriT]

So I tore into it today and here's what I found:

1. the surfaces are clean, flat and smooth. I mean you cannot tell there's new sleeves in there.

2. since I was using a NOS OEM gasket (I measured it at 1.25mm thick, BTW) I added the four o-rings in the corners, plus the middle o-ring.

3. somehow I ended up with two sizes of corner o-rings: 1.15mm thick and 1.45mm thick.

4. one of the corners (cylinder #1, front) had a thinner o-ring - aha, there's your problem.

Now the MLS gasket I have is 1mm thick and maybe those thinner o-rings were meant for that type of gasket, I don't know. But using the OEM gasket with the thin o-rings is never going to seal.

[DimitriT]

That's a MLS gasket.

ok so the OEM gaskets don't have that composite core and they are stamped with "TOP"?

For MLS gaskets, which side goes up?

[Nessism]

That's a MLS gasket.

[DimitriT]

So what do folks think of this type of head gasket:

https://photos.app.goo.gl/TLq3csJxjiSCcg7h7

I had this left over from a gasket kit. It looks like two pieces of steel with a black composite material in between. It measures 1mm thick. The OEM measured 1.25mm.

That extra .25mm may be why it's leaking even though I used the o-ring.

[GregT]

Just the block should suffice.But if you've used an MLS head gasket, I wouldn't re-use it as you will almost certainly have stretched/indented areas of it already - and it may not seal again.

[DimitriT]

So do I need to have both the block and the head surfaces skimmed? Or is it enough to just do the block since I replaced the cylinder sleeves.

I re-torqued after running up to temp a few times and got 3/8 of a turn on a few studs. It actually fixed the leak at that front 10mm bolt but now I noticed another major leak between #1 and #2. So I will take it apart again and do it right this time.

[Nessism]

Those MLS gaskets require a very clean and flat sealing surface in order to seal. As mentioned, I don't think the square O-ring should be used with the MLS gasket.
Changing the liners requires the surface to be decked afterwards. I'm not sure what the deal is but the liners/cylinder have different colored dots on the bottom so I think they are a graded fit of some sort.

[fastbysuzuki]

You need to make sure the head and cylinder mating surfaces are flat more so if you use the multisteel head gasket if so the cam chain oring/gasket is not required

[GregT]

Hmmm.. When the top surface is machined, do they do that with the liners in the block? I guess they must otherwise the liners would sit proud of the surface.

Correct. It's the only way of ensuring everything is level.
Take it to a machine shop and ask for a very light levelling cut on the top surface. They'll probably only take about .005in off which won't change cam timing enough to bother with.
I'd pick that at least one of the inner cylinder liners is standing slghtly proud of the gasket surface.

[DimitriT]

And again - you changed the sleeves ?

If this has been done it's imperative to have the top surface of the block skimmed flat.
Even if you think it is already flat.

Hmmm.. When the top surface is machined, do they do that with the liners in the block? I guess they must otherwise the liners would sit proud of the surface.

[DimitriT]

You changed the sleeves ??. If you mean the cylinder liners, are the replacements flush and all flat on the gasket face.

Yes they appeared flush.