Cylinder bores dropped out while heat curing engine paint.

[chuck hahn]

Bob. When the aluminum cools and contracts that what hold the sleeves in. They put that oring at the bottom of the sleeves because when the bikes running and hot there is actually a few thousands of a gap between the block and the sleeves that oil would migrate up if not for the orings. its the head being bolted down that keeps th sleeves from literally coming out of th engine while running due to the expansion of the block away from the outside of the sleeves.

Just heat the block back up and seat the sleeves and then let it cool is all thats needed here.

[Brendan W]

Looking at the first picture you might wonder if and how much varnish or carbon grit got under the liner flanges when they dropped back.
If I was looking at a skim I would also be thinking about getting them out again and cleaning up first.

[chuck hahn]

I did mention this was a good time to fully remove them and clean the block wells.

[05Astro]

I wonder if the bore sizes will change?

[chuck hahn]

No. Doesn't get hot enough to warp anything. Just 300 degrees or so and the liners will slide 0ut.

[Fjbj40]

Bob. When the aluminum cools and contracts that what hold the sleeves in. They put that oring at the bottom of the sleeves because when the bikes running and hot there is actually a few thousands of a gap between the block and the sleeves that oil would migrate up if not for the orings. its the head being bolted down that keeps th sleeves from literally coming out of th engine while running due to the expansion of the block away from the outside of the sleeves.

Just heat the block back up and seat the sleeves and then let it cool is all thats needed here.

When the engine is at operating temp there is no/zero clearance between the cylinder barrels and the cylinder cooling fins. They are an interference fit. You think the cooling fins get hotter than the barrels?

How would the cooling fins dissipate the heat out of the barrels if they are not touching the fins?

[roeme]

Bob. When the aluminum cools and contracts that what hold the sleeves in. They put that oring at the bottom of the sleeves because when the bikes running and hot there is actually a few thousands of a gap between the block and the sleeves that oil would migrate up if not for the orings. its the head being bolted down that keeps th sleeves from literally coming out of th engine while running due to the expansion of the block away from the outside of the sleeves.

Just heat the block back up and seat the sleeves and then let it cool is all thats needed here.

When the engine is at operating temp there is no/zero clearance between the cylinder barrels and the cylinder cooling fins. They are an interference fit. You think the cooling fins get hotter than the barrels?

How would the cooling fins dissipate the heat out of the barrels if they are not touching the fins?

Yep, what chuck said goes totally against my (albeit limited) understanding of our dry-sleeved, air-cooled GS engines.

[chuck hahn]

Then explain why the engineers found it necessary for the oring around the bottom of the sleeves?? And explain why on really high millage engine withhold crusty old orings theres always a little oil and some crud between the block and sleeves. The aluminums like a heat magnet and it absorbs heat from everything including the oil itself. Heat from the liners is absolutely absorbed by the block.


The fins air for dissipation of heat from air moving across them. The block is solid around the bores for maybe an inch or so and sucks heat off the liners lie a sponge in water. And there are gaps between each bore that also help cooling....some. I always spray well with the power washer when cleaning to keep the gaps between the cylinders free of road grime and other debris.

[chuck hahn]

Take some sleeves out oneday and youll find the grime around the outside surfaces.

[Agemax]

Take some sleeves out oneday and youll find the grime around the outside surfaces.

had this argument on another forum. turns out the "grime" you call it is actually installation lubricant, used when installing the liners on the production line.

[chuck hahn]

Looks like small black grainy stuff then after year of heating then.

[Fjbj40]

Think now. At the bottom of the cylinder it touches the case, convection works here. There maybe a little more expansion at this area of the cylinder. The engineers would add the o-ring here to ensure no oil leakage, all be it very very minor.

If the steel cylinders were not touching the cooling fins then heat dissipation would be greatly reduced. Pretty much non-exhistant.

Oil has more than one job, the second most important is cooling. It removes heat from the metal parts in the engine that don't have a direct cooling fin. It also absorbers heat from the gearbox. It then transfers this heat to the aluminum and then the airflow carries away the heat via the fins, whether they are on the cylinder, cylinder head or any of the case fins.

You said the cylinders do not touch the cooling fins, you are incorrect.

What do you think would happen to the cylinders if they had your stated "couple thou" clearance? I will tell you, they would flex like crazy. The amount of air flowing over the cylinders, when the bike is traveling, is capable of removing more heat than the cylinders produce. It has to be , otherwise the engine would overheat! That means the cylinders stay at a lower rate, smaller, expansion factor than the steel cylinders. Thereby maintaining the interference fit which gets rid of the heat. This is how an air cooled engine works. Just idle in traffic to long, see what happens to the engine.

Very little heat is absorbed by the block, sure there is some, but very little. Calculate the fin area on the block, properly called a case, vs the amount of fins on the cylinder and head.

Also, air cooling, when the engine is constantly having airflow over it is as efficient, and sometimes, more efficient than liquid cooling.

[GregT]

had this argument on another forum. turns out the "grime" you call it is actually installation lubricant, used when installing the liners on the production line.

True. While I don't use it when replacing sleeves, I've found similar paste in a Z1 barrel which had been resleeved in the US.

The O rings are there to prevent oil migration, yes. The liners are an interference fit in the block casting for about 2/3 of their length - the top portion. The lower third is a slip fit. This allows for differential expansion between the alloy block and the iron liner.
IMO it's not possible for oil to migrate as far as the head joint up the liners. But the barrel castings can be - and frequently are - porous. Suzuki would not have liked oil stains appearing on the finning hence the O rings.

[chuck hahn]

Maybe properly called a case in Canada. Parts fish calls them cylinders and shows the two lower halves as the crankCASEs. Here in the US we refer to them mas the cylinder or the block. Differences of opinion here obviously.

[Fjbj40]

That's what I said chuck, the lower engine is case, the cylinders are cylinders. You were the one that called the cylinders a block.

The rate of expansion of aluminum is greater at 300 than the steel barrels when there is no airflow. This is why in the oven the cylinders slide down the barrels when it is standing upright. My experience when I have removed barrels from cylinders anyways.

Certainly yes on porosity of aluminum, plus an old high mileage bike will have deteriorated seals thereby having oil in places a low mileage newer engine would not, leaks.