GS 1000 S1 vs S5 cylinder head

[John Kat]

I took a few pictures of my GS 1000 ST cylinder head and compared them to a GS 1100 head.
Allthough the GS 1000 ST is equipped with the VM 30 SS carbs vs the CV carbs on the 1100 the intake part is strictly identical with a bore diameter of 33 to 34 mm.
The carb boots must be different but I didn't have the CV boots on hand to compare?
On the exhaust side we can clearly see the "D" shaped port on the 1100 head compared to the traditional round port on the 1000.
Here are the pictures with the 1000 in silver and the 1100 in black:

[rustybronco]

I don't understand what you are trying to ask?

[mrbill5491]

Ooookay, and?

[John Kat]

I don't understand what you are trying to ask?

There is no question
I remember seeing a post that asked to compare cylinder heads as it's a potential upgrade.

[hampshirehog]

Are there any differences in the size / shape of the combustion chamber?

[Nessism]

The 1100 combustion chamber is larger. I don't know how much though.

[John Kat]

Are there any differences in the size / shape of the combustion chamber?

The difference must be minimal as the "depth" of the combustion chamber is 22 mm on both.
The measurement is between the lowest point between the two valves and the gasket surface of the cylinder head.
The O.D. is 70 mm on the 1000 and 71.5/72 mm for the 1100 corresponding to the piston diameters.
The C.R. should be different if you look at the pistons: low dome on the 1100 and high dome on the 1000.
Maybe because the bike is a GS 1000 ST or maybe there are the same due to the larger squish area on the 1100?
Both are manufactured by ART.

[TeamDar]

What about the diameter of the combustion chamber in the heads? Are they the same?

[tkent02]

Are the GK pistons, combustion chambers and compression ratios the same as a regular GS1100G?

I'm just wondering as every GK I've ridden is very slow compared to every 1100G.
Even considering the extra weight they seem much too slow.

[John Kat]

What about the diameter of the combustion chamber in the heads? Are they the same?

No,as I mentioned earlier the diameter corresponds to the piston size i.e. 70 mm for the 1000 and 71.5 to 72 for the 1100.
I could try to draw the profile of the combustion chamber to illustrate the squish area if there is any interest?