best and max. compression ratio to GS street bike?

[Addy Leung]

For a street bike GS1100, what is the “maximum and best” compression ratio?
The modern bike they are reach to 12.5:1, like the GSXR1000, R1.
Could our GS also be like that?

[salty_monk]

I don't think so.... you would get detonation. It can probably go up above 10:1 though I would think.
Ray can probably give you an idea what's safe...

Dan

[posplayr]

Check this thread

Scooter is running 12:1

I currently have an 1100E with WebCams 348 lift, 1mm oversize valves, ported head, 1260 kit at about 12 to 1. The cams are degreed in exactly to the manufacturer specs (107.5 intake and 108 degrees exhaust). The problem is, this motor has no bottom. Under a load, below 4000 RPM, anything more than about 1/4 throttle, she just stutters. I am going to advance the intake side about 2 degrees tomorrow. Just how many degrees do I need to advance the intake to actually show a difference?

http://www.thegsresources.com/_forum/showthread.php?t=140500

I think it is sorted now

Pos

[woodman]

Riding out west in Montana and Wyoming, premium isnt always available so I run at 10.25 - 1 in case I have to mix in half a tank of regular

[AOD]

Newer engines can run higher compression ratio because they have water-cooling...

[isleoman]

Modern bikes have variable ignition timing, knock sensors, fuel injection and other trickery to be able to run high compressions on pump gas. I personally wouldn't shoot for anything higher than 10:1 for an old school street bike. Drag bike would be a different issue with race gas or additives available.

I have 10:1 Yosh 1134 pistons, lightly decked head, and Dyna Ignition and it will ping on anything other than Sunoco 93.5. I try other premiums here in the North East and the Sunoco is the only one that consistently prevents pinging on my bike. I can drive around the pinging on lesser gas by not getting on it too hard, but what's the point in that.