Compression Ratios: What Ratio Would be Too Much?

[quexpress]

Hi!
As I was admiring the toys on this page:



http://www.pingelonline.com/wiseco_pistons.htm

I noticed that street compression ratios seem to run from 10.25: to 12:
The ones displaying 13.5:1 are all identified for Drag only.

How would a bike react on the street with these 13.5:1 compression ratios?
Just wondering ...

TIA!

[Dan Ruddock]

You need racing gas for 13.5:1
For pump premium 10.5:1 is all I would run. Dan

[cyclefvr2]

crotch rockets today are running 14:1 i believe, dont see the prob with 13 if the jetting n timing are right ,check into it,

[sk843143]

compression ratio dont make as much diff as cam timing does ..... with the proper cam size and timing i would think you could do 13 .... the power band would be real high though

[Dan Ruddock]

crotch rockets today are running 14:1 i believe, dont see the prob with 13 if the jetting n timing are right ,check into it,

No way is this true. Modern engines have highly developed combustion chambers, liquid cooling and computer control of timing, fuel mixture, knock sensors and even throttle opening to a level that a engineers would only dream about in the 70's and 80's. Running that kind of compression in a 70's machine would be criminal. Dan

[rapidray]

For an old AIR cooled GS, keep the compression ratio under 11.5 for pump gas. Whoever above posted new bikes are 14 to 1 failed to also post that those are WATER cooled & there is a HUGE difference in the heat in the combustion chambers between the 2! Stick to 10.5 to 1 you will be much happier unless, of course, you are building a high HP street race engine that will ONLY run on race gas! Ray.

[quexpress]

Stick to 10.5 to 1 you will be much happier

Thanks Ray!
What is the OEM ratio for the 16-valve GS1100?

[rapidray]

I believe it is around 9.6 to 1. Ray.