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View Full Version : "actual" compression ratio of newer gsxr,s



MattTLS
Fri Feb 28th, 2003, 01:04 PM
Has anyone measured the compression ratio of the new bikes? The 750 and 1000 claim CR of 12.0:1, and the 600 goes to 12.2:1.

As with a lot of the numbers manufacturers like to give, the CR isn't always completely accurate. For instance, the measured CR of my TLS is closer to 10:1 than its claimed 11.3:1.

Just curious...

Matthew

rocktboy
Mon Mar 10th, 2003, 11:35 AM
what is your method for "measuring" CR?
isn't the CR simply calculated from the bore/stroke?

MattTLS
Tue Mar 11th, 2003, 02:13 PM
With the piston at top dead center after the compression stroke, measure the volume of a light oil it takes to fill the combustion chamber to the seating surface of the spark plug making sure there's no air trapped in the chamber. Subtract the volume that would be taken by the spark plug if it was installed. Add this volume(clearance volume) to that of the cylinder displacement (pi * (bore/2)^2 * stroke) and then divide that by the clearance volume.

It's probably easier to follow as described by Kevin Cameron in "Appendix B" of his 'Sportbike Performance Handbook'.

Matthew