Compression and Race Gas

[Kaw_Boy_5]

I am a little confused on what I hear about compression on various two strokes and the need for race gas. Stock 250's typically are in the 210 psi range and are fine on 92 pump gas. I hear that other bikes require race gas at much lower pressures (for example on a Banshee I hear that it is recommended above 160 psi). It seems to me that the need for race gas should come at the same compression reading no matter what size or brand of bike. Why is this different depending on the bike?

 

[SuzookKING]

bore size has to do with it along with the shapes of the head/piston.... the bigger the bore the more likely auto-ignition can occur. The flame front has to spread farther out and that takes a lil more time to do than on a small bore motor. This is in laymans terms, I am sure it will be enhanced upon by the experts shortly