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Kaveman: On the subject of compression ratios, here's the reason you see different #'s of 2 stroke and 4 stroke engines. The 11-1 for instance you see typically on a 4 stroke is derived from a mathematical equation considering bore, stroke, and combustion chamber volume at TDC. In a 2 stroke, this number is sometimes also used, but is not a real accurate measurement in a 2 stroke format. A 2 stroke might be 11-1 in that type of measurement, but part of the upstroke of the piston occurs with open transfer ports and exhaust ports that are uncovered, so that actual compression squish happening once the piston covers these ports might be more like 7.5-1. It is much easier to use the PSI figure which tells you real-life cylinder pressure at TDC. Clear as mud?

 

ShadyRascal, maybe you can help me out. At a elevation of 700-1300ft. what is the most compression i can run and use 93 or 94 octane gas with out running into detenation?

Oh i almost forgot i'm talking about the LT

 

My LT is at 170 psi, my home elevation is 3600, and I run premium pump gas, 91 octane here. Many would say I should run better gas, but it works. I think psi is a constant--170 at sea level will act like 170 at a mile high, it just takes a slightly different set up to achieve a given psi at different altitudes. My particular setup, 170 at 3600 ft, would be higher psi at sea level air. So, if you have 170 where you're at, I think you could get away with the gas you mentioned. Just my wild guess.

 

245 Holy Crap that must have been a little bumpy to kick start!