yeas i used maths,,elementry,,,
once u understand what is compression ratio,, u can use any method be it analytical or mathematical to arrive at the resullts,,
get the equation for compression ration in single cylinder 4 stroke and understand its arguments u will b ok,,
i did both ways but analytic was easy as all i have to do is find volumes ,, mathematical equations involves volumes that cannot be easily compute as the surface of piston is not flat,,and u only know combustion chamber is spherical,,u dont know its equation,,
i would recomend u a small urdyu book that i had posted in soft copy edition in a thread search it and u will get the equation there,, or u can purchase it from the market at 50 rs ,, iis very nice handy book,, though very poorly written and wrong units are used but will give u a starting point to exploire further,,
back to ur question,, read about compression ration ,, amnd read my previous post ,, u will get ur results,,
if still u have problem just get results and i will help u in finding the final answer,,
also i donot have pressure gauge to measure pressure in psi 
squish volume wo hotha ha jo piston ka sides pa cylinder wall ka sath cylinder ki surface ka andar hi occupy hotha ha,, it also includes the gasket volume,,
i calculated it using clay,,(matti) ,but mix some used engine oil and very think shopper so the clay wont attach to the piston,, then put clay on that face,, then cut that clay extra part with thread,, then get that clay into a syringe it will give u volume in cc,,,
