Re: 50cc vs 80cc
There are lots of ways to cheat when you think about it. On a 4 stroke it would seem that you would measure the full stroke but when you consider valve timing overlap you are not getting a full stroke of compression out of it, especially on race cars. On a two stroke your compression stroke does not really begin until the rings cover the ports but for marketing I am sure the full stoke is counted there as well. My mic set is has been history for decades so I have not indulged my couriosity on how many cc's of true compression I am getting out of my 50cc, and there are so many other factors involved anyway it is not that important to me.