| You have a choice. My one is supposedly 17:1. I think standard they come at 15:1. I say supposedly because true compression ratio in a 2 stroke is not as easy to measure due to the ports. Generally, they are never accurate. In the outboard world we tend to go by Psi generated, measured with a compression tester. Sorry about the over information, but I can't halp it. :wink: | 
