It takes some work, but I have gotten the Homelite 30cc engines down to around 2 lbs. 11 oz. when running CDI ignition. And if you hop them up, the power is pretty decent too. I have one that turns an APC 16 x 8 at 9400 rpms, and another, tamer one that turns a Zoar 17 x 8 at 8200 rpms. You can often find them in Homelite leaf blowers, and they are more common and cheaper than Echo engines.

The Homelite 33cc out of a Bandit Chainsaw is a pretty good engine too.

Those are the only ones I can think of that are cheap, reasonably plentiful, and make good power. I don't recommend the Weedeater/small Poulan engines as they are low on power and cheaply made in my opinion. From there you go up to the Stihls, Echos, etc., but the price goes up and the availablity used goes way down.

I probably have several engines that would work well for you, but I don't know how I would get them safely shipped to Mexico City if you bought one from me..... Do you have "Estafeta" delivery service there??

AV8TOR