Your link isn't working for me. I did find this string trimmer with the same item number as the one in your link.

http://www.lowes.com/lowes/lkn?actio...100&lpage=none

Thats a standard Ryobi 31cc engine. Much cheaper from Harbor Freight--but slow down--thats not enough HP for a 16-18 pound bipe.

You need a 40-50cc engine for an aerobatic biplane that weighs 16--18 pounds. I'd suggest a Poulan 46.

Here's a link to another trimmer with that same 31cc engine. Just for future reference if you ever want to build a bit lighter plane:
http://www.harborfreight.com/cpi/cta...emnumber=55008


Try this link and click on chainsaws on the left menu. There are 2 Poulan Pro chainsaws listed with 46cc engines. One is recondtioned for $140 and the new one is $220. I think some guys have even bought just the powerhead from lawnstation. Cheaper than buying the whole saw--which your going to throw away most of it anyway.
http://www.lawnstation.com/