RE: Is a Poulan 25cc a weaker engine?
Better off with a higher quality engine. I do a lot of yard equipment repair, and those Weedeater brands are the cheapest made out there. They usually aren't worth repairing and I throw them in the trash. They are also low on power once converted for airplane use, unless you get into a lot of porting.
Sorry for the bad news....
AV8TOR