Thanks for having the time to help 3961,

http://www.americanpioneerhobbies.com/sukhoi120.html

This is the link of my plane

It's 70" wingspan, 60" long. made for 120-160 2stroke, 12lb.

I have an MVVS 26cc on it with a 16"prop. flew it last week but there was no power at all, it barely lifted and flew.

I have a smoke system fixed in it, total of three sets of batteries 1 for Rx, 1 for Ignetion, and 1 for smoke valve. i had them all along with the smoke valve ( Sullivan pump )
next to the tank( including the ignetion box) to, barely get the CG right!!! Really don't know why!

I'm thinking a 35cc would do, HOPING a 50cc will be ur answer since i've got one on the shelf.

any help here??? THANKS