Well I just shuffled out to the garage, I have an old Jiffy 30, 8", the flute alone weighs 10lb 14oz. The motor alone is 24lb. Now I imagine some of the newer ones use a thinner gauge on the flutes, I'll just guess and say 8 - 9lbs or less maybe. Therefore I'm thinking you're probably pretty close with the 15lb estimate for the Honda powerhead. I know your issue with the back, I've got a couple of squashed disks, no fun at the best of times. Cheers.