I am flying a 57cc Stihl blower engine on a 35-pound stick and previously verified that a 25cc engine will almost not fly the same airplane at 28 1/2#. The few flights made with the 25cc engine were very, very marginal and dangerous. Someone built it out of plywood.

I am also looking for 60cc + conversions. The Stihl backpack blower was a good choice but is hard to find. I prefer magneto ignition but most saws seem to have a heavy flywheel magneto.

Stihl makes a surprising variety of engine sizes. There is no substitute for cubic inches however the numbers are in cc.

Weedeater
27.2cc

Brushcutters
25.4, 31.4, 30.8, 36.3, 40.2

Clearing Saws
30.8, 36.3, 40.2, 44.3, 48.7, 51.7, 56.5

Backpack Blowers
27.2, 44.9, 56.5, 64.8

There are more sizes.

Bill S