Hi CaptinJohn,

Careful... I looked into this a while back. Several sources said that I could use a 30cc piston/cylinder on a 25cc bottom end, but further research indicated I would probably encounter vibration problems due to an out of balance condition with the 25cc crank in the combination. To save any such grief, I bought a couple of 30cc Homelite blowers off e-bay, and used the complete engine. It's worth it though. My hopped up Homey 30cc turns an APC 16 x 8 prop at 9500 rpms on gasoline, and weighs about 2 ounces less than my Homey 25cc engines.

Good luck,
AV8TOR