Yes, you can hop up the older G-23. Dave's has big bore hop up kits for either the 2 or 4 bolt Zenoahs. If I remember right though, you can only get to 26 or 27cc unless you change the crank. But I didn't change the crank on mine, just added the big bore cylinder. But the 2 bolt cylinders are the older ones, and the 4 bolt ones are the newer style in my understanding. Keep in mind that the Zenoah tends to be a high rpm engine anyway, and the hop up cylinder makes it more so due to the port timing. The exhaust is around 172 degrees I believe I measured. It probably won't like anything larger than a 16 x 8 prop, and it will need premium gasoline due to the higher compression ratio, but it will scream!! I used a 12.7 mm carb on mine, and a nice free beathing muffler. It makes a very nice running, responsive and powerful engine.
I also recommend running 20:1 oil in one of these due to the high power and rpms involved.
AV8TOR
Last edited by av8tor1977; 05-12-2015 at 06:11 AM.