I know I sound like a broken record but check out the gas engines by NGH sold by Hobby King and Agape Racing and Hobby. They're basically OS engines on steroids, built much better, and much cheaper than the Saito gassers. I had 3 Saito gas FS's; the FG 20, FG 30, and 84 FSG. The FG 20 powered my 1/5th Stearman ok but I missed the snap my G-23 had and it must be run very rich. The FG 30 was the same thing and this little bugger seized up on me anyway. I purchased the three cylinder 84cc FSG3, ran it for 15 minutes at idle and it seized up on me. I sent it back, they fixed it, and I sold it. Trust me, you'll be much happier with an NGH engine. I have a 1/4 scale Camel and DR-1 with NGH 38cc FSG's on them and I couldn't be happier.