I have an RCGF-50cc that I bought for $349. The thing runs outstanding, especially considering the low cost. Another one Ireally like is the Fuji BT-43ei. I hated it at first because the igniton was very noisy and caused a slot of radio/servo interference. After installing a CH ignition on it though it is just a sweet wngine. Starts super easy, runs smooth & reliable, and makes respectable power. Of course it costs almost $500.