Dave, I looked at changing port timing as Keith at BME suggested in another thread. But decided against it as I have plenty of power for the plane. I could turn more RPM's but the plane will not fly right which is big and slow. I rebuilt the engine as in all bearings, gaskets, and seals. Just got the new rings for it finally, and will pull it apart to change them. May get a little more compression now which will be good. These engines are a lot of enjoyment to build. Just got my short blocks for the 44 and 50 CC Echos. Also will try and tear down the 3 26cc engines this weekend. Will let you know what I end up with. May take all 3 to make one real good one.