YS140 it is five years old and this is the first time it has been run. I am using 20% oil Klotz, 15% nitro an OS F plug. The engine starts ok but keeps on surging or hunting. It did have the new style gasket installed, any ideas?? would be appreciated.
Thanks Ian

It sounds like the engine need to have the gas porting modification to the piston. It will have to come into our service dept to have this done.