RE: OS 70 Surpass Ultimate
My Os fs .70 ultimate engine with the blue head works a dream. I bought it at Christmas and i put on my Black horse chipmunk. I had a bit of running problems to start off but i took it upto my local club and the club trainer had a bit of knowledge on 4 strokes. He had to completely re tune it after the 3 tank running in period the engine still is running with 6 tanks having run through. My engine has loads of power and is running better than any 4 stroke i've ever had. My Chipmunk is super aerobatic and can do loads of 3D and aerobatic tricks i can do super fast barrel rolls and it flies straight. I think this engine is great and you just need to get someone with experience.