I’ve been flying the O.S. 55 HZ for a little bit now. This engine is indeed a vast improvement over the previous O.S. 50 Hyper. It is a complete redesign from the ground up. Inspired by the well known and reliable O.S. 91 HZ, the new 55 has a 3 needle carb allowing for better tuning. Engine internals are quite better too with a better piston/sleeve design and of course a little bit more capacity!
Not sure about estimated retail price at this time. The engine is now available in some Asian markets, we expect general release in the US around mid October.
I am currently running this engine with the new Hatori SAB-56 muffler as it was designed for it. However, the Align muffler works very well with it too. Also, O.S. is planing on releasing a muffler specially designed for it too!
