I have two of these engines. They have ball bearings and I believe they are non-Schunurle ported. They have an old air bleed design carburator and a one ring piston. My engines date to the early 80's.

The claim that the engines have the power of a bigger engine is probably just that, a claim. While it does seem to have plenty of power, the K&B 40 seemed to be about the same as the OS. My engines will turn a 10-6 Master Airscrew prop about 12,700 rpm. I have had some trouble getting a smooth transistion from idle to full speed. This could be due to the air bleed carb.

My LHS says that parts aren't available anymore. I find parts and parts engines on forums and eBay.