"BUMP an old thread"
Finally got the F-50R... was a Christmas present from my wife... Hornet Flyer, sorry you had a bad experience... its imperative you per-lubricate the bottom end and valve train when starting up a new 4 stroke engine... the "R" out performs my OS GF40 as expected, producing just over 4.2 HP with a Xoar 20-10... I've got mine in a H9 super cub, I have about 20 flights on it, and very pleased with the performance.
This is the video that got me interested.
John M,