Between a friend and I we have 2 each of the OS 91 FX engines. All have ran perfectly from day one.

That is 4 of these without any problems whatsoever. These have been purchased as long ago as 4 years ago and the latest last month.

Neither me nor my friend has had any problems at all with any of these engines.

I sure havent seen any problems at all with these engines. In my book they are fantastic!!!!!!!!!!!!!!

Between the 2 of us we have had 5 OS 46 FX engines, 2 OS 50SX engines, 4 OS 91 FX engines, 1 OS 46 SF engine and 2 OS 160 FX engines and all have performed perfectly out of the box. In my book I won't purchase anything but OS!! Except for a few Moki's and YS engines they are fantastic also.

Just my 2 cents.