Hi QSR, welcome to Outdoorking. Thanks for posting that report. Despite its smaller capacity and power than the Honda GX120, your Kawasaki FJ100 should be at least as powerful as the original engine fitted to your mower (and considerably more powerful than Deejay's G100, which he is very happy with). Does your Kawasaki have a 3/4" output shaft, or 5/8"? Scott Bonnar supplies engine side clutch-halves of both sizes, but it would be useful to our members to know which size the Kawasaki requires.
I would not personally want to have either a height-raising adaptor plate, or a need to dismantle part of the engine any time I had to remove it from the mower, but this is a matter of personal preference. If the engine is smooth and quiet, as well as having Kawasaki quality and durability, it is certainly a valid choice. At only 100 cc, it probably uses even less fuel than a GX120.
