Well, I've followed these threads with interest.

I have a 91FX in a Hog Bipe... been a year now. Only one deadstick in all that time because I set it too lean. Otherwise a perfectly good engine, and she does pull that Hog vertical! Running a 13.5 x 8 Graupner.

I almost feel guilty with this fine engine, honestly... no problems! I think I've had the same glow plug since it was new.