ORIGINAL: Redback
I have had a 91FX in a TF Corsair for a couple of years now and it has always run fine. It replaced a ST75 which gave me nothing but trouble.
I just hope I haven't jinxed myself by mentioning this
Terry
I don't think you will but who knows. I have never used or worked on the OS.91 to say anything good or bad about them, it's just one of those sizes I don't see very often. I only have the SK .90s and think they are one of the best engines ever built, that and only a hundred beans a piece!!!