I have 2 Troy Bilt 21 inch push mowers that I'm thinking of replacing the engines on. They came with 140cc Briggs. Question is this... Would you go with 163cc Briggs or Predator Brand 173cc? The 140 Briggs is not very reliable after a season of 25 or so weekly mowings. I have 2 Troy Bilt push mowers that are 4 years old and still going strong one Troy Bilt brand engine and other 163cc Briggs. I know... I know it's not commercial but I have NO choice financially right now. Thanks