The left engine was replaced 3 months ago...whole new shortblock and his friend who is awesome with them rebuilt it. He does a lot of work on them. He mentioned that he leaned the mixture out a little to make it more reliable but he said it is a little slower than stock because of it. The other engine was just rebuilt 8 months ago with new internals I think. They started right up with no problem at all. The left tach doesnt work...its stuck at 7 or something. The speedo spinner thing has a small peg broken off and thats it. Other than that it moves well. I did do a spin and the right engine stalled about 30 seconds after I did it. It restarted right away though when I hit the starter. He just told me that it stalled the engine because it sucked water back in to it??? How much better is the 2.5 merc then the rotax?