Re: Yamaha 115vs90
I'm pretty sure they don't interchange. I think the 115 and 130 will swap, but I think the 70 and 90 are different. I'm not sure of all of the differences, but probably drive shaft diameter and water pump differences. The best thing to do would be to look into a Yamaha parts diagram to compare part numbers between the 90 lower unit and the 115 lower unit. You might also contact Outboard Jets (the maker of the jet unit) to see if they might know. Chances are, they won't swap out. I have a 1989 Yamaha 115 with the jet, and I like it!
Ken