I know this isn't a microskiff engine but need some advice on what to do with it. A friend of mine has an 05 yamaha 115 4 stroke that has low power and smokes a little bit. I did a compression check and the 2 middle cylinders are at around 80 psi and the 2 outside cylinders were good at about 140psi. We are trying to decide on having it rebuild. Kinda wandering what else I can do to find out what the problem is without taking it apart. Could it be a head issue or is it most likely rings? I'm hoping one of you marine mech's can help me out Got a couple of quotes if it does need a full rebuild. Performance outboard and machine said $6500 for a complete rebuild with all new parts. I wouldn't think it wuld need all new parts though. Also called Jasper and was quoted $5400 for a powerhead with 1 year warranty and $1100 for a cylinder head alone. At $6000+ he would rather buy a new one.