# Yamaha F115 low power, smokes



## Homemadexj (Nov 3, 2011)

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.


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## AfterHours2 (Aug 2, 2010)

The reasoning behind the low compression is the first thing that needs to be addressed. Being the motor is a four stroke, you will likely have a high bill for a tear down, inspection and rebuild. I'm no outboard professional but I'm sure Cut or Creek runner will chime in as they work on Yamahas regularly. Good luck but the price quotes/estimates do not seem out of the ordinary unless the work is performed by yourself..


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## cutrunner (Jun 8, 2010)

I would have to do a leak down test.
That will tell you exactly whats wrong.
If its a stuck or bent valve it can be a somewhat cheao and easy fix.

Those 115's arent exactly sophisticated, pretty basic if you have a decent understanding of a fuel injected four stroke engine


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## Creek Runner (Sep 1, 2011)

> I would have to do a leak down test.
> That will tell you exactly whats wrong.
> If its a stuck or bent valve it can be a somewhat cheao and easy fix.
> 
> Those 115's arent exactly sophisticated, pretty basic if you have a decent understanding of a fuel injected four stroke engine


^This. Yamaha in recent years doesn't even recommend doing compression test on 4-strokes. Leak down test is all that should be performed on 4-strokes. 

Lots of things it could be need more diag. To find out the problem and get an est. of repair. 

Might just need a treatment of Mengenal Lebih Dalam Tentang


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