View Full Version : Yamaha 115 compression issue

08-26-2009, 07:55 PM
"Hi I have a yamaha V4 115 HP that has 4 cyclenders, 3 of which appear to be tight with @140lbs of pressure in them and one that won't get past 30lbs. the head was removed and we found pitting on the head and piston and we where told that it sounded like it was grinding a bucket of bolts by the previeous owner.http://www.marineengine.com/discus/messages/12481/292293.jpgPiston and head damage"">http://www.marineengine.com/discus/messages/12481/292294.jpghead damage""> these pictures show the damage caused by something bouncing around in the head but we never found any debris and the starter moves all the works just fine.
what else might be the cause of this damage and loss of pressure in the cylender and is it hard to get to the rings for just one piston?
thanks in advance to those who answer.

08-26-2009, 08:08 PM
wow that looks ugly.
Actually a sickening feeling comes with it.
No envy here!
Parts of a broken spark plug?
Something sucked in thru the intake port?
I truly hope you get it fixed without remortgaging the house.

08-26-2009, 11:13 PM
"yea that cracks me up as the price to fix was quoted at 2700. I assumed it was damage from a spark plug tip as well but I got the motor after several hands had already been on it.
not too sickning for me really as I don't have much fear of digging into them I just never had to dig into one of these. I ride a hog and have had it apart in the living room and my truck ( ford 350) has been ripped into here and there, so this is just another motor in my life. I just wonderd if I could get a little insight before I tackled it out right.
I think I might have ring damage as the compression is way too low and oil in the cylender didn't do it much good. we even hoped it was a head gasket but I say rings and that's why I'm here.
we have controls coming in the next day or two and I might throw it back together to see if WE hear any nutz and boltz in the works. or not. thinking of just digging out the piston and replacing the rings.

08-27-2009, 06:59 AM
"looks to me like you broke a ring in the cylinder. that is quite a joke $2700 to fix. you can finda a replacement motor for that price, at the very least a short block you could transfer to your engine."