Rebuild Or Sell 2008 90 2-Stroke Yamaha

[westbaykenny]

I new here and first want to say hi to everyone. It looks like a valuable reference tool.
My mechanic said I had a head gasket leak and it caused it to score the no. 3 cylinder. It has good compression on al three cylinders, but he also said there's play in the piston.....SO machine shop for honing and new piston or sell and replace? I've heard around $1500. for fixing, but if I sell it what's it worth?

 

[99yam40]

it is only worth what someone wants to pay for a broke motor or sell the good parts separately

by the way I do not understand how a head gasket would score a cylinder

 

[tommarvin]

Smells like fraud.
Good compression on all three cylinders?
Head gasket leak scored # 3 cylinder.
Go get your boat, remove the head and look for yourself, If it's ok torque down a new head gasket call it good.
If not you may need a bore and hone, should be less than $1500.00 if you do it yourself.

 

[flyingscott]

A head gasket can cause scoring if it leaks water into the cylinder. Take the head off and look for yourself hard to say if it's fraud or not since we are not there.

 

[westbaykenny]

I trust these folks and saw the pictures. They could have fixed other things but stopped after seeing the cylinder & piston. And yes the gasket wasn't torqued properly (my fault) and water hit the piston leaving a shiny ring around the top, and eventually scoring the cylinder. He said it could last 6 months or it could last one more trip.
Thanks for the replies.

 

[flyingscott]

I would fix it, they are good motors and at least if you get it fixed you know what you have

 

[99yam40]

maybe someone can explain how water in the cylinder from leaking head gasket could score the cylinder and piston/

Too much water can damage rods and piston due to not being able to compress liquid.

but small amounts of water will not score the cylinder and piston.

over heat will melt aluminum pistons, usually along the exhaust port side of cylinder

lack of cooling or lean fuel to air mix causes pistons to get too hot and melt

 

[flyingscott]

maybe someone can explain how water in the cylinder from leaking head gasket could score the cylinder and piston/

Too much water can damage rods and piston due to not being able to compress liquid.

but small amounts of water will not score the cylinder and piston.

over heat will melt aluminum pistons, usually along the exhaust port side of cylinder

lack of cooling or lean fuel to air mix causes pistons to get too hot and melt

Oil floats on water. So when you have enough water in the combustion area it prevents the oil from coating the surface causing a lack of lubrication. It absolutely can happen my guess would be it's been going on for a while it's a cumulative effect. Your first point about compression would have to have happend while the motor was running and got submerged. Water is a coolant not a lubricant they spend a lot of engineering dollars to keep water out of the combustion area must be a reason for that.

I guess I would need someone to explain the benefits of water in the combustion area.

 

[99yam40]

there are some that inject water into motors to increase power, but it has to be very regulated or it will not let the fuel burn properly.
they used to dribble water or transmission fluid into carbs or running old warmed up automobile motors to break up carbon..
have read about bad carbon or crusty oil build up on plugs on some 2 stroke OBs that had water interring the combustion chambers, but not scoring of cylinders.

I guess it would depend on how much and what kind of water maybe

have read about backing down outboard rigged boats that had water come up the exhaust and destroy motors