Lip in no 3 cylinder

[David Borg]

I took apart a 150 2.5 liter for a rebuild , bearings , crank and reeds are in very good shape .

I noticed that no 3 cylinder had scuffs and a lip at the top of the cylinder were the ring stops which can be felt by hand . also number 5 had some scuffing. the other cylinders look good some of which still have the crosshatch in the bore .

What would cause this ? overheating , Lack of fuel ( piston tops are black )

I will try and take some pics later on

thanks
David

[CAPTAIN CAMPER]

how many hours are on the motor i've seen motors with 300-400 hours wear the bore especally fishing motors

[David Borg]

engine has around 150 hours and it lost 4 mph on top , thats why I took it apart( after checking all electronics and fuel which tested out ok ) .

[Markus]

That's odd after only 150 hours. I have heard about the phenomenon in heavily loaded Yamahas with way over 1000 hours.

Has the boat been overpropped?

[David Borg]

It was spinning around 6400rpms ,

I thought maybe it had a local over heat, or maybe a worn wrist pin ( I still have to inspect that) ,

what I know is that he played a lot with the jack plate and he did nt have a water psi gauge might have overheated

What do you think ?

[CAPTAIN CAMPER]

anything is possible local overheat from low water pressure but usually you will see that in the temp check wrist pin and piston clearence

[Dave S]

Thing is to check for broken reeds. Small parts going thru.;)