Broke Piston....Why?

[jlw1972]

I am getting ready to put it back together now with all new pistons, bearings, etc. Everything but crank and rods. What could have caused this. Could this be a ethanol in gas situation. The other five cylinders are in great shape. Why only one? The motor is a 1995 Yamaha 200TXRT. I don't run high rpm's but have been using gas/ethanol mix. Just wondering what I could do to keep it from happening again? Rodbolt... Anybody else?

Thank's for any help, Joey

 

[rodbolt]

Re: Broke Piston....Why?

get a better shot of the #3 piston.

 

[jlw1972]

Re: Broke Piston....Why?

Is no. 3 the broke one or the one under it? Sorry for the lack of knowledge, This is a first for me. All I have is a Yamaha manual and my fingers crossed.

 

[jlw1972]

Re: Broke Piston....Why?

It's still blurry. Think i'm taking them to close. I'll be back in a few minutes with a good one.

 

[jlw1972]

Re: Broke Piston....Why?

Maybe this helps

 

[jlw1972]

Re: Broke Piston....Why?

Try this

 

[rodbolt]

Re: Broke Piston....Why?

looks like 1 and 3 got lean.
have the block inspected by a professional machine shop familiar with outboards, fix the fuel delivery problems and get back out there.

 

[timster]

Re: Broke Piston....Why?

Good info, One of my suzuki pistons broke on the edge just like that. I was wondering what would cause it as well. I guess i need to check my fuel system too.

 

[rodbolt]

Re: Broke Piston....Why?

that edge doesnt look broken,looks melted due to detonation.also looks like the fuel was old as well looking at the black deposits.