I found out what caused my piston to melt

[Reboot11133]

1984 Force 85Hp
Well my piston is on its way so I decided to start preparing for the re and re. I am going to go in thru the reed ports as suggested by Frank. Anyway I kind of screwed up and removed the bolts that hold the reed valves in place when taking off the intake manifold. When I pulled each reed valve out of the engine I noticed what looked like big chunks of sponge inside the reed for the cylinder with the melted piston on the carb side. The foam baisically plugged up over 1/2 of the reeds. There were also some smaller pieces in one of the other reed valves but fortunately no damage to the other cylinder. From what I can figure out the foam came from the acoustic liner that use to be covering the inside of the top cover for the motor. There is only traces of it that are remaining where the glue attached it. I have no idea if this was a factory thing or a previous owners bright idea to make the motor quieter.
My carburetors have no cover over the throttle body to prevent this type of thing from happening. Was there a cover origionally? There are bolt holes so it could be installed...Hmmm maybe ebay?

 

[jerryjerry05]

Re: I found out what caused my piston to melt

It came from the factory with a foam liner.It took a dump after about 8-10 years.The glue let go and it ended up in the flywheel and got chewed up and unfortunatly you got some in you carbs.DON"T put it back.Unless you want to have it come loose again. Jerry

 

[Frank Acampora]

Re: I found out what caused my piston to melt

And yes, the engine originally had a single airbox that covered all three carbs. It had the air intake on the starboard side, six screws held it to the carbs and three gaskets sealed it to the carb faces. There was a fitting on the bottom with a short hose connecting to a fitting on the bottom of the manifold. This recycled spit-back fuel and oil.

 

[Reboot11133]

Re: I found out what caused my piston to melt

I noticed that short hose after I removed the carbs and wondered where it came from...That would also explain the oil residue below the carbs. Is it common practice to remove a safety feature like that and throw it away? Does anyone know where I can buy a new or used air box?