2159 piston carbon

[woodfarmer]

anybody know why my 2159 has a carbon buildup on the front half of the piston top, that would be right behind the exhaust port?

 

[motosierra]

Maybe you are running a fuel mixture that is to rich..

 

[HiOctane]

Probably caused the flow pattern from the transfers.The intake side is always "washed" by fresh gas and the shape of combustion bring the burned residue stuff at the exhaust side of your piston.Thats all normal.

 

[Urbicide]

There is a fuel additive called Sea Foam which works really well. I was referred to it by a Stihl dealer here who is a small engine guru (Don Dewar Jr). He recommended using a cap full to the fuel tank every time you gas up.

http://www.seafoamsales.com/motorTuneUpTechGasSmall.htm

 

[motosierra]

Probably caused the flow pattern from the transfers.The intake side is always "washed" by fresh gas and the shape of combustion bring the burned residue stuff at the exhaust side of your piston.Thats all normal.

That sounds like a good explanation to me...