Reply To: bottom cylinder fouling Big Twin 25hp

[The red boat]

The pistons didn’t need decarb when I swapped out the head. They were pretty clean with the normal amount of darkening. The top piston still looks like that.
The bottom plug was clean initially but after running like crap for about 5 minutes I pulled them. The bottom was completely black and somewhat dry and the top one was tan and just slightly damp (oil).
I pulled the new head back off because I thought maybe I screwed up the gasket or something since it wasn’t fouling plugs before. Gasket looked fine but tore when I removed the head – waiting for another one now.