Reply To: bottom cylinder fouling Big Twin 25hp

[The red boat]

thanks for all the replies.
I’ll try to answer best i can.
– the compression is the same as it was before
– the cylinders and pistons looked pretty clean when i changed the head – normal darkening but no carbon build-up
– i too thought about the plug wires and connections since it was becoming very difficult to start even before the head swap. That is what i am going to check next although my plug wires and boots were replaced 2 years ago. perhaps the bottom one is loose.
– I do believe the bottom cylinder has a weaker spark because when i pulled plug wires when it was running there was a significant difference between the 2 cylinders and how smooth they ran individually.
– no fuel pump on this one; just the pressurized tank
– i haven’t checked the oil drain system – will check that also. what is the fix for that? new assembly or just clean?

i have cleaned the new head and pistons; checked the rings to make sure they aren’t frozen; replaced a dirty inline plastic fuel filter;
now i am waiting for a new head gasket but in the meantime I will start with the plug wires and go from there.
the thing ran great all summer and only became hard starting in the last month or so – prior to the new head. so something has changed without me being the cause of the foul-up 🙂

thanks again