Spark plugs

[UKGlenn]

Just wanted some thoughts. I have a 240m2 Efi second generation in Utopia 2004. Problem is I can put some new spark plugs in. The boat runs really well but then progressively gets harder to start when warm. If I change the plugs notice the gaps are shorter. Only thing I can think that would cause this is piston contact. Could this be possible and is it a sign they are about to give way?

 

[Tim75]

Sounds like the wrong plug or missing gasket. Badly worn rod bearings maybe.
Use only recommended NGK plugs.

Failing tps can cause hard to start warm.

 

[Tim75]

Sounds like the wrong plug or missing gasket. Badly worn rod bearings maybe.
Use only recommended NGK plugs.

Failing tps can cause hard to start warm.

In afterthought--
The plugs you took out- what was the gap when they were put in? OEM (NGK) gap is 1.0mm (.040 inch). When you say gap is less; can you quantify that?

Looking at the combustion chamber, it looks like a piston would hit the cylinder head before it hit the spark plug electrode. (ebay- search "seadoo mercury head".)