SX/SXi/SXi Pro 750 SXI-Pro Smashed Spark Plugs

[firemedicmonkey]

My first ski and my second problem...

1998 Kawasaki SXI-Pro:
Engine apears completly stock. Was told it was a lower hours boat. Came from salt water riding in Rhode Island....

When I got the ski it had two different spark plugs in it... 1 NGK BR8ES and 1 NGK BR8HS... I thought this was strange...

I looked up the factory reccomendation and got two new NGK BR8ES plugs and have put about 4-5 tanks through it. Besides the off idle bog that I am experiencing I have not noted anything out of the ordinary no weird sounds or anything. Although I have to admit I am not sure I would know what sounds right and what doesn't. I am a seadoo guy so i don't know but nothing catastophic sounding has occured...

When I went to check the plugs the other day I found that both of the plugs contacts where bent closer to the electrode... I have not checked the actual gap yet but I will try and get that done tonight or tomorrow and post pics...

What could cause this? Is it possible it has a milled head or something and that is why the PO used one shorter plug (BR8HS) He did not mention anything about that when I bought it from him...

 

[tor*p*do]

detonation will do that.
or loose chunks of metal in the cylinder
you are probably lean low which is the bog you experience
Kawi oem heads, shaved or not, should run the E plugs
pull the plugs in a dark garage, get a good light (fiber optic boresight is best)
and look at the top of the pistons
probably have no wash from being lean
may be able to see other damage if there is any

 

[firemedicmonkey]

What do you mean "wash" from being lean? I am thinking I will just pull the head and post pictures... That way I can get an accurate idea of what is going on inside the cylinder...

 

[tor*p*do]

 

[firemedicmonkey]

hmm I see... I never heard it called wash before... but know I know what I am looking for... Hopefully I will have it apart in the next few days and I can post pics...

 

[firemedicmonkey]

anyone got a working picture of this?

 

[tor*p*do]

I had one posted but the X gallery is still Fubared apparently

 

[jkirkland]

Am I seeing this correct? Center is perfect, all black is to lean, and the black only in the center is too rich? I would think that all black would be too rich, not too lean. Not that I know anything about piston wash. Just trying to learn. Thanks for any help --Jason--

 

[tor*p*do]

too lean is borderline detonation
BOOM! covers piston with carbon
there is no time to develop piston wash
the wash is where hot gasses are expanding
and washing the piston near the ports
too rich and carbon doesnt form
as unburned fuel keeps the piston clean through the combustion cycle
and you are dumping excess raw fuel overboard
usually fouling plugs in the process