Informações erradas no manual furam pistão!!!

[regis_patty]

http://www.sea-doo.net/SHOPMANUALS/JETBOATS/1998-1999/JBOAT_A/1998/LMR98V1A.PDF

Esta vela de ignição não serve para o motor rotax 800!!! É um absurdo estar no manual!!!!

 

[Coastiejoe]

If possible, use English as MOST do here at the site.

Here is a translation via Google, This spark plug does not fit the engine rotax 800 !!! It is absurd to be in manual !!!!

If the engine has been rebuilt there are factors that can play into spark plug issues. Has it been rebuilt?

 

[Coastiejoe]

As the bottom of the plug is not destroyed, I would start looking at your engine being "Lean" and or your timing is off. With a lean condition, the ignotion will eat a hole right through the piston..

 

[Dr Honda]

As the bottom of the plug is not destroyed, I would start looking at your engine being "Lean" and or your timing is off. With a lean condition, the ignotion will eat a hole right through the piston..

Yep.... I was heading the same way.

That's pre-ignition eating the piston. AND... what's the plug in your hand?

 

[regis_patty]

First thank you for your attention !
This engine was replaced the same piston melted , but was working perfectly until I replace the candles and read the manual that posted the link to you the spark plug shown for my boat , I made the exchange and the result is in the pictures.
I will check the ignition timing as pre ignition seems a possibility, the main issue is to contact some mechanical I was told they have seen several cases where this candle cause hole in the piston to be according to them warmer and longer .

 

[Coastiejoe]

The oil system on a 2-stroke is critical. It is part of the combustion. As such, if there is an issue with the oil system the engine will run lean. If it is lean, it will eat a hole right through the piston. You will want to look at anything to do with the oil. Lines, connections, and adjustment setting.

 

[regis_patty]

I had already thought of isolating autolub and mix the oil into gasoline

 

[regis_patty]

just keep autolub to lower lubrication

 

[ialonso]

Also poor fuel flow may cause the engine to run lean. Make sure your carb is clean and running at factory needle and settings, or richer, but not leaner.

 

[racerxxx]

First thank you for your attention !
This engine was replaced the same piston melted , but was working perfectly until I replace the candles and read the manual that posted the link to you the spark plug shown for my boat , I made the exchange and the result is in the pictures.
I will check the ignition timing as pre ignition seems a possibility, the main issue is to contact some mechanical I was told they have seen several cases where this candle cause hole in the piston to be according to them warmer and longer .

What is the exact part# on the side of the spark plug? Can you post a pic? Did you buy a BP5ES spark plug, like what is shown in the manual that you posted? If so, that is NOT the correct spark plug, that is just an example of a break down of what spark plugs are available, not necessarily the correct one for your boat. So your boat should have a BR8ES spark plug. If you did put that spark plug in there it more than likely is what melted down that piston. There might (If I recall correctly) be a white label on the inside of the part of the boat that holds the storage tray above the engines. That would list the correct spark plug and gap and a few other specs. I know it's on my 99 Speedster, not sure about the 98 Challenger