Damage Spark Plug #2

[dankchaa]

Hi everyone,

Yesterday after 1 hour smooth ride with my 2005 RXP, I noticed that the engine started to stutter for a second and after that it ride good for a while just before reaching at shore. I shut down the engine and let the engine cool off. After a while I tried to start the engine back, but it didn’t want to start again, only crank. Went home and removed the spark plugs. I noticed that the #2 spark plug was damaged (smashed) and that there wasn’t any compression nor suction on piston #2. The #1 and #3 spark plugs and compressions seem to be fine. Can someone tell me what happened with the engine before I take it apart so I know what to look for?

Thanks.

 

[greyrider]

sounds like a connecting rod let go on the upstroke allowing the piston to 'smash' the plug - with the plugs out do you hear any rattling if turned over by hand?
good luck

 

[dankchaa]

Thanks for your input Greyrider. No, it doesn't have any ratheling sound. Sinds you have mentioned that my guess is that the connecting rod could have come loose from the crankshaft and therefore not allowing the piston to go up or down to generate any suction or compression. I will do some measurement tommorrow to verify if the piston is moving while I'm cranking the engine.

 

[Dennis]

No compression

The defective cylinder probably has broken exhaust valve/valves. Supercharged engines had a problem with this.
DAWG

 

[Chester]

Just go ahead and take it apart. You won't have to "look" very hard to find the broken parts as it will be obvious what happened. Post your findings.

Chester

 

[dankchaa]

Thanks a lot, I will do that and keep you guys posted.

 

[dankchaa]

Hi, Finally got the time to open up the engine and to my surprise it wasn't pretty. Never thought that valves could break like this and damage the cilinder head. Did someone had this same senario?

Below are some pictures of the findings. pic#1 is cilinder head and pic#2 the pistons still in the motor block.
It seems like I will have to buy a new cilinder head. Let me know were to buy.

 

[Dr Honda]

Hi, and my condolences.

Anyway... I don't see too many people talking about it here... but with the new generation of high performance 4 stroke engines, valves breaking off is a very common thing. Ever since 4 stroke engines have started dominating the dirt bike world, it is very common to check valve clearances. We have found that the gap will start to close up well before damage occurs, and it is a good indicator of when things need rebuilt. (before catastrophic failure)

Anyway, there is a machine shop named Millennium who can weld up a head like that, and re machine the inside face. They will also install new valve seats, and valve guides. I'm not absolutely sure they do SeaDoo heads, but when they do dirt bike heads, they are a fraction of the cost of a new head.

I'll post a link to then shortly.

 

[Dr Honda]

Give them a call and see if they can re-work it.

http://www.mt-llc.com/Watercraft/watercraft.html

 

[JasonZE]

this is fairly common and the 04 models were the worst usually its due to rust on the valve stem from poor winterising but other times its just bad luck.
the head can be repaired but often the cylinder wall gets dented from the piston rocking over when it hits the valve and this often splits the cylinder at the top.

 

[dankchaa]

Thanks a lot guys.
It seems like I have to take care of my Seadoo like a Nascar car, After each run, take the engine apart and check for signs of wear and tear. Damm.