717 top end fail.

[matempl]

I pull the motor out of my gti and got the top end apart. This is what I found. The question is why? My motor had maybe 20 hours on it. I purchased it from a shop near Lodi ca. When I did the install I new nothing about sea-doos and I didn’t go through the carbs. However it ran great. Started having a dieing problem and I was thinking it was electrical issue. Now I think a carb leaned out. What’s the opinion here?

 

[mikidymac]

Well, being an unknown engine.... there are some variables but seeing the bad piston it sure looks like it ran lean. Typically it’s the carbs or fuel system.

Never replace any engine without doing the carbs.

 

[NickCawks]

Had to have been a poor tune.

The issue with running lean is your ski is going to feel amazing, but all the while that is happening on the inside.

I've seen many instances in this forum where people said something like "ran better then it had before" right before it died

I'm my personal experience (had a very similar failure at the start of Summer) it's always going to come down to the tune. It's not hard to get them tuned right, but it's much easier to have them tuned wrong

 

[chipskittles]

What has been said, carb went lean. If it's still got the grey tempo fuel lines those need to go before you run it again. And clean out the fuel selector.

 

[mikidymac]

You can’t clean the selector, just replace them for $25. Once the inside rubber goes that’s it.

 

[matempl]

Thanks for the input. Bottom end looks perfect. Sent the cylinders to full bore and sent pistons and plugs to get their opinion.
Looks like a lean condition to me also. Ordered carb kits and selector valve from osd today.
On another note,how do I tell if the carbon ring needs replacing?

 

[NickCawks]

well, the easiest way is going to be a visual inspection of the ring and impeller.

as for telling by its performance if the ring is bad you will experience cavitation which may cause the ski the bog down at low speeds and have a difficult time getting up on plane.

I have found that even on a carbon ring that is still in pretty good shape if you swap a new one in the ski can feel a lot better. Maybe worth your time and money if you're even thinking that its time to swap it.