Rich... or Lean? (Videos Inside)

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garrettb

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I had my GTX out on the river this weekend, and finally finished break-in of my new SES engine. Overall, it ran awesome. I finally had the courage to hold wide open for a few seconds and hit 60!

I still have a few bugs to work out with the carbs though. My question to you experienced tuners is, am I running rich, or lean? After messing with the low speed screws, and checking the plugs, I came to the realization that I have no idea what I am looking for. The manual is pretty useless in the sense that it just says, "adjust the screws until smooth engine operation is achieved." The problem is, the engine sounds the same with any setting I try!

*The following videos and picture are with the low speed screws at 1.25 from seated (2000 GTX 951)*

The first video is the bog I get when hammering it from idle. As you can see, the second try always results in a good power up.

https://youtu.be/2_48KwrqO_M

This video shows the weird bog/hesitation I get when accelerating very slowly. It happens around 3k, right before I get up on plane. If I accelerate faster, the stumble doesn't happen. More throttle or less throttle always "fixes" that issue I attribute to poor carb adjustment.

https://youtu.be/KZPBLCMBD2w

Here is one of the plugs after idling for a minute:

IMG_1861.jpg

So.... rich or lean?!
 
Your pop off pressure should be between 19 to 23 PSI
Your low jets should be set to 1.5 and high jet to 0
This is the specs for your ski however low jet could be adjust +/- .25 turn depending on where you live.
 
You did rebuild the carbs correct? Did you verify that the a pumps are working? Set carb settings to the stock settings if the carbs and fuel system are in order it should run just fine
 
It's a little hard to tell, but the spark plug looks about right to me, you need a little more time on the spark plug. There's a diagram and explanation in this article.
http://www.seadooforum.com/showthread.php?4151-Snipes-Korner

Like 1of500 said, if the carbs. were overhauled correctly, using mukini parts, pop-off set correctly, the ski should run fine at the factory settings.

Lou
 
What a great article. Lots of good information there.

I just cleaned the carbs, I never rebuilt them. I pressure/leak tested everything per the manual, and found no issues with the two carbs or the accelerator pump. To be honest they were so clean I probably didn't need to spend time with the carb cleaner, but I did anyway. I'll reset the screws to 1.5 and just be done with it. The misleading thing is the factory seat/spring combo gives a pop off of 25 PSI, while the Seadoo manual calls for 19-23 I believe. Based on that, my pop off is technically "too high" but 25 is exactly what Mikuni says it will be with the stock setup.
 
First I would buy oem rebuild kits and change everything but the springs and arm. To the untrained eye you might be missing something. Remove your H and L needles as well as your jets, clean them well. Make or buy a pop off tester and check your #'s. You can always tweek your pop off by bending the arm a bit. Spray carb cleaner into the acc pump lines going to the carb, you should see a solid stream spraying inside the carb body.
 
I bought a Mityvac to pressure test everything. Carb kits are expensive, and everything tested perfectly, so I don't see the sense in replacing what isn't broken. Everything was disassembled to clean. I set the arm height to be flush with the body, like the manual states. My pop off is 25, because of the seat/spring combo. Check valves for the acc. pump work great.
 
So your saying you think the internals are good on the carb from a ski from 2000 ? 16 years later ( if they were never rebuilt in any of those years ). The only thing the tester will test is pop off and if you have a air leak. Did you visually see carb cleaner or gas squirting from the acc pump nozzles in each carb?
 
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