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  1. #1

    Trying to jet '98 GP800 for altitude

    Hi, I'm new to PWC and bought my first two last week. One of them is a í98 GP800. Itís a bit of a fixer upper but I was interested in it because I got a really good deal on it and it has a lot of after market goodies. So far, from what I can tell, it has a Pro Design cylinder head, twin pipes, and a Pro Tec intake grate. When I test rode it, the max RPMs were hitting around 8,000 so I am assuming it has an upgraded CDI as well. I canít see any markings on the ride plate so I am assuming it is stock. The previous owner didnít know what all had been done to the ski as the guy that put all the mods on it was two owners before him.
    The previous owner had someone go through the carbs last year and rebuild them. Afterwards it didnít run right and the guy I bought it from had no idea where to begin tuning it. When I took it for a ride, it didnít idle very well. When I gave it some throttle, it seemed to load up and really began to shake badly. After it sped up a few thousand RPMs, the vibration went away and it really took off.
    These watercraft carburetors are new to me. Iíve worked on my own snowmobiles for 10+ years and am excited to learn all about these carbs. I am hoping that someone on this forum might be able to give me a starting point for dialing them in. The previous owner rode the ski at an elevation of around 3,200 ft and I will be riding starting at 4,200 ft and later this summer up to 6,000 ft Iím looking for something that will get me close at the 4,200 ft elevation as far as the main jet, pilot jet, needle and seat, and spring. Is there anyone that can help?


  2. #2
    Bump. Is there anyone on this forum that rides at altitude?

  3. #3
    Mpeavler's Avatar
    Join Date
    Dec 2005
    Anderson, Indiana
    Your only going to adjust the top speed needles mabye...1/3 to 1/2 turn jetting changes will be required I bet. Don't tune anything unless you have a good tach to go by. You need a Pet 2100DX or Commerical grade Tiny tach that updates multiple times per second to truly tune a ski.


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