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  1. #1

    Need Help ASAP with elevation and XP 787

    So I got a deal on a 1997 XP with the 787 motor in it for 1500 with a trailer. The owner said it used to run the typical 55ish when he had it in Illinois but now here in Colorado with lake elevations of around 5000 its running in the 35-40 range only because it needs the carbs to be tuned… Does this sound correct? How easy will it be to tune? And what top end can I expect out of it? If its not great I’m thinking ditching this deal and waiting for an XPL… Thoughts?


  2. #2
    wotxxxsd's Avatar
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    Start by rebuilding the Carbs.
    This shit fuel we have now ruins Carbs in 1 season.
    There could be a wear ring issue.
    Prop issue
    I know the elevation does factor in but not losing 20 mph.
    Also I don't think he was running 55mph on gps.
    Maybe it showed 55 on the dream o meter on the dash.
    There are multiple things to check but rebuilding the Carbs is Def 1 of the places to start.

  3. #3
    From one high elevation rider to another, the biggest difference you will make is an impeller. All the jetting in the world will not account for the lost power at higher elevations. The XP was not a powerhouse. My xp limited stock will do 54 on GPS at 5k ft elevation in slight chop.

  4. #4

    Join Date
    Jul 2010
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    i would partially disagree with wire 4 money. I have ridden snowmobiles in Missouri and taken them to Colarado and the same for jetskis. I always rejetted them and reclutched. At 8-10000 fit i experienced 30% loss of power and a Denver are your loss of power should be 10-15% power loss and you need to rejet. Put in a fresh set of plugs go and ride your ski, look at the plugs after riding for 10-15 minutes in mid range power if there black your to rich, next step ride your ski full throttle near the shore for about 100 yds and hit the kill switch without letting off the throttle. check plugs again. If they look black they are to rich= you need smaller main jets. Very IMPORTANT if your plugs are white stop riding the ski and a richen the main jet like 75-85, lean to rich. You must relize that you have less air at altutude that at sea level it effects motors and performance. just like a riding at 100 degrees vs riding at 70 degrees more power at 70 degrees

    your xp should run about 38 mph at grand lake colorado at 8500 ft because i know first hand i have ridden that ski on shadow mountain lake, so in Denver it should run in the low 40's.

    If you want more speed you can compensate for a aftermarket impellar

  5. #5
    Quote Originally Posted by snoproken View Post
    i would partially disagree with wire 4 money. I have ridden snowmobiles in Missouri and taken them to Colarado and the same for jetskis. I always rejetted them and reclutched. At 8-10000 fit i experienced 30% loss of power and a Denver are your loss of power should be 10-15% power loss and you need to rejet. Put in a fresh set of plugs go and ride your ski, look at the plugs after riding for 10-15 minutes in mid range power if there black your to rich, next step ride your ski full throttle near the shore for about 100 yds and hit the kill switch without letting off the throttle. check plugs again. If they look black they are to rich= you need smaller main jets. Very IMPORTANT if your plugs are white stop riding the ski and a richen the main jet like 75-85, lean to rich. You must relize that you have less air at altutude that at sea level it effects motors and performance. just like a riding at 100 degrees vs riding at 70 degrees more power at 70 degrees

    your xp should run about 38 mph at grand lake colorado at 8500 ft because i know first hand i have ridden that ski on shadow mountain lake, so in Denver it should run in the low 40's.

    If you want more speed you can compensate for a aftermarket impellar
    impeller is very important to get the rpm's up. These pumper carbs in watercraft will actually pump less fuel at a higher altitude. You really need to get way up in elevation before you need to rejet. When setting up my watercraft for my elevation (5000') impeller was BY FAR the biggest change. The engine ran the rpm's it was supposed to. With stock jetting, I never fouled plugs. Snowmobiles are very different, and you also need to set up the clutching for elevation changes to get the r's back up. The OP wants to set up a 787 for 5000' riding. Been there, done that - repitch the impeller, get a high compression head and go from there.

  6. #6
    Read this:

    http://www.pwctoday.com/showthread.php?t=340963

    Bill is probably the most knowledgeable seadoo person alive. He used to run the factory race team back when the 787 was new. His shop has helped me set up my boats for use at high altitude, and the impeller and head are the two most important things.

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