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Thread: Opinions Please

  1. #1

    Join Date
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    Opinions Please

    Hey Guys,

    Bought this 98 GP1200 last year, didn't know much about it, other than it started, and I got a good deal on it. Ran it all last summer without much problem. So..........What I am interested in knowing, is what exactly do I have going on in the engine compartment ? I know it isn't stock, but I would like opinons on what I might have, without having to tear it down. Is it possible for the engine experts to give me an educated guess as to what exactly I have here, and what I should be doing to tune it for maximum performance/reliabilty ?

    The other mods I do know about are:

    - Pro-Tec intake grate
    - Riva ride plate
    - Sponsons (Unknown brand)
    - Pro-tec nozzle
    - polished stainless impeller (brand unknown)

    It runs really good down low, great hole shot, handles like it's on rails.
    Mid range has a slight/mild bog occasionally
    Top end, over 3/4 throttle has a babble with a power loss
    Max rpm in the 6700 range. at 3/4 throttle

    Any idea's as to what might be going on here? Opinions on what steps I should be taking to solve the stated issues ?

    Thanks Guys...........

    St4ngster
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  2. #2
    First check the compression and then go from there.

  3. #3
    bullisland's Avatar
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    You have aftermarket flame arrestors (the pink parts). Do you know the last time the carbs were rebuilt?

  4. #4
    Flying Scotsman's Avatar
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    Check comp if its good pull carbs and rebuild.
    Cant tell whats done from the pics.
    Stock is 120 psi rpm should be about 7000 and it should run about 60 mph on GPS.
    Carbs need looked at right away

  5. #5

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    Apr 2010
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    Eganville, Ontario, Canada
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    K, Thanks for the replies guys. On saturday I bought my wife a bone stock/mint condition 98 GP1200, and tried it out today. Well, I am more impressed with the performance of hers than mine. Pulls wicked hard straight thru the rpm range, and handles very well too.

    OK, so the cold compression is 100psi on all three cyls, and I'm not sure when the carbs were rebuilt, but I was just about to pull them anyways, so I will do that and post pics of what I find.

    Oh ya, I made a mistake in my original post, the top rpm is 6070 NOT 6700 and is reached at about 3/4 throttle, just before it starts to babble.

    Stay tuned.

  6. #6

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    UPDATE:

    K, pulled the carbs and checked out a few things:

    Low speed needle: (PTO - 3/4) (Mid -7/8 ) (MAG - 7/8 )

    Hi Speed Needle: (PTO - 1/2)(Mid - 1/2)(Mag - 1 1/2)

    Hi Speed Mag needle way off the others

    ALL jets were 100 pilots, and 135 Mains.............Hmm !

    All internal filters looked very clean

    All Needle arms were flush to carb body

    No visible signs of rips, tears or creases in any of the diaphragms

    Recommendations ?? Jets, needle settings, carb rebuild ?

  7. #7
    THe compression is low. Its even on all three so it could just be the gauge or a weak battery. But if it really is only pumping 100 PSI compression then that is why the stock ski is stronger. THat engine may be worn out.

    Try running the compression again charge the battery up good and let the ski warm up before doing the test and see if its any better.

    When you opened the carbs up how did they look inside? Clean or not?

  8. #8
    Flying Scotsman's Avatar
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    Can you tune carbs ?
    Those jets dont sound bad and it sounds like the carbs have been done already.
    Check the externall fuel filter
    If you realy have 100 psi you better pull the head and see why.
    Sounds like a hone and some new rings might be needed to get your comp up so you can get up to speed

    100 pilots and 130 mains might be better

  9. #9

    Join Date
    Apr 2010
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    Carbs looked really clean inside, no gunk, or corrosion. I'll check compression on the wifes ride and compare the two. Maybe the gauge is reading off. I'll also do a test on a warm engine as well.

    Can I just hone and do the rings ? I always thought that was a no-no, and the rings and pistons should be done as a set. Does the engine need to be pulled to do just this?

  10. #10

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    UPDATE:

    Just checked pop-off pressure. Each carb had a 1.5 N/S and a gold spring, which should equal a 55 lb pop-off. All three popped at about 48 psi.

    Well........they never really "popped" as I was expecting, but they started to release pressure, and hiss at about 48 psi.

    So, do these numbers seem about right ?

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