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  1. #1

    Join Date
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    Help on tuning modified 1200r please!

    Hey Gang,

    I broke a major rule by incorporating too many mods at one time, and now I can't get the ski synchronized well enough to run better than it did without the mods!

    Any thoughts or help are welcome. Here's what we've got:

    '02 GP1200r with...
    block-off kit
    wave-eater clips/couplers
    IR Holeshot kit
    Carb rebuild from IR with
    hi/low T-handles, primer, choke plate removal, etc.
    K&N flame arrestors
    Pump seal kit
    Tunnel reinforcement
    14/20 prop balanced/trued/finished by IR
    Free flow exhaust
    D-Plate
    Riva Ride Plate
    R&d intake grate
    Speedwork heads and domes with girdled head kit
    Compression ~170 run on 100LL

    Initially it ran OK at WOT then shut down from a presumed overheat code; Right after restart it was limited to 4k RPM.

    Reset CDI, retorqued head bolts, and ran the ski to test carb settings but low/high ends were way off with RPM's seeming to be limited at around 5200 RPM (have not installed Tiny Tach -commerical, yet. Sorry!)

    Checked plugs with #3 good, and #1 and #2 looking rich, so they were dialed back 1/8 on the lo handles. Running the ski thereafter showed NO low end. The ski just burbles at partial throttle (seems indefinite) and dies at WOT from start. If you have the patience to wait for it to get going, the top end maxes at 52 mph with rpm at ~5200.

    At start the ski seems to have a stutter at idle and seems to require mega-enrichment to turn over (6+ primer pumps).

    Compression check is pending this weekend.

    How do you tell if a cylinder is not firing?
    Is plug reading reliable for checking low/high carb adjustments?
    Where should I start with this thing?!?

    If no one can help, I'm open to offers on a ski with mean potential and 47 hours! (I'd rather have the help, though.)

    Thanks!


  2. #2
    Moderator OsideBill's Avatar
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    I want to see the results of the compression test. Carbs usually go bad over time not bang like that, so I would not look too hard there yet. the heat thing has me concerned. did you dial in your jetworks?

  3. #3

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    I was under the distinct impression that the jetworks was "plug and play" from the IR paperwork. I know there are different kinds with adjustable pressure pop-offs, but I've done nothing to this one.

  4. #4
    Moderator OsideBill's Avatar
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    Post some pics of your jetworks mod too.

  5. #5
    BoostCrzy's Avatar
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    and do you mean 100LL as in AVGAS?....

  6. #6
    Moderator beerdart's Avatar
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    100LL not good..

    100LL (Blue) avgas
    Contrary to popular belief this isn't 100-octane fuel. Aviation fuels are rated on an ASTM Lean/Rich performance number system. 100LL is rated at 91/96 By comparison; Unocal Leaded race gas that is used in lots of spec fuel racing classes has performance number of 112/160. 100LL is closer to 91 octane (MON); by comparison VP C12 is rated at 108 (MON).

  7. #7

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    Sorry for the confusion on the gas, gang...

    The gas is 50/50 mix of 93 pump + 107 leaded race fuel for a theoretic octane of 100 with lead. I do think I let some flying background go from subconscious to post. Sorry!

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