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  1. #1
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    ???? What am I missing on this set up

    OTO19231...2000 EFI With 4 hole intake and a set of Boysen 250 XB Reeds, cut Heads at 63cc they were 250 EFI heads he cut... Motor runs real strong with stock 225 boxes... got another set of boxes reflash by Eric Simon. 300ING/250xb fuel... motor launches out of hole great but hits a wall around 5200 and falls flat and starts to surge... so I eased back to landing. Put stock boxes back on and runs super... Right up to 5900 and pulls real strong... figured it must be in the boxes... So I order a brand new set of 250XB boxes.. guess what does exactly the same thing... runs up strong to 4800 and starts the surging again... hits a wall at 5200rpms... What is missing with this application... Need some imput please... runs perfect with stock boxes

  2. #2
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    Timing or fuel

    timing to advanced will limit rpm, and fuel you know.

    Just not enough to knock

    read the plugs or piston and check the advance curve.

  3. #3
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    What makes no sense is the stock 225 boxes Run perfect right up to the limit where it will beep around 6000 rpms....This is on a Champion 20' Bass boat that weighs 1800lbs ...boat runs 72 on GPS turning 5900 rpms with a 26.5 Tempest.....I'm just looking to tweak it a tad to get a little more out of it....From what I was told just put new boxes on it and it will come alive being the Head work was done with the new reeds....I was also told to leave the Tuner in because the 2000 model was not restricted much at all....Crazy

  4. #4
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    The mota is gonna tell u what It wants , do a plug chop with stock ecu and if all is gud , have Simon match it with little mods , to much fuel bogging down? Just pulling straws , I'm a carb guy

  5. #5
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    Have you checked fuel pressure under load?
    Daddy taught me to never force anything but to just get a bigger hammer.


    1995 19'0" Champion bass boat
    1995 200 XRI

  6. #6
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    I agree more likely starving out on the 250 fuel curve on the stock injection fant remember if 250 and 2000 are different size. The 225 box probably doesn’t let it starve as much and make rpm.

    This is is if the injection is different size.

    To rich will also bog it down your after 11:1-10.2:1 at 12:1 or 9:1 you lose rpm.

    Could also blame stock stock pumps and regulator issues that show more problems with the 250 and custom box.

  7. #7
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    Same fuel pump for a 200 to 250, but it could still be a weak pump, ran into to this on my stock 200 xri efi it was surging and wound up putting it on dyno and cranked it up to 5500 rpm and fuel pressure was dropping out down to 20 pounds and bouncing back and forth replaced pump and alls good.
    Daddy taught me to never force anything but to just get a bigger hammer.


    1995 19'0" Champion bass boat
    1995 200 XRI

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