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  1. #1

    Blaster1200 question. underpropped or running lean on the top?

    So I installed a beat ass old GP1200 motor with good compression into a WB1. Today I took it for it's first lake test and it did good but has a LOT to offer!

    First off...my stock 98gp1200 pulls like a train from idle to WOT.

    The blaster is setup as follows:
    - 100 lows
    - 135 highs
    - 1.2 N/S set at 63 psi pop off
    - 1.5 low out
    - 3.0 high out(needed lots of fuel..more on that)-
    - 120ish compression across the board
    - Ocean pro flame arrestors
    - Solas 14/21 as recommended by Impros

    So I can't just grab WOT. It will bog. If I easy out of the hole...it will accept 75% throttle.

    Anymore than that and it looses speed and sounds like it's hitting a limiter. When I started on the lake today with 1.0 out on the highs...plugs were WHITE. Pulling the highs out got me a nice tan color but I'm still wondering about the WOT.

    My question is...should I get a little more prop or go up on the mains?

    Thanks

    JasonClick image for larger version. 

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    Last edited by vdubspeed; 06-28-2015 at 05:32 PM.


  2. #2
    quadzilla's Avatar
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    My question is...should I get a little more prop or go up on the mains?

    Thanks

    JasonClick image for larger version. 

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    Hey there Jason...

    I would very much doubt you need to go up on the mains..

    If anything you need to go up on the prop a LOT.!!

    On the 144mm pump you will likely need to be around a 16~23 pitch..

    If you are still on the 144 pump you will be HARD into the limiter almost immediately..

    Have any mods been done to the motor.?

  3. #3
    Yes sir...still on the 144. Seems to work for most people. the 155 is too much work and I just put a Blowsion metal 144 pump shoe in and won't be doing that again anytime soon! LOL.

    I was thinking the SAME thing. I was thinking 15/22 but might just make the jump to 16/23.

    The motor is BONE stock. Unknown history. Tested the compression again tonight at 121-122 across all three cylinders. Starts AWESOME hot or cold. Pulls like a freight train from 5-75% It's seriously a riot. Can spin around, sink down and then launch itself out of the water. Water skips real good to. John Boat wakes are enough to get her to launch!!! I absolutely love the build...just want to be able to grab the throttle instead of feathering it.

    When impros suggested 14/21 I was a little leary but went with anyway. Kept reading and then really felt like I was under propped. After riding today...I'm certain I'm feeling the rev limiter.

  4. #4
    butterbean_29512's Avatar
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    Saw a WB2 locally for 3500. Has a 1200 and the 155mm pump. It's sharp looking.

  5. #5
    Just wanted to follow up. I found my problem and I almost hate to admit it. Reading the plug wasn't working...because I had the wrong plugs. I had 3/4 inch length instead of 1/2 length which cause the lean indication. She now has the correct plugs and I'm leaning her out slowly.

    Lesson learned!

  6. #6
    quadzilla's Avatar
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    Quote Originally Posted by vdubspeed View Post
    Just wanted to follow up. I found my problem and I almost hate to admit it. Reading the plug wasn't working...because I had the wrong plugs. I had 3/4 inch length instead of 1/2 length which cause the lean indication. She now has the correct plugs and I'm leaning her out slowly.

    Lesson learned!
    Well done on finding this issue..
    - you could have had yourself chasing a ghost with the wrong plugs installed.

    I still reckon you'll need more prop and less jet going forward..

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