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  1. #11
    robisthemantis's Avatar
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    Check for air leaks, spraying some carb clean or similar around the carb gaskets etc will tell you if they’re leaking by the change in engine note.
    Anyway good luck!

  2. #12

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    Quote Originally Posted by robisthemantis View Post
    Check for air leaks, spraying some carb clean or similar around the carb gaskets etc will tell you if they’re leaking by the change in engine note.
    Anyway good luck!
    I love that trick. I used it to find numerous vacuum leaks on a 72 Chevelle I had here In the shop. The thing is... we never even touched the carbs before this started. Going through the carbs I found corrosion intrusion, possibly causing air leaks.


  3. #13
    jgustman's Avatar
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    I think youíre pretty much done too, except for adding more angle to the ride plate. I have an Ď08 with a pump wedge, 145# compression riva heads, v-force reed setup, d-plate, stock sound supression, ross nemoís sonic boom modded throttle bodies so all air intake is removed, Jimís modded plate at .950, maxed out with the pump wedge, trim tabs at .067Ē, 800 grate, 14/20 tweaked up slightly, pump shoe set at .070Ē up, pump shoe holes filled, pump tunnel reinforced, r&d fuel controller, pump water spout blended and plugged. Air mods done to the side intakes. With the storage bucket out oon a cool day it turns 7220-7230 rpm on a PET-2100 tachometer at mid 74mph on low fuel. I was having a pump overstuff problem at that speed with the pump shoe holes modified to pull the shoe tight against the transom, the hull would suddenly pop up higher out of the water and the nose would start bouncing, I added the pump pressure relief mod, no more pump stuffing but lost a few tenths of speed. I just pulled the pump wedge out and worked the plate some more to get angle to 1.08 and itís pretty much maxed out for angle without grinding too much off the plate and making it too thin and wrecking it. I donít think the wedge helped at all as I was hitting that speed prior to putting it on. I have not had time to retest the change in setup without the pump wedge. Any less than .067Ē added to the trim tabs is a porpoising nightmare. I am at 1,050 feet elevation as well. I had a gp1200r that hit 75.6 on a ďperfect air dayĒ. It was turning 7350 rpm that day with a very similar setup with all holes filled except for the plate holes. With the shorter pump setup you could angle the hell out of the plate, it is obvious now that it had way more plate angle and I think thatís what limits the newer gp1300r with the pump extension limiting plate angle, but it handles a lot better at similar speeds.

  4. #14
    jgustman's Avatar
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    I must add that I relocated the pump shoe back to normal when adding the pump pressure relief mod, so I don’t know if it even needed pressure relief now, I will plug it and see. Also running jetworks mod as well. Make sure the intake grate is blueprinted to the shoe also, no edges catching water coming in and no edges catching water at the front of the ride plate as well. I assume you’re running metal trim tabs, if not you need to. A am also running a 4 degree advance keyway on the flywheel.
    Last edited by jgustman; 09-27-2020 at 10:43 AM.

  5. #15
    robisthemantis's Avatar
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    Cheers for the feedback jgustman!

    Interesting what you mentioned about the pump wedge not making any speed- maybe it’s designed for use on boats with un modified ride plates or something.

    Definitely let me know if you end up removing it and it helps or not.

    No currently I’m just running the oem plastic tabs, I’ll order some.

    Plenty for me to do from all the info yourself and the other guys that have answered this post no I just need to make some time and get back under that boat, I’ll let you know how I get on.

  6. #16
    Adam's Avatar
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    An 800 grate will get you past 71mph , your choice but an 800 grate is still very good in the ocean .


  7. #17

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    We acquired an 800 grate for ours. Over Memorial weekend I went out and the lake was busy AF. Granted, it’s a tight chop, but I was wide open in 1-2 footers and the pump never unloaded. Needless to say, it was a blast!!


  8. #18
    jgustman's Avatar
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    Quote Originally Posted by robisthemantis View Post
    Cheers for the feedback jgustman!

    Interesting what you mentioned about the pump wedge not making any speed- maybe itís designed for use on boats with un modified ride plates or something.

    Definitely let me know if you end up removing it and it helps or not.

    No currently Iím just running the oem plastic tabs, Iíll order some.

    Plenty for me to do from all the info yourself and the other guys that have answered this post no I just need to make some time and get back under that boat, Iíll let you know how I get on.

    Looks like my testing is done for the year. Never got a run in to test the changes...The lake I run on is so low I sucked up rocks and wrecked the impeller just idling near the dock and there is moss weed growing all over, so even if I do attempt a run it will probably not go well...

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