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  1. #1
    PWCToday Newbie
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    No power until water flows from pisser

    So I have an X2 that has a westcoast pipe on it and I'm just curious why the ski feels like it has no bottom end power until water starts to flow from the pisser. It's not a problem at all. It only takes a couple seconds for the water to flow through the cooling system and make things nice an crisp... I just want to know why.

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  2. #2
    Resident Guru 2strokesmoke's Avatar
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    Re: No power until water flows from pisser

    High Performance 2-Stroke Exhaust 101

    The purpose of an "expansion chamber" is to return to the exhaust port a negative sound wave then a positive sound wave at precisely the right time. If the pressure wave returns too late, you lose some of the fresh fuel charge in the combustion chamber and performance. If the wave returns too soon, it pushes hot exhaust gas back into the combustion chamber contaminating the fresh charge and creating hot spots on the piston.

    This is from http://www.factorypipe.com/t_pipetuning.php

    Prior to the Pisser " pissing" the wave is returning the charge too soon, resulting in less power. Once the system is full of water and injecting water into the exhaust stream and "pissing" over board, the sonic wave is now returning at the "right" time. WestCoast pipes with the smaller 4.5" chamber need water to perform effectively... in some set ups.

    I'm sure there are much more detail explanations out there with pics and/or videos. Hopefully someone more experienced will chime in.
    Last edited by 2strokesmoke; 11-10-2017 at 02:28 PM.

  3. #3
    PWCToday.com Is My Home Away From Home Myself's Avatar
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    Re: No power until water flows from pisser

    And besides all that technical stuff you should never be on the throttle hard until it runs for a bit anyway, which is plenty of time for the cooling system to fill.
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  4. #4
    Frequent Poster AirJunky's Avatar
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    Re: No power until water flows from pisser

    Quote Originally Posted by Myself View Post
    And besides all that technical stuff you should never be on the throttle hard until it runs for a bit anyway, which is plenty of time for the cooling system to fill.
    Thats kind of what I was thinking. I usually run the thing for 15 or 20 seconds near the shore, then idle out to deeper water before I get on it..... by that time the pisser is goin good.
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  5. #5
    PWCToday Newbie king895's Avatar
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    Re: No power until water flows from pisser

    Thanks 2strokesmoke, I totally get how the expansion chamber works, I guess I just didn't relize how instrumental the water volume was in the timing of the charge. Thanks for clearing that up for me though. As for the warm up, I give her a start with the hood off on a stand in the water for about 10 to 15 seconds before I drop her in the water. This warms the motor up plenty but doesn't draw water. I'm very careful and conscious of my motor.

  6. #6
    Top Dog Benflynn's Avatar
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    Re: No power until water flows from pisser

    My sj won't piss at idle

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