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  1. #1
    Race, wreck, repeat delagem's Avatar
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    Electric water pump?

    This isn't for a Polaris, but I thought you guys would have the best suggestions on my problem.

    The Amanda has a 100cc 2 stroke single motor, air cooled. It's going to be slow. Like 7mph slow. So I'm on the fence about doing some non-permanent mods in order to bolt a Kawi 650 twin motor in there.

    I say non permanent, so I'm not going to chop out the bottom, and graft in a pump. It appears to be pretty simple to adapt the centrifugal clutch onto a Kawi. 4 motor mounts, a custom bed plate, battery tray, and I should be in business.

    The one sticking point? The cooling. The Amanda uses a propeller and rudder, no jet drive, hence, no pump to tap for cooling water. How can I get water, without fail, only when the motor is running? I don't want a switch, eventually that will be forgotten.

    Or does anyone have any other ideas?

    Please don't flame me for not wanting to keep it stock. The point is to get it out there, and ride it, but retain the ability to go back to stock.
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  2. #2
    PolarisNut's Avatar
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    Whats the stator output on that Kawi 650? I bet it's not enough to power a decent electric water pump. Eventually, the pump will run the battery down, if the stator can't keep up.

  3. #3
    Click avatar for tech links/info, donation request K447's Avatar
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    What do the Kawi land engines (motorcycle or ATV?) use for cooling?

    Mechanical water pump at the PTO?

    Electrical is easy enough, I think. Just install a battery combiner without the second battery. Use the second battery connection to power the electric water pump. A combiner is basically a voltage controlled switch. When the charging system bumps the battery voltage up above 13.x volts the relay inside the combiner closes and links the two power cables together.

    A combiner relay has the Amp capacity to handle whatever electric pump you might choose. The key is that the the Kawi alternator must be able to hold the voltage up at idle RPM.

    Another approach (depending on how the Kawi alternator works) is to use an RPM triggered module switch. Polaris has one in the LR-50 and LR-52. Unlike most of the other/later Polaris LR modules, the LR-50/52 simply monitors the Yellow wire for AC signal, then switches/supplies battery power to the Orange wire.

    The LR-50 and LR-52 do not provide a voltage regulator function for the alternator, which is why they are unique and can be used for simple engine-is-running power switching. The LR-52 also has a special low voltage output for the analog fuel gauge, which you would not utilize.

    You could run the Orange wire output directly to your water cooling pump, or through a relay to minimize the current the LR-50/52 module must provide.

    Hint: You could also use the LR-50 or LR-52 to power a bilge pump on the MSX-140, which doesn't normally have an Orange wire output.

    ---------- Post added at 01:23 PM ---------- Previous post was at 01:13 PM ----------

    Most bilge type pumps do poorly if there is much back pressure involved. I imagine you want a positive displacement type water pump that can deliver flow with some PSI.

  4. #4
    Race, wreck, repeat delagem's Avatar
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    Ok, that sounds like a great idea! I was thinking of a simple relay, an LR sounds even better.

    For a pump I was thinking of a livewell style setup, with a clamshell thru-hull penetration facing forward, which would help to stuff the pump when moving. I'm just guessing, but it looks like this thing draws less than 3" when on plane, water starvation and priming might be an issue without the clamshell.

    I know the Kawi 650 motor will handle 1 and even 2 bilge pumps, a common mod on standups ridden in the surf. It would be simple enough to check amp draw to be sure the livewell pump wouldn't run the battery down. More research to do!

    Anyone ever checked their cooling flow, in gallons per minute, before?

    Of course, there is another option. My machine appears to be a model 100 (the decal is gone, but you can still see the ghosting "100" in the paint on the tailfin. They also made a model 200, rumored to be a 200cc twin, also air-cooled. Of course, I've never even seen that model, much less an engine for sale.
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  5. #5
    PolarisNut's Avatar
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    Keith - That's IF the stator can provide the current...otherwise, you will be slowly draining the battery, and eventually stranded. If the stator only outputs 100W (8.3A), but the electric pump uses 150W (12.5A), you can see what will happen. The stator still needs reserve power to run the ignition system as well.

    I can tell you for sure that a 500gph bilge pump won't provide the proper flow to cool a 650cc twin at WOT. Bilge pumps and live well pumps don't pump efficiently with any "head"...or restriction...which a cooling system will have. You have to force the cooling water through the engine with some pressure, otherwise, you will end up with hot spots and localized boiling. That is why the cooling systems are pressurized on skis.

    EDIT: Just saw Keith said the same thing about bilge pumps.

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by K447 View Post
    ...The key is that the the Kawi alternator must be able to hold the voltage up at idle RPM....

    ... Most bilge type pumps do poorly if there is much back pressure involved. I imagine you want a positive displacement type water pump that can deliver flow with some PSI.
    Quote Originally Posted by PolarisNut View Post
    ...That's IF the stator can provide the current...otherwise, you will be slowly draining the battery, and eventually stranded. If the stator only outputs 100W (8.3A), but the electric pump uses 150W (12.5A), you can see what will happen. The stator still needs reserve power to run the ignition system as well.

    ... You have to force the cooling water through the engine with some pressure, otherwise, you will end up with hot spots and localized boiling. That is why the cooling systems are pressurized on skis.

    EDIT: Just saw Keith said the same thing about bilge pumps.
    You are correct about the current draw.

    If the charging system is able to hold the voltage up (above 13.5 volts) at idle (and every other RPM) then by definition it is able to provide the Amps the electric water pump is demanding.

    Voltage sag when the electric pump is operating is a strong indication that the electrical system cannot fully supply the power needed.

    ---------- Post added at 05:37 PM ---------- Previous post was at 05:27 PM ----------

    Quote Originally Posted by delagem View Post
    ... Anyone ever checked their cooling flow, in gallons per minute ...
    I don't have pressure or flow numbers for you, but if you think about the Yamaha 'visibility spout' on the early waverunner models, that should give you an idea of the pressure and volume available from the jet pump for cooling water flow. Or the pissers on your own watercraft

    The Yamaha visibility spout taps into the same area on the pump exit nozzle as the actual water cooling pickup. It shoots quite high when the engine is revving, so there is significant pressure and flow available. I would expect pressures well above 10 PSI.


  7. #7
    johnsonmtz's Avatar
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    Quote Originally Posted by delagem View Post
    For a pump I was thinking of a livewell style setup, with a clamshell thru-hull penetration facing forward, which would help to stuff the pump when moving. I'm just guessing, but it looks like this thing draws less than 3" when on plane, water starvation and priming might be an issue without the clamshell.
    Rather than a clamshell, why not model the water intake after the intake screens found on an outboard motor? You could fabricate a teardrop shaped cone with intake screens fitted on both sides and place it to one side of the prop. Then you could just have a hose protrude through the hull to the inlet side of the electric pump

  8. #8
    Moderator beerdart's Avatar
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    You may be able to use a pitot tube on the rudder like the surface drive boats.

  9. #9
    Click avatar for tech links/info, donation request K447's Avatar
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    Someone on GH had a prop ski conversion that had a ram effect metal tube running down the back side of the rudder, then curved forward at the bottom to face the water stream. Flexible hose off the top of the rudder tube fed the cooling system.

    Don't seem to be able to find the photo at the moment.

    It kept the intake as low as possible and out of the way of prop wash. I suppose it would be subject to potential clogging, as is any water intake that is below the hull.

    If you use a positive displacement type water pump, it will draw suction even if there is air in the feed tube. Then you don't need to worry about priming the pump. Just as long as there is water at the inlet when the hull is moving, it will work.

  10. #10
    Race, wreck, repeat delagem's Avatar
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    Back from reading on David Bunn's 106mph propski, used an electric pump for slow speeds, and rudder mounted pickup tubes, for high speeds. Compared to that crazy machine, all of my speeds will be slow speeds!

    If charging the battery becomes an issue, here's a thought... The Kawi 650 has enough room to mount a MUCH larger stator, with a greatly improved charging system. The stator from the Jetmate! Of which I have one, in need of a rewind from JetSkiSolutions. So at least there's an option.

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