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  1. #1

    2-cycle Polaris overheating

    Hello Polaris gurus!

    I am a first time PWC owner and first time to this forum. I just bought a 2001 Virage with a 2-cycle two cylinder single carb engine that has 50 hours total. I quickly found that this is The Polaris Forum I went through all the archived threads on overheating but could not find quite the same symptoms as mine, so hoping to get some hints from the experts...

    My engine starts up great and runs great initially on all RPMs. If I go slow (3000-4000RPMs) it will run without any problems for hours. If I WOT it while simply riding straight, the engine will run great (6500 RPMs) for a minute or so (with water speed around 50MPH), but then it suddenly shuts down within a couple of seconds. No "HOT" message on the LCD and no other symptoms. If I wait a couple of minutes, it will start again. But starting it right away may require a lot of cranking.
    Another interesting thing - when it does start up after dying like this, it will shut down again even if I don't WOT the engine. I mean, if I go full throttle it will die very quickly (in less than a minute), but if I go slowly at 3000 RPMs, it will shut down after a few minutes.

    My compression is 145 in both cylinders, spark plugs and spark wires are brand new, the thermostat and pop-off valve are clean, both the incoming and outgoing cooling water hoses seem to be clean, and the tiny screen in the exhaust hose is clean too... I did purge the fuel tank and oil tank and filled them up. I have not tried flushing the cooling system or any other tricky procedures. I suspect overheating, but I don't know how to confirm this. Is there a temperature sensor on this engine? I could not easily find it...

    I'll greatly appreciate any hints on this!


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Welcome

    Click on my signature for useful links.

    When the engine is running normally, you should be able to put your hand on the engine sides or top without burning your hand. If you can hold your hand on it it for a few seconds, it is not too hot.

    If water drops sizzle on the engine, or it is simply too hot to touch, then it is indeed overheating. Same for the exhaust manifold - it has a water jacket, and should be touchable.

    I suspect your engine is running lean, and you are seizing an overheated piston inside the cylinder

    Have a look at this web page.
    If the original gray Temp fuel hoses are still on there, that might be part of the problem.

    Have the carburetors been cleaned or rebuilt recently?

    If a carb is partially clogged inside, or the carb screws are set incorrectly, the engine can still run and produce good power, but the inadequate fuel delivery into the cylinder will cause the piston to get hotter than normal.

    If this condition is not corrected, the piston will soon melt a hole right through, or otherwise self destruct.

    The compression numbers you reported indicate that it may not be too late for your engine, but you still need to figure out what the problem cause is, and fix it before you do any further riding.

  3. #3
    Thank you K447!
    This is extremely helpful. I am going to replace the fuel lines right away and try to measure the engine temperature.
    My carburetor was professionally rebuilt 6 months ago. The previous owner had a $300 receipt for this, and I noticed that the shop had to test the ski on the lake twice. They were probably chasing the same problem but failed to fix it by messing with the carb
    Can you please give me a hint on what is the best method for adjusting the carburetor? Am I supposed to ride the ski with the seat removed and adjust the carburetor "on the fly"? It sounds difficult to be managing the throttle, the steering, and work on the carburetor at the same time...
    Also, is there any simple way to confirm that I have enough water flowing through my cooling system?
    Thanks a lot for sharing your wisdom!

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by Dawg View Post
    ...I am going to replace the fuel lines right away and try to measure the engine temperature.

    My carburetor was professionally rebuilt 6 months ago. The previous owner had a $300 receipt for this, and I noticed that the shop had to test the ski on the lake twice. They were probably chasing the same problem but failed to fix it by messing with the carb


    Can you please give me a hint on what is the best method for adjusting the carburetor? Am I supposed to ride the ski with the seat removed and adjust the carburetor "on the fly"? It sounds difficult to be managing the throttle, the steering, and work on the carburetor at the same time...

    Also, is there any simple way to confirm that I have enough water flowing through my cooling system?
    Thanks a lot for sharing your wisdom!
    If you can hold your hand on the engine after a good run, you have enough water flow.

    There is a separate small mesh screen and small nozzle fitting for injecting water into the exhaust. Remove and check those, just in case.

    If the previous shop did not replace the gray Tempo fuel lines, then some goop from those lines may now be stuck inside your carbs. So the carbs would need to be opened up and cleaned. And replace those fuel lines.

    If the shop did not properly clean the carbs during the rebuild, then they will need to be done again.

    Also make sure the fuel filter is new, and the water separator is clean (if you have one).

    Change the oil filter while you are at it, and replace those eight year old oil lines. Filters, hoses and clamps are cheap, engine rebuilds are not.

    You want to be able to say with confidence that the fuel system is 100% good, all the way from the fuel tank through the carbs.

    Then you can work on the fine tuning.

    There is a very helpful thread called "Tuning for girls', or something like that (I think it was posted by Randy from Watcon).

    Start with the factory carb settings, and then go from there.

    You may find the factory settings are just fine, once the carbs are clean, and the fuel lines are good.

  5. #5

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    The tuning info is in the tech tip section,

    http://www.greenhulk.net/forums/showthread.php?t=15473



    Then you can work on the fine tuning.

    There is a very helpful thread called "Tuning for girls', or something like that (I think it was posted by Randy from Watcon).

    Start with the factory carb settings, and then go from there.

    You may find the factory settings are just fine, once the carbs are clean, and the fuel lines are good.[/quote]

  6. #6
    K447, thanks a lot for educating me on the Tempo fuel lines. Apparently, all of my fuel lines were Tempo with lots of green goop inside. I spent a couple of hours yesterday, got all the fuel lines replaced along with the fuel filter. I also bought an infrared thermometer and brought it to the lake. Apparently, my engine does not get very hot. The maximum temperature that I've seen was 50 degrees celcium. The exhaust pipe is even cooler... So, I guess my overheating theory is not worth a crap
    I just took off the carburetor and going to clean it up... I guess, this is my next best shot?

  7. #7
    AWA Member 32DegH2O's Avatar
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    Your compression is higher than stock so I'm betting someone put some aftermarket high compression heads on it. This will cause a little different jetting for the carb from stock and may be the cause of the slight lean condition. A lean condition doesn't always cause an over heated engine, it can become a lubrication issue that can cause a slight seizure. Compare the jets to what is called out in the service manual to see if there was a change made.

  8. #8
    I just opened up the carburetor (Keihin CDK2) and found that the tiny fuel filter that's inside the carb is completely clogged. Most likely, the stuff that came from the Tempo fuel lines. So, I am full of hope that this will explain why my engine was shutting down.
    One thing surprised me in the carburetor - according to the disassembly instructions that I found on this site, this carb should have both low speed screw and high speed screw. In my case, the High Speed Screw is physically missing. The hole for it is there, but unlike the hole for the Low Speed Screw, I am not able to pump any air or fluid through it. So, it really looks like my carb was not supposed to have the high speed screw. Is it possible?
    Thanks guys for educating me on this stuff! No way I would be able to figure everything out without this forum...

  9. #9
    I did one more test on the lake this morning, and even with the clean carburetor the engine would still shut down after riding for a while and have a hard time starting after that. My overheating theory is out of the window at this point - the maximum temperature that I was able to measure was 60 degrees celcium.

    I am starting to suspect the fuel pump. Does anybody know an easy way to check if it is working reasonably well?

  10. #10
    Rasta Mon Condoms We Be Jammin!!!!! TxVirageTx's Avatar
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    2 things

    pull the brass fitting at the top of the red pipe and see if the screen is clogged.with all the green goop the return could be blocked,pull the return hose off the carb,start it and see if gas dribbles out the brass fitting.if it doesn't,pull the carb,remove the metering block,and blow thru at the brass fitting using about 100 psi.that'll clear the green gunkus out

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