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  1. #1
    thester71's Avatar
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    My "death rev" experience

    Last year I traded an aluminum rowboat/ sea horse motor I had laying around for a 94 sl750. The ski was complete, except the carbs were removed by the owner to be cleaned, but they were included.

    There was no trailer so I went to pick it up in the back of my truck, when we got it home, I took it out of the truck and put it on a rolling stand that I use to move the skis around when there out of the water being worked on.

    After giving the ski a once over, and checking the carbs out, all seemed well, so I installed the carbs, and hooked the garden hose up, and installed a fresh battery. Now it is time to start it up, I pulled the choke knob and cranked it, but after 10 seconds or so it did not fire up, So I figured I would squirt some premix down the carbs, hit the start button again and it fired, but then died quickly so I repeated the process and it fired up again and kept running, but was bogging really bad, so I squeezed the throttle a little bit to see if it would clear up a little and it did, It seemed to start idling up a bit high so I blipped the throttle again to see if the idle would return to normal, and that's were all hell broke loose, instead of idling back down, it started to race wide open. I quickly reached for the kill switch, but to my surprise it didn't kill the engine, so I yanked the lanyard out but still running wide open, in a full panic I yanked all three plug wires off the plugs and the thing was still running wide open, I could not believe it, plug wires off and still screaming wide open! I n a last ditched attempt I pulled on the choke knob and it died out. Wow that was the most rediculous thing I had ever seen, I would have never believed this to be possible if I had not seen this with my own eyes.

    Now that I am getting closer with my pro, I am getting a little nervous to start it up as it has no choke. Has anyone ever had this happen to them before? This engine would surely be junk if the choke had been deleted like it is on my pro. I'm sure I'm not the only person this has ever happened to, the whole event lasted only about 20 seconds or so, but whew it scared the crap out of me.

    After about a half hour or so I got up the nerve to try again, and the ski ran perfect, I put it in the water and it ran great all summer with no problems.


  2. #2
    Hayabusa's Avatar
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    Runaways are not that uncommon but they sure get your attention don't they! Sometimes they are caused by a lean fuel mixture from an air leak, etc. In your case, I would suspect that you induced the problem by putting a little fuel down the carbs in an effort to get it started. The fact that it's now running good, supports my suspicions. That's the reason I do not put fuel down the carbs for a start up. If the fuel system and everything else is working correctly, it should start on its own with minimal cranking.

    I have found that using the choke will kill the motor nearly every time. The inrush of cool fuel along with choking off of the air supply seems to do the trick. On some occasions, just cracking the throttle wide open will stop the runaway.

  3. #3
    blegan's Avatar
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    shut down

    That seems to be the one way to kill a run away motor! With the throttle wide open. Like the previous post said very exciting & will definitely get your heart pounding.

  4. #4
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    You can also kill the motor with a primer. Just need to pump the crap out of it to flood it out.

    Or if the FA is removed, cover the carb tops with your arm. That'll snuff it out.

  5. #5
    thester71's Avatar
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    Quote Originally Posted by xlint89 View Post
    You can also kill the motor with a primer. Just need to pump the crap out of it to flood it out.

    Or if the FA is removed, cover the carb tops with your arm. That'll snuff it out.
    I'm definatly starting the pro with the FA's removed

  6. #6
    Moderator beerdart's Avatar
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    Quote Originally Posted by thester71 View Post
    I'm definatly starting the pro with the FA's removed
    Keep three racket balls handy.

  7. #7
    johnsonmtz's Avatar
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    Quote Originally Posted by thester71 View Post
    ......so I blipped the throttle again to see if the idle would return to normal, and that's were all hell broke loose, instead of idling back down, it started to race wide open. I quickly reached for the kill switch, but to my surprise it didn't kill the engine, so I yanked the lanyard out but still running wide open, in a full panic I yanked all three plug wires off the plugs and the thing was still running wide open, I could not believe it, plug wires off and still screaming wide open! I n a last ditched attempt I pulled on the choke knob and it died out.
    Is this just a case of compression ignition......."dieseling"? In the past I've always just started the ski after the winter and burned off the fogging oil. I've read accounts elsewhere that it's best to pull the plugs and turn the engine over to blow out excess fuel and oil. Then you can put the plugs back in and start the ski. I'm starting to think that's probably a decent thing to do.

    KJ

  8. #8
    thester71's Avatar
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    Quote Originally Posted by johnsonmtz View Post
    Is this just a case of compression ignition......."dieseling"? In the past I've always just started the ski after the winter and burned off the fogging oil. I've read accounts elsewhere that it's best to pull the plugs and turn the engine over to blow out excess fuel and oil. Then you can put the plugs back in and start the ski. I'm starting to think that's probably a decent thing to do.

    KJ
    I'm not sure what caused it, but the motor was running wide open with no lanyard, or plug wires connected , As far as the fogging goes, my motors spend the winter on my work bench, so no need for fogging.

  9. #9
    bowsniper's Avatar
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    Nah,,, I love the HUGE cloud of smoke that comes out.. Kinda like A POLARIS BEAR waking up from winters hibernation!.


    If's theres no oil in the gas, you aint going fast! bing ding a ding a ding a ding a ding..

    Usually run on like that in a car anyways is from the crown of the piston having hot spots of carbon on it that actually ignite the fuel/air mixture before the piston reaches top dead center.

    Or the head has some carbon deposits that can glow like charcoal and act the same way..

  10. #10
    Hayabusa's Avatar
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    Quote Originally Posted by johnsonmtz View Post
    Is this just a case of compression ignition......."dieseling"? In the past I've always just started the ski after the winter and burned off the fogging oil. I've read accounts elsewhere that it's best to pull the plugs and turn the engine over to blow out excess fuel and oil. Then you can put the plugs back in and start the ski. I'm starting to think that's probably a decent thing to do.

    KJ

    I just start my skis up after winter storage without pulling the plugs. The fogging oil will just burn off with no problems that I've ever seen. Also, many people will change the spark plugs believing the fogging oil will cause a problem with them. In my opinion, it's a waste of money. Spark plugs are changed far more often than needed and unless the electrode looks worn or you're having some problem you think is plug related, don't waste your money on new ones.

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