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  1. #1

    Power flat at 3900 rpm /jumps to 4600 rpm

    Hello
    first of all i am new here and i am an absolutely newbie at jet ski's. Please excuse my english but i am from germany and i just live right now in USA.
    So i bought a Polaris SLT 780 (1996) and it runs good so far. The MFD shows about 45mph max speed. So i have the typically POLARIS FUEL issue that i have a full tank but the MFD shows only one line and i get the flashing light. I read a lot about this here and i just wonder that my Jet Ski doesnt change to the LIMP MODE but i have the problem that if i speed up i have a kind of power loss/flat. I mean when i speed up and i reach about 3900 rpm the jet ski doesnt speed up more even if i raise the throttle and if i raise it more i get suddenly a kind of powerboost and the rpm jumps to the 4500-4600 range and i can speed up till 6400 rpm.

    In the picture you can see that the jetski doesnt have the original exhaust and airfilter. Could that cause the problem. The Airfilter doesnt have any inlay i am not sure if it is correct but it looks like because you cant open it.


    I really would appreciate any help


    Markus

    El Paso
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  2. #2
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    Its not actually a problem at all. Most of these 2 strokes do not have a "smooth" powerband, and there is a pronounced "hit" around 4500 where the engine "gets on the pipe" and produces more power. This is more pronounced on some engines, the 780 being one of them. You should be getting 6500-6600 peak RPM.

  3. #3
    Hi Bryan,
    Thx for your answer. It is hard to explain but it is very hard, almost impossible to ride the ski between the 3900 and the 4600 because it is so hard to accelerate. When i reach the 3900 and i just move the throttle lever more forward it hits and jumps to 4500/4600. also when i reduce from above 4600 down. It is the same. Younreally think it is normal? I have no experience because it is my first one. Could it have sth. to do with the racing exhaust and the racing airfilter???


    Thx

  4. #4
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    Its normal. My friends SLT 780 is exactly the same and my 1200s are like that as well. Its a 2 stroke characteristic in general.

  5. #5
    Ok....sounds good. And do you have any idea why my one doesnt go to the LIMP MODE. I have a full tank, only one bar at the MFD and i get the flashing light. When i push set the flashing light goes off for a certain time and comes back again


    Thx

  6. #6
    Banned User
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    Someone may have disconnected the limp mode function just because of the fuel level issue. You can get the floats to fix the fuel gauge for about 30 bucks.

  7. #7
    How can i check it if it is disconnected

  8. #8
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by Mabidopa View Post
    How can i check it if it is disconnected
    Follow the Gray or Tan wire from the CDI, that has a spade connector on the wire end. If it is unplugged from the terminal board, the RPM limiter feature of the CDI is disconnected.

    Normally the Gray or Tan CDI wire connects to the terminal board, where it connects with other Tan wires.

  9. #9
    Hello Bryan,
    as i already mentioned i am totally new to jet ski. What is the CDI and where is it located ( beside the battery) and where is the terminalboard located. Maybe you can explain ittomein the picture in my first thread. Thanks.

    Markus

  10. #10
    BlueFishCrisis's Avatar
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    The electrical box is bolted to a vertical cross member in between. It is a black metal box and has all of the wires going into it. There are 3 hex bolts through the vertical cross member that need to be removed. Disconnect the battery first. Then there are 6 hex key screws that need to be removed to open the electrical box (Ebox). Inside you will see the circuit board that Bryan was referring to....

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