Results 1 to 6 of 6
  1. #1

    Join Date
    Jun 2015
    Location
    Louisburg, KS
    Posts
    12

    1996 Polris 780SL rpms limited @ 4900

    Hey guys I'm new to the forum but have done a lot of research from this site. I have a 96 780 so we were out riding and all of a sudden it wouldn't rev past 4900. Here's a list of what I've done to no avail let me know if I'm missing something.

    -checked that it's not in limp mode
    -replaces all fuel lines & fuel pump
    -rebuilt carb with mikuni rebuild kit
    -replaced starter and battery
    -converted to premix
    -unplugged mfd
    -bypassed fuel selector
    -remove jet pump to ensure impeller spins freely
    -fine tuned carb needles
    -replaced pop off fuel vent
    -replaced all electronics from brain box from another working 780

    it does the same thing on water and on the hose. Any ideas or tips would be greatly appreciated. I'm unable to do a compression test with a gauge until Monday, but by holding a finger over the spark plug hole all three cylinders blew my finger off pretty forcefully. It starts idles and runs with no problem up until 4900 rpm then it's like it hits a wall.


  2. #2
    BlueFishCrisis's Avatar
    Join Date
    Aug 2011
    Location
    Medina, Ohio, United States
    Posts
    5,039
    +1
    143
    Welcome! Did you try disconnecting the rev limiter wire from the CDI? If you did, than it is possible that the stator is bad. Had a similar issue with an SL780. Everything checked out including the ohm readings on the stator. Replaced it and worked great.....

  3. +1 by:


  4. #3

    Join Date
    Jun 2015
    Location
    Louisburg, KS
    Posts
    12
    Ya I tried disconnecting rev limiter/limp mode wire. I'll try the stator next I won't be able to work on it again until Monday but I'll give an update when I get it replaced thanks for the help!

  5. #4
    Myself's Avatar
    Join Date
    May 2007
    Location
    North Central Arkansas
    Posts
    3,196
    +1
    172
    I agree with BlueFish, I've changed out a couple Polaris and other brands where the stator ohms out just fine but won't give any high RPM.

  6. #5

    Join Date
    Jun 2015
    Location
    Louisburg, KS
    Posts
    12
    Ok update the stator fixed it runs great. Now out on the water it starts and runs awesome with just me on it but with me and the gf on it its pretty slow to get to full speed way slower than my 750 with both of us on it. It doesn't seem like a carb issue it reaches max rpm then feels like it takes a few seconds before taking off like a clutch or something is slipping. The drive shaft looks straight to me and it doesn't vibrate like I think it would if it was bent. Any other ideas? And I appreciate all the help! One of these days we'll get it running like new lol

  7. #6
    Click avatar for tech links/info K447's Avatar
    Join Date
    Jul 2007
    Location
    near Toronto, Canada
    Posts
    38,676
    +1
    1,635
    Quote Originally Posted by Muddinpolari12 View Post
    Ok update the stator fixed it runs great. Now out on the water it starts and runs awesome with just me on it but with me and the gf on it its pretty slow to get to full speed way slower than my 750 with both of us on it. It doesn't seem like a carb issue it reaches max rpm then feels like it takes a few seconds before taking off like a clutch or something is slipping. The drive shaft looks straight to me and it doesn't vibrate ...
    Jet pump ventilation or cavitation, sounds like.

    Ventilation is when there are air leaks into the jet pump from forward of the impeller. It is critical that there be no gaps in the sealant between ride plate and hull, pump shoe or the intake grate. The jet pump base is also supposed to be sealed to the hull. If your jet pump has an extension wear ring then it should be sealed to the pump base where the two fit together.

    Everything in front of the impeller is under suction during hard acceleration from idle speeds. Air leaks into the jet pump allow air bubbles which cause the jet pump to reduce thrust.

    Cavitation happens when the impeller blades are dinged or bent, or the stator vanes are damaged. This causes turbulence and localized disruption of the water flow through the jet pump and reduces thrust.

    It is also important that the outer edges of the impeller blades be very close gap to the surrounding wear ring. Maximum blade gap allowed is 0.020 inches but 0.010 inches or less is preferred.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. 2004 Octane RPM limiter elimination.
    By pato_jones in forum Polaris Open Discussion
    Replies: 2
    Last Post: 07-05-2008, 08:11 PM
  2. RPM Limiter?
    By laxidiot87 in forum Polaris How To & FAQs
    Replies: 3
    Last Post: 07-03-2008, 01:08 PM
  3. reverse rpm limit 03 msx 140
    By boosis in forum MSX/Matrix
    Replies: 1
    Last Post: 10-14-2007, 05:09 PM
  4. RXP RPM Limiting Question
    By Jarrett in forum 4-Tec Performance
    Replies: 40
    Last Post: 07-20-2007, 06:58 PM
  5. 06's RPM Limited For Breakin?
    By AMG ETR in forum Sea Doo Open Discussion
    Replies: 12
    Last Post: 05-21-2006, 04:01 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •