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  1. #1

    Think i have a bad reed valve? backfiring though middle carb. 95 slt 750

    Been lurking these forums for a long long time.. finally took the 2 minutes to register

    Ok so last year suddenly my 95 slt 750 lost power... wouldnt get up on plane at all.. so looking at the carbs when trying to start it the middle cylinder i see a lot of smoke coming through it... I cant even get it started now this year.. last year it would start but No power... Checked compression first two cylinders are 120-125 psi.. the 3rd cylinder was down just below 100. obviously the third cylinder is going to need attention but i do not believe it is causing my problem and i dont want to go internal on this engine now as to lose too much summer time... going to install a triple outlet pump (where to buy????) now and redo fuel lines. Should have done it long ago as i knew of the single pump problem.... ah well.

    broken reed? that is what i concluded although i havnt taken it apart yet... the compression in that cylinder is good and its definetely the 2nd cyinder with smoke blowing up through it. neither of the other cylinders show these symptoms.

    Also have a cavitating pump that im going to be taking apart at the same time... This is just what you get for letting people have a good time with your ski... Oh i need to shut this off before i land it on the beach and not let it run for 20 seconds while you run at me yelling to shut it off?? didnt know that... yea only told you 20 times to shut it off 5 feet before the beach as you cant steer without thrust but cant suck up sand....

    after i fix it only experienced riders allowed sorry for the rant lol.... just sure some of you have had the same thing happen.


  2. #2
    Polarisitis loonatik's Avatar
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    Welcome to GH!

    Quote Originally Posted by popoman View Post
    ... Should have done it long ago ...
    Yes, now is good time go through all routine maintenance and check things that you've suspected.
    As each season goes by, those screws and nuts will be tougher to remove.
    Last edited by loonatik; 06-27-2011 at 08:33 PM. Reason: will = will be

  3. #3
    johnsonmtz's Avatar
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    Quote Originally Posted by popoman View Post
    Ok so last year suddenly my 95 slt 750 lost power..

    when trying to start it the middle cylinder i see a lot of smoke coming through it..

    Checked compression first two cylinders are 120-125 psi.. the 3rd cylinder was down just below 100. obviously the third cylinder is going to need attention but i do not believe it is causing my problem and i dont want to go internal on this engine now as to lose too much summer time...

    going to install a triple outlet pump (where to buy????) now and redo fuel lines.

    broken reed? that is what i concluded although i havnt taken it apart yet...

    Also have a cavitating pump that im going to be taking apart at the same time...
    Low compression on PTO (closest to the back) sure can cause poor starting conditions. That is the part of the crankcase where pulse is generated to operate the fuel pump.

    John Zigler at Rock County Jet Ski http://rockcountyjetski.webs.com/polarisenginefuel.htm is a great source for genuine Mikuni fuel parts.

    Here's what you need to do:

    1) Pull the pulse line off the fuel pump plug it, then retry the compression test. I can't say for certain, but if your old fuel pump diaphragm is ruptured it might allow some of the air charge in that cylinder escape and cause the lower compression reading. If you still get the lower reading after doing this, you have cylinder problems that need attention.

    2) Pull the head on PTO and have a look at the cylinder. If it the wall is okay, you might get by with just honing the cylinder and installing new rings. At worst you'll need to oversize by 0.25mm and install a new piston.

    3) Get that 3-outlet pump installed with all new fuel lines.

    4) While you're at it, you might as well rebuild the carbs with genuine Mikuni kits to make sure everything is on the up and up.

    5) Check the impeller for spec in the wear ring. It's possible the ring needs replaced or the impeller re-worked.

    KJ

  4. #4
    if i take off the PTO head am i going to need a new gaskets? can i get the pto head off without taking off the water coolant bar? dont know the exact name of it... lol

    wear ring and impeller clearance specs i should look for?

    Also forgot to mention... checking the ski today i noticed after cranking that a liitle bit of fuel would spray out of only the mag cylinder carb until i loosened the gas cap and then it stoped. didnt release a ton of pressure when i took the cap off... i have surely seen a lot more pressure coming out of this ski since we have owned it..( since 1995... example... low fuel sitting in the sun... sometimes the cap will pop off when loosened..) so would this show anything wrong with pump diaphragm? never seen a vacuum in the fuel tank.

    thanks a lot guys!

  5. #5
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    Add to your list of things to do: replace the fuel tank venting check valves. That should solve the fuel tank excess air pressure problem.

    See my signature links for more info

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