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  1. #1

    99 SLH 700 Running Rich

    Let me start. this is a recent new top end, carbs rebuilt, electrical system updated and new fuel lines. I had alot of problems getting to the point I'm at now and now hopefully one more hurdle. due to frustation I've ran this ski the end of the summer approx 10 hours. My problem is that it bogs at low end - sometimes I can feather thru it other times I can quickly hit the choke (just real quick or it dies) and I get thru the low rpms and I'm up and running. Now if i shut it down or come to a idle for a minute or so no problem the engine only bogs ever so slightly and I'm up and running. If I stop the engine for a few minutes or longer i go thru the bogs issue again. Now it hasn't really bothered me all that much but I'm worried that I will eventaully screw something up. I've noticed that the plugs are showing signs that the engine is running very rich. I'm running premix 40:1. Any suugestions on leaning it out. I'm think this is my problem.


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Carb rebuild - how carefully and completely was this done?

    Have you checked for air leaks inside the engine (leak down test)?

    Carb and intake gaskets all 100% good?

    What settings are the carbs at?

    Pre-mixed oil+gas, or oil injection still operational?

  3. #3
    No leak test done.

    All new gaskets in carb and engine'

    Only carb setting is low idle screws (in for lean and out for rich) I have them now at a 1/4 turn in an attempt to lean it up.

    Oil injection removed.

    If I continue to ride this ski do you think I'll have more problems?

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    What exactly makes you suspect it is running rich at low RPM?

    You may want to try spraying ether engine starting fluid around the crank case and intake/carb gaskets and the PTO crank seal while the engine is idling. If the RPM rises when you spray an area, then the engine is sucking the ether in though an air leak.

    Pulling the choke to improve things usually implies that the engine is running lean, and the choke reduces air flow, making the fuel+air mixture richer.

    Did you cap off the oil supply nipples on the intakes, when the engine was converted to pre-mix?
    Are those caps air tight?

  5. #5
    Well I was basing the running rich on the look of the spark plugs - very dark to black and wet. I did cap of the injector line on the carb but I can't say they are air tight. I'll try the ether thing after double checking the oil block off caps. The ski does run great after getting past the bog just after idle- the jet screams and it a blast to ride.

    Thanks for the help.

  6. #6
    Rasta Mon Condoms We Be Jammin!!!!! TxVirageTx's Avatar
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    premix

    going from injection to premix will lean out the idle.more oil in the same space means less fuel.then you leaned out the setting on the low speed??whatever the factory setting is add an 1/8 or a 1/4 turn to it

  7. #7
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    Quote Originally Posted by polaris 700cc View Post
    Well I was basing the running rich on the look of the spark plugs - very dark to black and wet. .
    Is this after running it on the trailer ?

    Check the piston wash to determine rich/lean.
    If you are going to look at the plugs,you need to look at them when the problem occurs.If the problem occurs after idling for a few minutes in the water,shut it off and check plugs. Please post pictures of them.

  8. #8
    No this is after running the ski most of the day. Each time I take it out i recheck the plugs and they look rich. Like I said the ski idles good in the water and runs great just after say 1/8 throttle just getting past the initial low throttle is a sticking point and it only happpens when the ski is off for a couple minutes or so, now when I'm riding and momentarilly go to idle and goose it again theres' no problem (no bog) just the initial start after being off for a few minutes or at idle for a few minutes. Once I'm through it no problem. Just got a little tired of messing with it and just decided to run the ski the rest of the summer like it is. Now I'm a little concerned if I'm actually screwing it up.

  9. #9
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by polaris 700cc View Post
    ...the ski idles good in the water and runs great

    just after say 1/8 throttle just getting past the initial low throttle is a sticking point and it only happens when the ski is off for a couple minutes or so,

    now when I'm riding and momentarily go to idle and goose it again there's' no problem (no bog)

    just the initial start after being off for a few minutes or at idle for a few minutes.

    Once I'm through it no problem. Just got a little tired of messing with it and just decided to run the ski the rest of the summer like it is. Now I'm a little concerned if I'm actually screwing it up.
    Next time it is cold, or has been sitting, prime some fuel down the carb throats. A few squirts
    Put the flame arrestor back on.

    Start it up in the water, and see if it pulls strongly from idle right away.

    If it makes it easier, you can do this test with it strapped to the trailer on the launch ramp, backed into the water.

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

    sounds like this to me.you ride it around,anytime its not allowed to idle it runs great,good throttle response.if its allowed to idle for longer than 5 seconds it starts acting up.if its rich it will sound like its missing a couple of beats.if its lean it stalls.when the throttle goes wot you fill the crankcase with the mixture based on the main jets.when you let off that mixture takes a while to change from a o'kay or rich mixture to a lean mixture, a couple of seconds.then after those couple of seconds the mixture in the crankcase is lean,you hit the throttle and it won't respond right.

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