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  1. #1

    slow slow take off

    I checked carb adjustment for the first time on my boat from what I have been told they are mikuni 44's both high and low are set at 1-1/2 turns out. engine is a 657x with rosser head and r&d exhaust. this boat has a slower hole shot than my 30 hp jon boat pushing the same weight. do you think that this high speed screw adjustment is the problem with hole shot. I am just trying to get the best take off that I can get out of this set up. when I got this boat it had isues and I am trying to take care of this last one. does any one have a lot of experience in adjusting these carbs. where would you start at and what would be your next step. please remember that this what I have to work with till I can do beter. so what kind of adjustments would you do to this set up. if I can even get close to the same hole shot my 30 hp jon boat has pushing the same weight I would be happy. thank you all for the help


  2. #2
    lextoy's Avatar
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    need more info...
    aftermarket F/A's???
    primer kit??
    does it hesitiate and then take off fast??
    or bog down the whole way thru the pawerband??
    what max rpm's are you turning?
    what color are plugs after you run the ski for a few minutes?? oily black or light brown, or light grey??
    does it idle ok??

  3. #3
    Quote Originally Posted by lextoy View Post
    need more info...
    aftermarket F/A's???
    primer kit??
    does it hesitiate and then take off fast??
    or bog down the whole way thru the pawerband??
    what max rpm's are you turning?
    what color are plugs after you run the ski for a few minutes?? oily black or light brown, or light grey??
    does it idle ok??
    primer kit, hesitates, then takes off very good powerband. I think I am hiting rev limeter at top end. just got new tach need to test it out. plugs I think are white or tan new plugs only ran for 5 minutes. idles ok. thank you for the help
    Last edited by rlloyd; 03-17-2008 at 06:20 PM.

  4. #4
    96XPSS's Avatar
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    Quote Originally Posted by rlloyd View Post
    primer kit, hesitates, then takes off very good powerband. I think I am hiting rev limeter at top end. just got new tach need to test it out. plugs I think are white or tan new plugs only ran for 5 minutes. idles ok. thank you for the help
    Sounds like too much water in the pipe. Do you have a Jetworks flow valve in the stinger line of the pipe to keep the waterbox dry at idle?

    Excessive water will cause the exact symptoms you describe...especially with a aftermarket pipe.

  5. #5
    I installed a jet in stinger from lawn mower carb I drilled it just alitle so that a large grain of sand would not clog it up. the size is still very close to size that was recominded by r&d

  6. #6
    exhaust was the isue when I bought this boat it was burning up exhaust couplers I restricted water flow leaving the head to build water preasure in exhaust. it runs very cold now I can put my hands all over engine and exhaust and will not get burnt affter wot run. engine temp is runing less than 100 degrees I have a guage on it and it does work

  7. #7
    96XPSS's Avatar
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    U still haven't answered my question about the Jetworks flow valve...

  8. #8
    Quote Originally Posted by 96XPSS View Post
    U still haven't answered my question about the Jetworks flow valve...
    no jet works flow valve

  9. #9
    96XPSS's Avatar
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    Then that's your problem...

  10. #10
    96XPSS's Avatar
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    Quote Originally Posted by rlloyd View Post
    exhaust was the isue when I bought this boat it was burning up exhaust couplers I restricted water flow leaving the head to build water preasure in exhaust. it runs very cold now I can put my hands all over engine and exhaust and will not get burnt affter wot run. engine temp is runing less than 100 degrees I have a guage on it and it does work
    Do you have the stock water regulating valve on the waterbox? Burning up couplers is either clogged jets in the pipe or a bad water regulating valve. All SD's have a "pill" (restrictor orifice in the thru-hull fitting at the outlet) which does the job of providing correct water flow. What you've done is attempt to correct a problem incorrectly, and made another problem in the process. By overpressurizing the engine you now have too much water in the pipe, causing the bog.

    Don't believe me? Here's an easy way to find out.

    Remove what restrictions you installed. Remove the stinger line altogether and plug it, and the pipe stinger. Remove the WRV if it is on the waterbox and plug it. Make sure your midpipe jet is clean, and has good flow, then go make a quick pass not running wot but a few seconds. If your bog hasn't disappeared, then it is carburetion. You need a strainer installed between the pump and engine to keep your jets from clogging too.

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