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  1. #1

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    Too much prop causing detonation?

    Hey guys,

    Last week I installed my new 14/20 Dynafly in my stock 2006 1300R. I know the general consensus is that the stock motor has trouble turning this prop. I wanted to go get some RPM readings just to see what the baseline would be before adding mods to increase RPM. The results weren't very promising. I could not get it to turn more than 6400rpm at WOT. Also, the ski felt like an absolute slug. Now, my average RPM with the stock prop was 7160 before the install. I have read that the stock motor SHOULD turn the 14/20 about 6800-6850. I was nowhere near that. Well, I pulled the plugs this morning just to check compression to start finding out what the deal is. I noticed the plugs looked a lot different from before. I smelled hardly any fuel on them at all. Below are two pictures (the plugs were put in new right before I did some runs). I'm no expert but they look on the lean side to me. Could it be possible the prop loaded the motor so much to cause detonation? Could the prop be binding on the wear ring causing such a low RPM? Any input is greatly appreciated!





    Mike


  2. #2
    philip_gpr's Avatar
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    Did you remove the plugs on the water doing a plug chop?

    Or did you remove the plugs on land? (sounds like on land)

    The plugs will show you their state for the last rpm the motor was running.

    You might ttry putting the stock impeller back in and see if your RPMs return.

  3. #3

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    Quote Originally Posted by philip_gpr View Post
    You might ttry putting the stock impeller back in and see if your RPMs return.
    I just took the 14/20 off. The edges are all perfect and doesn't look there's any sign of binding or wear. At least if the RPMs return with the stock prop, that will rule out any gremlins internally. I just can't see my ski running so strong on the stock impeller (69.0 @ 7220rpm) and then losing so much just because I went to the 14/20.
    Last edited by Fusion; 06-17-2007 at 10:29 AM.

  4. #4
    philip_gpr's Avatar
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    "I just can't see my ski running so strong on the stock impeller (69.0 @ 7220rpm) and then losing so much just because I went to the 14/20."

    Agreed.

  5. #5
    African-American
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    isnt 13/19 recommended for a stock boat ?

    i know its a stupid question, are you sure you installed the shaft and impellor properly ?

  6. #6

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    Quote Originally Posted by spaceman View Post
    isnt 13/19 recommended for a stock boat ?

    i know its a stupid question, are you sure you installed the shaft and impellor properly ?
    Not a stupid question at all. I'm pretty sure I did, it doesn't look like it's very hard to screw up. The shaft and prop seemed to turn pretty freely with no signs of binding anywhere.

  7. #7

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    Quote Originally Posted by Fusion View Post
    the plugs were put in new right before I did some runs
    I have allways found that it takes a good hours running on new plugs before you get any sort of reasonable reading. Otherwise they just show the white of the porcelin and looks lean.

  8. #8
    ra1nmakr's Avatar
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    could there be a clog in the fuel sender? if you say that it really didnt smell of gas on the plugs and you are getting detonation; it sounds like lean pop. from my experience with cars and trucks is, in a case like that, the fuel pumps/injectors might have failed. not sure if it is the same with skis yet since i have only begun to learn and wrench.

  9. #9
    HIGHLAND LAKE BOYS's Avatar
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    you need a efi controler &remove cat

  10. #10
    just GOT TO DO IT! great lakes gpr 1200's Avatar
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    That's a lot of impeller to be turnning with a stock boat. I know My stock 1300r 04 with 18 hrs on it won't do IT! I have never ran a tack on my stocker. are those all the mods you have? Man you are kicking some a$$ to get that speed with those mods. My stocker only runs 59 Mph with a sealed pump and stock ride plate. maybe I got a crappy ski?

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