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  1. #1

    Default odd Kawa 750sx problem... where to start troubleshooting?

    I have a pair of 750sx's ('94). One I have spent the last few years doing right up, porting, pipe ..etc...
    The second one, the girlfriends gets the parts the first one outgrows as hand-me-downs. So it has a Coffman's pipe, advance, new Boysen reeds this year, new stock shaved head (170psi), and my old single OEM carb which I rebuilt. Now this ski has not had any internal work so was a little tired but I figured if I got a couple more seasons out of it, then GF would get my ski and I would start on an 800 down the road. Anyways, I put my carb on this one because I always had a very hard time tuning this ski and thought if I took my carb off mine, at least I know it works excellent and throw the other one away.
    Well this ski worked fine for about 2 days. Now what it does is idle very fast first of all at all times in the water. Sometimes when you are coming to shore (more often than not) you cannot shut the thing off if you hold down the stop, or repeatedly press it. It will always eventually shut down in a few seconds but its unnerving cruising into a beach and it not working. Prior to this lake trip it started/idled/stopped just fine in the garage. Now since I have returned from trip, have it on the trailer, I have started it to try and figure out what is going wrong.
    Out of water it will idle normally, then speed up quite fast, then go back to normal, then up to quite fast and repeat. The last time I started it on about the third increase in speed it all of a sudden opened almost wide open and was screaming and did not slow down. Of course I am pressing like mad on the stop button and it takes a couple seconds before it actually stops. It was newly out of the water when I did this (trying to spray out the pipe water) so no damage I am sure but I have not started it again since.

    So, my question is, where to start on this? My first thoughts would be fuel/carb but that doesn't account for the 'can't turn it off' thing, or maybe it does? Since this craft had carb problems before (not like this..just would run well, then later in day flood out and hard to start..etc) mayb it is something else.. I have new reeds, gaskets on intake/carb, and carb was rebuilt. Since ignition module does not control fuel, I think that is out although what else would cause the no stop situation? Could the advance plate cause something like this?

    I have ordered another carb rebuild kit but any other advice would greatly be appreciated.

  2. #2

    Default

    an air leak would cause the engine to 'run away' like you describe. maybe the carb gaskets aren't seated properly?

    if you choke it when the ski revs up, it should kill it.

  3. #3

    Default

    could be the throttle cable sticking too and not letting the butterflys close.

  4. #4

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    Its not the cable..that works fine. And can't use choke because I got a primer on it.

    I thought the primer might be the cause and carb was sucking gas through it but I watched a bubble in line and it didn't move. I will check gaskets. I thought a leak somewhere as well but not being able to shut it off is odd. I can see not being able to when it is out of water and screaming, but in the water you can be knealing on it at a very brisk idle so it is stable, and under load, and it still won't shut down immediately

  5. #5

    Default

    maybe check the start/stop wire connectors too make sure they are clean and in good working order. it does sound like an airleak. my sxi wouldn't rev up but sometimes i had to hold the red stop button for 2-3 seconds and then it would kill the motor, not sure why but that was the way it was.
    1996 SuperfrickenJet

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