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  1. #1

    Question RPMs increase when turning right - why?

    I'm still working on getting my RPMs back up where they should be after bringing my Raider (1996 700) back from the dead. Yesterday I had some very smooth water, so I was able to cruise along and just listen to the engine. When I go WOT straight ahead, still getting no more RPMs after about 3/4 throttle (just doesn't increase any more). But when I turn slightly to the right, the RPMs go right up where I think they should be at WOT (based on what the ski sounded/performed like new). It even maintains better RPMs in a hard right than it does going straight ahead.

    Am I possibly looking at some kind of throttle cable problem or is this just a product of the direction the impeller is rotating? It doesn't make sense to me - I mean just a slight move of the handle bars to the right, and you can hear it immediately jump in RPMs.

    Any suggestions to investigate how to get this increase when going straight ahead would be appreciated.


  2. #2

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    I have always had the same thing happen with my 2000 XLL and 2002 GPR. Someone a few years back explained to me that the rotation of the impellar makes the pump more efficient when you are in a right hand turn. I have always made my best RPM in a slight right hand turn.

  3. #3
    Moderator DrewNJ's Avatar
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    The 700 motors are known for this. Your lean... Fatten up your highs a bit and see if it goes away. If not you may need to drop your popoff a bit. I had the exact same problem years ago with an old waveventure.

  4. #4
    Stop staring at my tits NJJer's Avatar
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    R, I would check the throttle cable first. You may be on to something.

  5. #5

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    But the increase in RPM in a right hand turn does not explain why you aren't getting any more speed from 3/4 to full throttle. I am only talking about a 20-30 increase in RPM.

  6. #6
    Moderator DrewNJ's Avatar
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    It has to do with how the carbs are mounted. and how the diaphrams are situated. They are turned 90 degrees compared to the carbs on lets say a gpr. The diaphrams on a gpr are front to back. The diaphrams on the 701 is right to left. There was actually an aftermarket plate that allowed the carbs to be installed facing front to back...They go a bit lean typically turning left and go rich when turning right. It was known as the "left lean syndrome" and I think the info is in the Mikuni tuning manual if I remember correctly..

    Not saying I'm 100% sure it's the problem...just something to take a 2nd look at to be sure. Easy enough to fatten up the highs 1/4 to 1/2 turn and take it for a spin and see how it goes...
    Good Luck
    Doug

  7. #7
    Thanks to all for the feedback. I think the first thing I'll check is the throttle cable (easiest), but since this loss in top-end RPMs started when I put on the new impeller, the rotation issue makes some sense (I had decided it was just coincidence). It is a stock impeller, but not from this ski - it's from a 1995 Raider.

    Just to be clear, this is a single carb setup - I don't know if that changes anything.

  8. #8
    Quote Originally Posted by RichGPR View Post
    But the increase in RPM in a right hand turn does not explain why you aren't getting any more speed from 3/4 to full throttle. I am only talking about a 20-30 increase in RPM.
    It's not a huge increase from what I can tell - again I'm just listening to pitch and feeling the increase in speed, maybe 2 mph. I don't have any kind of equipment to get an exact reading.

  9. #9
    Is it almost winter yet??? ProXR 440's Avatar
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    Could possibly be the steering nozzle alignment also. The nozzle should want to center itself if you don't put any pressure on the bars, just hold on loosely, when the nozzle is turned it creates resistance in the water flow and loads the motor more dropping rpms. You can also check your neutral trim setting the same way by pulling in on the trim trigger when you are at top speed and see where it wants to self center at.

  10. #10
    Quote Originally Posted by ProXR 440 View Post
    Could possibly be the steering nozzle alignment also. The nozzle should want to center itself if you don't put any pressure on the bars, just hold on loosely, when the nozzle is turned it creates resistance in the water flow and loads the motor more dropping rpms. You can also check your neutral trim setting the same way by pulling in on the trim trigger when you are at top speed and see where it wants to self center at.
    That all makes sense, but if I have a trim trigger on this thing I don't know about it! It could very well be off center - the nut was loose at one point after I got thru riding, so I'll check that asap also.

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