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  1. #1

    2004 fx140 (sparkplug gap and other Performance questions)

    Okay so my ski only seems to go like 43mph (gps speed) my friends waverunner goes like 52.

    I've changed my filter and plugs but I didn't gap them, could that cause a loss In speed?
    The rpms go up to normal now ( I think 8k?) but still not very fast...

    I've never had the propeller changed and hope I don't have to. Ski has 80 hours on it.

    Thanks!


  2. #2
    Yamaha Mechanic TunedFX140's Avatar
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    Does it have the correct spark plugs in it?? is there a bunch of gap between the wear ring and the impeller, I dont know if that ski has a L mode or not but is L mode on. My 2008 FX140 Cruiser is flickering 59-60 mph on the stock speedo no gps numbers but deffinatly faster than 43 mph. IIRC at wide open the rpms should be around the 10,000 mark.

    It could be possibly time for a new wear ring or impeller depending on how much sand has been sucked up through the pump. I have seen people beach one nd go to ride later and not even slide it off the beach a little ways before starting, they just fire it up andput it in reverse and gas on it rocking and cutting the bars back and forth. I have gotten to the point where i dont even try to help those type of people.

    Honestly though i have never gapped a set of plugs i just pop a fresh set of CR9EB's about every 100 hours or yearly whichever comes first.

  3. #3
    fx160's Avatar
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    you may need to change the air filter as well
    they can become cloged with oil and cause a loss in speed equal to your loss
    it's not always visible with the naked eye
    best way to check is remove the filter and go for a spin
    if performance is back to normal get a new filter
    if not put the old filter back in and keep looking

    kev

  4. #4
    Thanks for the replies guys.

    Tuned- It has the right spark plugs in it, How do i look at the wear ring? Would i be able to do that on a floating dock or would i need to put it on the trailer?
    It doesn't have L mode i don't think. I didn't think the rpm's ever went to the 10k mark, but they don't. they go to like 8k.
    I haven't ever changed the impeller and it's an 04...hmmmmm The impeller wouldn't keep it from reving to 10k rpms though would it?

    I put a riva(i think) high flow filter in it, but before i did that i rode without one to see if it fixed the problem. The ski revved only to 8k with it off, as well with the high-flow one on..

    Any thoughts guys?

  5. #5
    volltrex's Avatar
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    As the guys have said, you should be getting a shade over 10,000 rpm. Although the air filter does not sound like it is the problem, have you checked the oil level correctly? If excessively over filled it can foul a plug quickly.......it is also possible to have a bad new plug. Might be worth changing them again.......I always gap them, just to be sure.
    Failing that, then a compression check should be your next step.

  6. #6
    Quote Originally Posted by volltrex View Post
    As the guys have said, you should be getting a shade over 10,000 rpm. Although the air filter does not sound like it is the problem, have you checked the oil level correctly? If excessively over filled it can foul a plug quickly.......it is also possible to have a bad new plug. Might be worth changing them again.......I always gap them, just to be sure.
    Failing that, then a compression check should be your next step.
    I checked the oil level when it was hot and it was between the min and Max mark.
    I'll check the plugs again but right when I changed them they didn't let it go to 10k rpm

    How would I go about checking compression?

    Thanks

  7. #7
    volltrex's Avatar
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    Quote Originally Posted by yamahaa View Post

    How would I go about checking compression?

    Thanks
    You will need a compression test kit, or a gauge with 10mm thread connection. Not sure what the spec is for the FX.....but should be similar to the HO, which is 164 psi. Differance between cylinders should be no more then 14 psi. If compression is good then could be a fuel problem......clogged fuel filter (rare) injector filter screens may be partially blocked etc.
    Does the engine run smoothly through out the rev range?

  8. #8
    Quote Originally Posted by volltrex View Post
    You will need a compression test kit, or a gauge with 10mm thread connection. Not sure what the spec is for the FX.....but should be similar to the HO, which is 164 psi. Differance between cylinders should be no more then 14 psi. If compression is good then could be a fuel problem......clogged fuel filter (rare) injector filter screens may be partially blocked etc.
    Does the engine run smoothly through out the rev range?
    Hey volltrex, I'll see about getting a compression test kit. What should/can i do if it does come out to be low compression? The engine seems to run smoothly throughout the revs, so its weird. I would think that it would be ruff idle or something of that nature...but doesn't seem like anything at all

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