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  1. #1

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    Mar 2009
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    XL 800 power/RPM loss

    I have a 2001 XL800 that has always run perfectly. 7000 rpms and great throttle response across the entire rpm range.
    last week,after about a 10 mile cruise across the lake @ about 30mph, I noticed that it was down on power and max rpms have dropped to around 6000.
    Ran it around for a little while hoping that maybe it just needed clearing out but it didnt change. It still starts and idles fine.

    Pump was clear,no blockage. impeller looks nearly new with no damage or dings.
    fresh 89octane fuel (oil injection removed,50-1 premix)
    compression cold WOT @155-160 psi
    plugs are older and could stand to be replaced but were toasty brown not sooty or wet
    Power valve motor is cycling and the shaft is moving.
    pump bearings and grease look new and turn smooth. Not sure how to check the front bearing behind the motor though
    no new or unusual noises from the pump or motor

    I did notice that the impeller is rubbing on one side of the plastic liner. its cut into it and left a groove about .010-.015 deep.
    How do you align the motor to the pump? is it an"eyeball" alignment or is ther a reference point for a dial indicator?
    This ski has always had a slight cavitation issue when accelerating at full throttle out of the hole with a big rider. Part throttle it does fine. However since the RPM/ power loss it wont cavitate
    I apreciate any help ya'll can offer. I'm new to PWCs so please pardon my ignorance
    Thanks


  2. #2
    this sounds like an issue with the power valves. how long have you owned the craft? how many hours have you put on the craft? the power valve shaft can be moving (rotating) and the power valves not function correctly due to several common problems. 1) the pin has fallen out of the end of the power valve shaft and the lever can not move the valve up or down, 2) the screw thru the lever into the rotating shaft is broken or backed out not allowing the lever to move the power valve up or down, 3) the power valve blade is broken from the shaft and could still be in the cylinder or it has exited the cylinder thru the exhaust pipe (hopefully without doing to much damage). use a small LED light on the end of a flexable shaft that fits into the spark plug hole and look for damage to the tops of the pistons. dont freek out though, the valve can escape some times without causing damage, you could be lucky. if it was me, i would pull the head before running it anymore.

  3. #3

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    Quote Originally Posted by wavedude View Post
    this sounds like an issue with the power valves. how long have you owned the craft? how many hours have you put on the craft? the power valve shaft can be moving (rotating) and the power valves not function correctly due to several common problems. 1) the pin has fallen out of the end of the power valve shaft and the lever can not move the valve up or down, 2) the screw thru the lever into the rotating shaft is broken or backed out not allowing the lever to move the power valve up or down, 3) the power valve blade is broken from the shaft and could still be in the cylinder or it has exited the cylinder thru the exhaust pipe (hopefully without doing to much damage). use a small LED light on the end of a flexable shaft that fits into the spark plug hole and look for damage to the tops of the pistons. dont freek out though, the valve can escape some times without causing damage, you could be lucky. if it was me, i would pull the head before running it anymore.
    thanks for the reply
    have only owned it for about 6 months. bought a "matched pair" on a trailer and have run them pretty hard with zero issues since we bought them.
    Besides this I've been extremely happy with them
    I will pull the head and check it out and also take a closer look @ the pv shafts

  4. #4
    do you have any history from the previous owner??? did they disclose any repairs? have the power valves been upgraded etc??? the 01 model's power valves need to be replaced to the upgraded version... how many hours on the clock?

  5. #5

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    pulled the head
    bores are std size
    cylinders look good and powervalves are still there.
    BUT....found thin slivers of aluminum on the head on both cyls. not alot of them but they are obviously fresh and I cant imagine that this is normal.
    faces of guillotines are shiny as if they are making contact. shouldnt they stand off a little from the piston?
    the guillotines seem to be just floating in place. they dont lift when the servo motor cycles but I can push them up with my fingers. They are supposed to actually lift arent they?

  6. #6
    there you go,,,the metal must be from the piston edge of the power valves. yes the guillotines are suppose to move up & down with the servo movement. they must be broken from the shafts. go ahead and remove the exhaust system to access the power valves to remove them. if the cylinders are in good shape & the compression looked good per your first post, then maybe you can get away with just new power valves....get some pictures posted of the power valves, piston tops, cylinder walls & sides of each piston thru the exhaust ports.

  7. #7

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    heres some pics of my"2pc"power valves

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    Looks like I dodged a major bullet here
    you can see the slivers in the pics of the combustion chambers
    notice how shiny the guillotines are
    piston tops,combustion chambers and cylinder walls look good

    for the new PV's ware there any brands to avoid or are they all abot the same?

  8. #8
    did both PVs have the bushing/sleeve? you ony show one. are the cylinders sleeved? to tell if they are lower the pistons and look into the ports and look for a ridge or line that is not quite flush with the wall of the ports. post some pics of the cylinders. the PV levers are the updated type. did you find the hours on the engine? also see if you can get a pic of the pistons thru the exhaust port. you could have some potential damage to the rings, the ring lands on the piston or some damage to the piston itself. i think you may be in fair shape hear but need to proceed with caution... Oh yeah, forgot to ask,,,,do you have any knuckles left after removing those exhaust bolts???

  9. #9

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    I removed both bushing. All parts are present and accounted for just not in the pic.
    Cant get a clear pic thru the exhaust port fo some reason but the piston skirts look good. no scuffing and you can still see the tool marks
    rings are free in the grooves. when I rock the piston I can see that theyre not stuck. Dont see anything that looks bad on the ring O.D. Hoping the healthy compression numbers are a good sign.
    The cyls do have sleeves.I just assumed they were that way stock. Bores look good. no grooves and hone marks are visible but I'll mic them tomorrow.
    The ski has 182 hours on it but the motor was supposedly rebuilt or replaced at some point. There are lots of signs that its been opened up before.
    Knuckles are mostly scar tissue these days anyway,but yes,I did shed some blood...really wasnt as bad as I thought it would be but there was 1 bolt that took more time than everything else combined. I knew if I broke it I would be pulling the motror so I just had to work it real slow.
    Its obvious you know your way around these things. Really appreciate the advice.

  10. #10
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    The Jugs are not sleeved from factory. Someone has done a rebuild on the top end at some point

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