Removed PV cover on gp800 and PV is missing, but engine runs great...??
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  1. #1
    PWCToday Newbie Shaun23a11en's Avatar
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    Removed PV cover on gp800 and PV is missing, but engine runs great...??

    Ok guys. 2000 yamaha gp800. Only has 53 hours. It runs great. Idles good, pulls hard. It would only hit 51 mph this past weekend and that's what the previous owner told me he could hit as well. I decided to pull the exhaust and do the wave eater clips upgrade. I get the exhaust off and the PV covers. The front cylinder is there and intact with the PV. As for the rear cylinder....the PV and pin are missing. I can see right down through the brass bushing. That piston is up in the bore. I pulled the plug and top of piston looks fine, no signs of damaged. As I use my mirror and shine a light down through where PV should be, I can see bottom of piston and there are signs of the PV hitting the piston skirt.

    My thoughts.....this engine runs great besides the fact that it's missing around 8 mph. Compression was tested before I took it apart and it's 135 each cylinder. I don't believe the PV could be chilling out in the crankcase and the engine still be running fine????

    What I'm leaning towards....the first owner put about 25 hours on the ski. I'm thinking he was running the engine and it locked up on him. He disassembles it like I have and notices the PV fell into the cylinder UNDER the piston. So, he pulls the PV out along with the pin and bolts everything back together and 30 hours later, here it sits, running fine on one PV only in the front cylinder. Could that missing PV actually be in the engine block, and the engine still be able to run without catastrophic failure? Or is my assumption of the previous owner pulling the PV out and not putting one back in correct???20160614_203003-1.jpg20160614_202951-1.jpg

  2. #2
    PWCToday Newbie Shaun23a11en's Avatar
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    Re: Removed PV cover on gp800 and PV is missing, but engine runs great...??

    since the compression is good, and the engine sounded fine im not sure what to do. pull the cylinders off, or buy a new powervalve and clips, install and go hit the water?

  3. #3
    Top Dog SkiSwede's Avatar
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    Re: Removed PV cover on gp800 and PV is missing, but engine runs great...??

    PV cannot fall into the crankcase. It went out the exhaust. Replace both PVs and go ride.

  4. #4
    PWCToday Newbie Shaun23a11en's Avatar
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    Re: Removed PV cover on gp800 and PV is missing, but engine runs great...??

    SkiSwede, since you say it went out the exhaust, does that mean im just extremely lucky the engine runs good and has good and even compression?

  5. #5
    PWCToday Newbie Shaun23a11en's Avatar
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    Re: Removed PV cover on gp800 and PV is missing, but engine runs great...??

    what about the damage the piston skirt is showing? since the compression is good, just run it?
    Last edited by Shaun23a11en; 06-15-2016 at 02:48 PM. Reason: spelling

  6. #6
    Top Dog SkiSwede's Avatar
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    Re: Removed PV cover on gp800 and PV is missing, but engine runs great...??

    Well I haven't seen the piston, but if compression is good I probably wouldn't worry about it.

    You are lucky, but not unusual. I've seen plenty of engines with missing powervalves with absolutely no signs of damage at all. Somehow they just shoot straight out the exhaust port when they break off.

  7. #7
    PWCToday Newbie Shaun23a11en's Avatar
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    Re: Removed PV cover on gp800 and PV is missing, but engine runs great...??

    Here's the piston. Would I be in trouble if I used this based on the condition that can be seen in the picture knowing that it did produce 135 pounds compression?20160615_154739.jpg

  8. #8
    PWCToday.com Is My Home Away From Home Grumpy Old Guy's Avatar
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    Re: Removed PV cover on gp800 and PV is missing, but engine runs great...??

    Thats where the PV was rubbing before it broke off.

    Just run it if you are trying to save some $,or fix it if you are nervous nelly

  9. #9
    PWCToday Newbie Shaun23a11en's Avatar
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    Re: Removed PV cover on gp800 and PV is missing, but engine runs great...??

    Here are the cylinders and pistons. Looks very good to me20160615_171156.jpg20160615_171454.jpg20160615_171534.jpg20160615_171522.jpg

  10. #10
    PWCToday.com Is My Home Away From Home don37725's Avatar
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    Re: Removed PV cover on gp800 and PV is missing, but engine runs great...??

    It's June 16th already - put that thing back together and go ride!

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