Page 1 of 2 1 2 LastLast
Results 1 to 10 of 20
  1. #1

    98 GP800 Problems

    I bought a used '98 GP800 a couple of months back, and it has ran great since I bought it (completely stock). This past week, was on vacation and had it out. After a while out, on the way back in, WOT, it dies.

    I initially thought I was out of gas, turned it to the reserve line, tried firing it up a bunch of times in the middle of the lake with no luck. Towed it back to shore, filled it up and filled it up with gas (it only took 8 gallons of gas so I knew there was plenty left), tried firing it up again and it had problems starting. Finally got it to start but it ran like crap and it would only run w/ gas applied, once I took the gas off it would die again.

    Replaced the plugs on it since it didn't seem like it was getting a good spark, started up much easier, but still had the problem of running w/o gas and ran like crap (vibrated like heck).

    I'm going to take a closer look tonight, but was wondering if anyone knew what I should look at w/ the symptoms above. I have been pressing my luck w/o by not installing powervalve clips (I have them, but haven't gotten my gaskets in and the time to install them yet), I hope it's not a dropped powervalve.

  2. #2
    vomitspot's Avatar
    Join Date
    Apr 2006
    mobile alabama
    make sure your oil inj lines are hooked up!

  3. #3
    my fears are somewhat confirmed. fired it up today and there is some major clanking come from the front cylinder. did a compression check and the back checked out at 118, the front at about 30.

    i have no experience in repairing engines, i'm assuming I need to take apart the engine, look at the cylinder/pistons/crank shaft and go from there as far as what parts I need to order?

  4. #4
    Join Date
    Apr 2006
    Orange, TX
    Post pics of the carnage after you tear into it, and we can help.

  5. #5

    Join Date
    Dec 2005
    Beaufort, SC
    My buddy has the same ski. Power valve took out one cylinder the second summer he had it and we rebuilt it; replaced both pistons. Next summer the ring locator pin went on one of his OEM pistons and took out another cylinder. His ski is still in 4000 pieces (like mine).

    I'd put my money on the power valve.

    You can pull the cylinder with the engine still in the ski, just to see what caused your problem. But its soo much easier to rebuild it with the engine out.

    My buddy got lucky and never had to split the cases; just all top end work for him.

  6. #6
    cfgp927's Avatar
    Join Date
    Dec 2005
    Warsaw, Missouri
    If you need any parts.....I may have some. I know for sure I have a "0" hour head and a crank with less than 1.0hrs on it. Right now I don't have any cylinders. If you'd like to upgrade to an aftermarket head I have a very nice Pro-tec C2 w/35cc domes, also have some brand new 35cc domes cut for flat top pistons I'd sell with it.

  7. #7

    Finally, some pics!

    So it's been 8 months, and I've finally got the motor out of the hull, and partially taken apart. I took some pics, and need some help now. I apologize for the size of hte pictures, but I figured the bigger the better so you guys can actually see them, sorry if they are too big for some.

    First off, when taking the exhaust off the motor, i broke off one of the 8 bolts (they were in there with loctite so tight, I was using a pipe w/ my ratchet to get enough torque to get them off), not sure how to remove the bolt now since there isn't much to grab onto, and even if I could, the loctite I bet is not gonna let me vise grip it out, picture below, any ideas? I'm assuming just going with 7 is not ok?

    Now the pics of the cylinder and piston, the back ones look ok (I think), the front one is chewed up pretty bad, not sure what caused it, does this look like a PV issue? When rotating the PV's so they go in and out, it didn't look like the front was obstructing anything, but I also don't know what I'm looking for.

    Front Cylinder/Piston:


    Back Cylinder/Piston:


    I've never done any engine work before, I'm not a mechanic, I'm very handy in general though. Is this something that I can fix myself? How much damage was done? Should I leave this one up to the pros? Please help my sorry a** soul...
    Last edited by DTV; 04-22-2008 at 11:46 AM. Reason: Resize Pictures

  8. #8

    Join Date
    Aug 2007
    Rotterdam,NY & Moneta, VA
    to get that bolt out i ould drill it then use some heat and an easy out

  9. #9
    Quote Originally Posted by stingray152003 View Post
    to get that bolt out i ould drill it then use some heat and an easy out
    Thanks sting... here are some pictures down the front rod/crank...

    Someone was telling me (on another forum) that I need a complete motor rebuild, anyone here have any input?

  10. #10
    crashhard's Avatar
    Join Date
    Jul 2007
    Philly PA, Wildwood NJ, Indialantic FL
    where are you located?

Page 1 of 2 1 2 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. 98 gp800 problems!
    By countertop in forum Yamaha PWC Performance (2-stroke)
    Replies: 4
    Last Post: 04-23-2013, 09:50 PM
  2. 98 speedster problem
    By Harley30344 in forum Sea Doo Sport Boats
    Replies: 0
    Last Post: 06-17-2007, 08:02 PM
  3. Need carb rebuild kit for '98 GP800
    By qbzonk in forum Yamaha Open Discussion
    Replies: 3
    Last Post: 12-15-2006, 07:57 PM
  4. 98 gp800 impeller selection for max speed
    By spyder3000gtvr4 in forum Yamaha PWC Performance (2-stroke)
    Replies: 9
    Last Post: 09-10-2006, 05:51 PM
  5. Help rebuilding a 98 GP800
    By Jamie13 in forum Yamaha PWC Performance (2-stroke)
    Replies: 3
    Last Post: 02-19-2006, 02:11 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts