Results 1 to 10 of 10
  1. #1

    Problem Yamaha GP 800

    Good day everybody
    After cleaning up the my Jet (Yamahe GP800) I trailed into the water. After warming up the engine, I rev up the Jet. Rpm went normally high, but the speed has not been reached. Only 30mph were Topspeed although the Rpm was normal as usual. What could be the reason? Impeller is normal and is not damaged or clogged. Does ne idea? Compression perhaps?
    At idle the engine doesn`t run very nice and has some misfiring. Also at full throttle are some misfiring.
    Has anyone some ideas?
    Sincerely Jannik

    Sorry for my bad english, because i`m form Germany and try it to translate in german with Google Translate

  2. #2

    Join Date
    Jul 2010
    Check spark plug?

  3. #3
    Quote Originally Posted by birdgod View Post
    Check spark plug?
    Thank you with that idea. I will Check this at the weekend.
    If the spark plug works normal. Any other ideas?
    Greets Jannik

  4. #4

    Join Date
    Jun 2015
    Kingfisher, OK
    Check compression

  5. #5
    Quote Originally Posted by txredxj View Post
    Check compression
    If the compression ist`t normal the rpm also should`t be normal, or?

  6. #6
    Prism's Avatar
    Join Date
    May 2007
    "New" Jersey
    I agree. Sparkplus or ignition wires. The misfire is the most likely cause of the low speed.

  7. #7
    04gtxsc's Avatar
    Join Date
    Mar 2006
    How old is the fuel?

  8. #8
    Quote Originally Posted by 04gtxsc View Post
    How old is the fuel?
    The fuel isn't old. I tanked up the Jet the day before at a normal gas stadion. And the fuel was empty before I tanked up. So there was`t old gas in the tank anymore.
    Last edited by Jajobe; 08-07-2015 at 03:50 AM.

  9. #9
    Running on one cylinder, either plug wire, or.............bad news

  10. #10
    I found my problem.
    It was the spark plug. Both spark plugs were damaged.
    Now with new pair of them the jet runs fantastic
    Thank you for your help

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. 2001 yamaha gp 800 ypvs servo motor
    By charliebizz98 in forum Yamaha PWC Performance (2-stroke)
    Replies: 7
    Last Post: 07-06-2012, 09:27 PM
  2. WTB Wanted Yamaha GP 800 and 1200 PV cyclinders in good condition
    By blasterboy1980 in forum Yamaha Classifieds
    Replies: 0
    Last Post: 08-18-2011, 09:00 AM
  3. Yamaha GP 800 top end rebuild questions
    By koryk in forum Yamaha How To & FAQs
    Replies: 2
    Last Post: 05-21-2010, 10:19 PM
  4. 99 Yamaha GP 800
    By dawull in forum Yamaha 2 Stroke Skis
    Replies: 1
    Last Post: 07-16-2008, 03:34 PM
  5. 99 Yamaha GP 800
    By dawull in forum Yamaha Classifieds
    Replies: 1
    Last Post: 07-16-2008, 03:34 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