Results 1 to 6 of 6
  1. #1

    Join Date
    Jul 2009
    Location
    on nc va border
    Posts
    75
    +1
    1

    '89 650sx starts but won't stay running, then backfires!!

    Well that pretty much says it all. The ski is completely stock mechanically except for a Dale's Bad Attitude Cdi , crankcase drain and oil pump removed and blocked off. The ski fires right up then dies. After starting several times, it backfires as loud as a beat up old farm truck. Fouled plugs, reed problem??? Thanks for the help.


  2. #2
    Quote Originally Posted by eazygoin View Post
    Fouled plugs, reed problem??? Thanks for the help.
    Are the plugs black and oily? if not, what color are they?

    Check for compression and spark in both cylinders and let me know what you find. Backfiring occured on my ski when one of the cylinders wasn't firing and the fuel was just going through it (the compression was too low, but that does not mean yours is having the same problem). Rule out the simple things first.

  3. #3

    Join Date
    Jul 2009
    Location
    on nc va border
    Posts
    75
    +1
    1
    yes they are black and oily. THANKS FOR THE GOOD ADVICE! I have a set of new plugs at my old house. I'll stop by and pick them up. Wish me luck.

  4. #4
    Usually black and oily means you are running rich or you need new plugs or you don't have enough compression to ignite the fuel (worn top end). If you have enough compression (at least 80 psi), try new plugs. If they get black fairly quickly, you may need to do some rejetting. You may be running rich.

    You can check to see if there is basic compression by puting your finger over the spark plug hole and cranking the engine over. It should pop your finger off if there is compression. Although this does not tell you if there is enough, it will tell you if it is weak or even there. Be sure to disconnect the spark plugs and move the wires away so you don't get knocked.

    You can check for spark by removing one of the plugs and laying the electrode over the hole on top of the head. Turn the engine over and you should be able to see a spark. Check all the cylinders. Again, be sure to disconnect the wires so you don't have it start up on you. Also, don't hold the wire while cranking it. Sometimes it can shock you. Just lay it there.

    Let me know what you find.

  5. #5

    Join Date
    Jul 2009
    Location
    on nc va border
    Posts
    75
    +1
    1
    Thanks for the advice. I will this weekend. I'm in the process of moving...........again!

  6. #6
    Flywheel may have spun on crankshaft a little. Throwing off timing.

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Replies: 7
    Last Post: 06-07-2012, 07:22 PM
  2. Waveblaster won't stay running
    By bassdocktor in forum Yamaha Old School Skis
    Replies: 8
    Last Post: 06-11-2010, 05:44 PM
  3. boat won't stay running
    By goBENGALS in forum Polaris Open Discussion
    Replies: 3
    Last Post: 05-24-2009, 11:41 PM
  4. 03 GTX SC won't stay running
    By INSMAN in forum Sea Doo Open Discussion
    Replies: 1
    Last Post: 08-14-2007, 03:07 PM
  5. 2000 SLX 1200 Won't Stay Running
    By 5001craig in forum Polaris Open Discussion
    Replies: 12
    Last Post: 07-17-2007, 01:51 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
  •