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  1. #1

    Having running issues with Yamaha 1100 waverunner...wont stay running and backfires..

    OK, here's the long and short of it.....

    I bought a 1996 Yamaha waverunner 1100 (wave venture) really cheap (I mean REALLY CHEAP!!!). Previous owner said that it would not crank or do anything.

    Found a wire that was not connected to battery power, connected it and it cranks and tries to start.

    Has sat around for over three years so, drained all the oil fuel (oil/gas premix), replaced the fuel filter, rebuilt the carbs (friend did these, might be part of problem) , new gaskets for carbs etc.

    Got the thing to start, if I start it with a spray of carb cleaner, it backfires upon start-up. Otherwise, runs really rough and almost sounds like its getting no fuel. Will back fire sometimes threw the carbs.

    I got the thing to kinda idle but runs really rough and will stall if left alone. Hard to start and if I feather the throttle, I can keep it running but it will back fire sometimes.

    Really want to use this ski especially since it cost me almost nothing.

    My main questions are this.....

    1) Could the running issue be just the fact that the carbs are not right? Getting plenty of fuel, pump works great.

    2) The backfire happens with 2+2 or if it tries to rev it up. Actually blew off the exhaust rubber hose at the muffler area!!!

    3) What spring rate should be in the carbs? Orignally the middle carb was 5 1/2 turns out on the mixture screw. Set them to factory specs, what should I use as spec for this?

    4) Ski has 134 hours on it. Could there be a timing issue that causes this on the 1100 or is the timing set by the stator like on the 700? REally not sure if fuel or timing issue (plugs gapped correctly and has good spark)

    5) Anything I should look for with this ski. I have two 700's and this thing is so much harder to work on!!!




  2. #2
    NO replies at all??? Really need some help here and can't see someone not having a similar issue. Please help!!!

  3. #3
    silvercrxsir's Avatar
    Join Date
    Sep 2011
    Honestly the best place to start is to do a compression test,leakdown test the engine,and rebuild the carbs (actually buy mikuni kits)and set everything to factory settings.most likely the internal carb prefilters and jets are clogged,especially since it sat for years with premix in it so I'm sure they are clogged.

  4. #4
    as posted in original post, rebuilt the carbs, did compresssion test, 120 psi each cylinder, all internal filters are cleaned and carbs were cleaned professionally. All that was posted was done, wondering if the reeds could be bad?


  5. #5
    Myself's Avatar
    Join Date
    May 2007
    North Central Arkansas
    Check the AC Voltage output from the lighting coil. I've had a couple Yamaha's do that and they both were only putting about 25-30v to the CDI. That's just not enough power to light up the ignition.

  6. #6

    Join Date
    Jul 2012
    Miami, Florida, United States
    you can check the reeds if that passes try richining your low and high speeds half a turn and test if still acting up you can check for a fuel restriction or your pop off pressure you might habe to big of a spring

  7. #7
    boudin's Avatar
    Join Date
    Oct 2009
    Houston, TX
    Did you check to be sure all three plugs have a good strong spark? Also possibly a sheered woodruff key caused the flywheel to slip, but you'll need to pull the engine to check.

    If it's been backfiring that much, you may have also blown out some reeds.


  8. #8
    GoFastGuru's Avatar
    Join Date
    Jul 2010
    guntersville Ala
    reed valves

  9. #9

    Join Date
    Feb 2010
    Tampa, Florida
    I agree that if it's backfiring, the reeds may not be in good shape. If you work your way down in the engine, you may want to consider checking/replacing seals and inspecting all other parts.

  10. #10

    Join Date
    Jun 2012
    McCalla, Alabama, United States
    Agree w/ everyone else on this... Pull the carbs, intake and check those reed valves first. Pressure test would be good as well because with it sitting up the crank seals may be brittle, sucking air and causing problems.

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