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  1. #1
    Member
    Join Date
    Jun 2007
    Location
    Colona
    Posts
    51

    Yamaha 250 SHO Missing/Power issues

    Been awhile since i visiyed this site, and hopefully I can get some good info and a way forward. I'm having a continued issue in that when running WOT, after about 5-8 minutes, the motor starts cutting back, drops about 1100 RPM's and about 11 MPH. It holds at about 5000 RPM's and runs fine. This happens about every 30 hours or so. Its been into a local Yamaha repair shop, been look at, been put on the computer, been drove around but noone can seem to find the problem. When it happens, I change the plugs and it runs fine for about another 30 hours. This past weekend at a club tourney, it happened again, but this time like no other, it started missing while trying to get up on pad. This has never happened. Any good ideas would help.

  2. Member
    Join Date
    Mar 2005
    Location
    Montgomery, TX 77356
    Posts
    2,480
    #2
    There is another post from a guy with a 200 with similar issues. Most responses focus on fuel. The service manual notes three things that result in a reduction in speed. The ETV (Electronic Throttle Valve) is determined to be locked in the open position; Over revving ( > 6200 rpm); Knock sensor control which retards the timing,

    Good Luck and please return with the remedy if you find it.

  3. Member
    Join Date
    Mar 2005
    Location
    Montgomery, TX 77356
    Posts
    2,480
    #3

  4. Member
    Join Date
    Jun 2007
    Location
    Colona
    Posts
    51
    #4
    Thank you. I'll let you know what i finally find to fix this issue!

  5. Member
    Join Date
    Apr 2012
    Location
    Buffalo,NY
    Posts
    78
    #5
    Yes, please let me know what you find out.

  6. Member
    Join Date
    Jul 2017
    Location
    Georgia
    Posts
    137
    #6
    Same thing is happening to me.

    Edit - 2016 225 Sho with 10" Atlas
    Last edited by 4stroke; 09-30-2019 at 06:11 AM.