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Thread: Tri moto 125 weak spark?

  1. #1
    Trikeboss's Avatar
    Trikeboss is offline At The Back Of The Pack Arm chair racerFirst time rider
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    Feb 2011
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    Tri moto 125 weak spark?

    My tri moto I just picked up cheap will not even try and fire and wont start out of the blue...Got it from a friend for $100 - It has always ran ok a bit boggy down low and rich up top but ok thats why i got it to fix the low end bog and to get some more rpms out of her... then just died and would not fire..It sounds like the kill switch is on when im trying to start it-sounds like it has no spark?...New plug-I cleaned the carb.Compression @ 120lbs..no luck...I checked the spark and it looked a bit skinny and weak not sure if thats the problem or not...How can I test this? What should be my next step? I want to ride this beast!

    Last edited by Trikeboss; 12-13-2011 at 09:59 PM.
    1982 HONDA ATC 185s
    1982 HONDA ATC 110

  2. #2
    Join Date
    Jan 2003
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    Southern MN
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    A couple common problems on the YT's are sheared flywheel key (usually will jerk your arm back when trying to start though) or faulty ignition coil. The coils on these like to crack on the plastic body, and arc over to the frame. Try starting it with the fenders removed, and see if you can see spark jumping from the coil when you also have the spark plug grounded. If it looks ok, try unplugging the kill switch at the connector, then try to start. That rules out kill switch problem. Otherwise, try a little starting fluid down the plug hole, and see if it pops. If so, you have a fuel issue. I know if you need a new coil one from ALL the yamaha 3 wheelers from a 60 to 250 will work perfectly. Even the 4 stroke 200 and 225's will work. Hope I gave you an idea. ---- Jon.
    THE 80's RAGE! Currently owns:
    81, 85 Yamaha Tri Moto 125
    83 Yamaha Tri Moto 200 x2
    82,83 Yamaha Tri Moto 175 project
    85 Yamaha Tri Z 250
    84 Kawasaki Tecate 250
    84 Honda ATC 70
    85 Honda ATC 350X
    84 Honda ATC 250R
    (2) 84 Honda ATC 200x
    82, 83 Honda ATC 185s
    81 ATC 200
    Lots of other parts and bikes

  3. #3
    Join Date
    Jan 2011
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    Avon, Minnesota
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    its problay the coil. you can go to an autovalue and pic up a coil, its kinda a universal i have on on mine and works good.
    1983 honda 200x 185 motor, Uni air filter, bassani exhaust, itp rims. FOR SALE!!!
    1982 honda 200 bigred cobra exhaust

    1989 yamaha banshee fmf gold pipes boost bottle k&n airfilter

  4. #4
    Join Date
    Nov 2007
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    ulysses pa
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    1,231
    is the spark blue or orange? blue being good and orange being weak. what is you plug gap at? have you cleaned any connections? i always try this before i buy electrical parts. remember that electric parts arent returnable so if you buy and dont need its yours to keep. i would go through all connections first, pull them apart, spray some W-D down in the connection, work them in and out a couple times and reconnect. also clean the connection at any grounds. continually re-check for spark and if it doesnt get any better then start testing components. good luck!

  5. #5
    Trikeboss's Avatar
    Trikeboss is offline At The Back Of The Pack Arm chair racerFirst time rider
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    Well it fired with starting fluid....so the spark was good.... Im no expert but the more I read im thinking a crank seal went bad and is causing the fouling problem ...I sold it for cheap to someone who wanted to fix it up...I would have fixed it myself but im learning that im a honda guy when it comes to ATC's

    Sold the 125ytm and got a nice running 185s for cheap the very next day...Man I love putting want ad's on craigs list
    1982 HONDA ATC 185s
    1982 HONDA ATC 110

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