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Thread: yamaha 125 starts but dont run right

  1. #1
    Join Date
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    yamaha 125 starts but dont run right

    i bought this from a guy that stopped me on the road when i was riding on my 250r he asked if i wanted to buy a 175 for 50 bucks i get there to find out its a 125 he said it ran great before but not for 3 years so i cleaned the carb with carb and choke cleaner bought a new plug cleaned air filter checked compression which is perfect but will not start with rewind. when you pull it over it like rips your hand off, i broke 2 rewind ropes so i decided to push start it it started in like 6 inches if that but you can hold it wide open and it just stays at like 1/4 throttle. why is it doin these 2 things?? it also smoking more than usual
    P.S a day before this it auctaly ran great opened up and everything.
    any suggestions would be great thanks
    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

  2. #2
    Join Date
    Mar 2010
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    almost sounds like the timing changed.
    My guess is that since it ran great the other day.
    the spark advance plate may have stuck in the advanced position and wants
    to break ropes since it's firing with the piston on the way up....
    way too soon on the way up.

    You have a manual?
    free in the 'world class help' section.
    Recheck your timing. Should be easy.

    If it has cdi ignition, the advance curve is moderated by that but may also
    have a regular spring loaded advance plate under the points
    or pulse generator run off the cam.

    What else could it be?
    new crud from the tank getting into your nice clean carb?

  3. #3
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    its a 2-stroke so i didnt think it had all that stuff??? i though it all ran off the stator
    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
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    oops.

    Where DO they get spark from I wonder?
    Did you get a free manual in the world class help section?
    They seem different than the book I have.

    Generally, what could make those changes since it ran good and then changed it's mind dramatically
    ...poor running and
    killer pullstart rope resistance.?

    The only 2 strokes in my world are my chainsaws and little generator
    and for some reason, those are the only things that have not given me any trouble.

    Wish I knew.
    Surely someone will chime in.

    Please post what you find.
    I like to learn something new every day.

  5. #5
    Join Date
    May 2011
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    eden,ny
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    sounds like water in the fuel. although you said it ran fine the day before. did you happen to switch the petcock to res. In that time period? that would let pick up the water on the bottom of the tank.what size rope are you putting in the recoil? was in new rope or something you had laying around?

  6. #6
    Join Date
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    Water in the fuel x2.. but, did you actually clean your carb, or did you do like most and not take the jets out and clean them properly...

    I find a lot of people just dont know how to clean a carb.

    Also, what are you mixing your gas/oil at? More smoke = too rich...
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  7. #7
    Join Date
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    ok i totaly drained tank took air hose blew it out cleaned for dirt and such and put gas in a clear jug and let sit for a bit no water in it but a little iso-propohal (sorry for spelling) i took the carb completley apart used like half a can of carb and choke cleaner took the pet cock apart completly cleaned with carb cleaner and dissasembled and put back together. made sure all ports little crevaces everythine was clean. Jason125m i still have the oil injector hooked up and its at its lowest setting. air cleaner is clean i took it off and runs the same choke cable is not stuck. but it still ran exactly the same when i took the cable out of the carb?? same with air screw i turned it all the way in then took it out same... i tried diffrent carb that was on running 125 same thing 2... it doesnt pull over very hard but every id say 3rd pull it like pulls it back in and rips your arm off
    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

  8. #8
    Join Date
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    Avon, Minnesota
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    and ben i got a brand new 6 ft rope from a polaris dealer same thing thats on 500cc 4 wheelers EDIT and drjoe the killer pull start was like that 2 when it ran 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

  9. #9
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    Avon, Minnesota
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    and drjoe i couldnt find a manual for this trike i looked for a bit dont think there is one on here but thanks for helping so far everyone. also if this helps i was driving it down are road i went to the end then back up to my house i went around the house then it started to bog a little so i slowed down to 2nd gear then tried going up a small incline to our garage and it woulnt do it just wouldnt open up so i shut if off pushed it to the side on level ground started it by pushing it and never opened up since then... i have a parts trike so if anyone has suggestions mabey switch stators or sometin. just dont feel like doing it if its not that
    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

  10. #10
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    if it has good compression and your fairly sure its not fuel related I would go onto electrical one componant at a time

  11. #11
    Six Stroke's Avatar
    Six Stroke is offline At The Back Of The Pack Arm chair racerAt the back of the pack
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    You know, they could start an entirely separate forum just for these Yamaha 125/175 "not running right" threads.
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  12. #12
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    Quote Originally Posted by Six Stroke View Post
    You know, they could start an entirely separate forum just for these Yamaha 125/175 "not running right" threads.
    i have owned both the 125 and 175 the only trouble I ever had was water in the fuel on the 125(which ran just as the original poster explained) and the flywheel hub cracking on the 175. great,fun little machines IMO

  13. #13
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    Quote Originally Posted by yamaha driver View Post
    and drjoe i couldnt find a manual for this trike...
    There's "some" info for your machine here. http://www.3wheelerworld.com/showthr...5-Service-Data

  14. #14
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    ok thanks and not picking on six stroke but ive never had one this bad of shape looks like guy ran it and never maintaned it or just beat the s*&$ out of it. EDIT also trying to start it today when i pulled it over every 4th pull it like its a quiet backfire not load kinda like puhhh. and pumps out alot a smoke. im gonna pull of flywheel make sure that little pin aint sheared on the flywheel makin it off time
    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

  15. #15
    RID3R's Avatar
    RID3R is offline At The Back Of The Pack Arm chair racerAt the back of the pack
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    I would listen to whats been said... and also dont ride on the road.

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