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Thread: Help! Yamaha YTM225

  1. #1
    Join Date
    Nov 2019
    Location
    North Carolina
    --
    3

    Help! Yamaha YTM225

    I have a 1985 YTM225DR and it is acting strange. I just bought it and it ran fine when I went and checked it out, now it’s running okay when it’s cold but as soon as it gets warm it doesn’t idle at all but will run like normal above 1/4 throttle. I have messed with the carb and set it back to 2 turns out along with cleaning. I have replaced the spark plug and flushed the gas tank. It has plenty of compression but needs valve seals as it smokes a bit. Does anyone know what it could be? Thanks

  2. #2
    Join Date
    Apr 2011
    Location
    Mexico
    --
    9,001
    Are you sure the choke is off when it gets warm?

  3. #3
    Join Date
    Nov 2019
    Location
    North Carolina
    --
    3
    Quote Originally Posted by El Camexican View Post
    Are you sure the choke is off when it gets warm?
    Yes, Choke is off.

  4. #4
    Join Date
    Apr 2011
    Location
    Mexico
    --
    9,001
    If you’ve removed the choke plunger and are certain everything is in order, then let me ask how much adjustment is left on the idle screw? Could it be as simple as that you need to turn it up?

    Poor running at low rpm is often a sign of a plugged pilot jet, but the choke circuit can add enough fuel to compensate for it to an extent.

    Is there a period of time between when you close the choke that it idles well before it stalls, or does it stall as soon as you close the choke?

    At the point that it doesn’t want to run without throttle have you tried opening the choke to see if it helps, or makes things worse?

    Is your float height correct? 15mm if I’m not mistaken, but don’t take my word for it.

    It sure sounds carburetor related. Don’t take this the wrong way, but there are people who consider removing the float blown and cleaning it out “cleaning the carb” when the really is that you must disassemble and clean all the jets and holes. Not knowing exactly what you’ve done it’s hard to guess what the problem might be, but all indications are that it’s related to the idle circuit of your carburetor.

  5. #5
    Join Date
    Nov 2019
    Location
    North Carolina
    --
    3
    Quote Originally Posted by El Camexican View Post
    If you’ve removed the choke plunger and are certain everything is in order, then let me ask how much adjustment is left on the idle screw? Could it be as simple as that you need to turn it up?

    Poor running at low rpm is often a sign of a plugged pilot jet, but the choke circuit can add enough fuel to compensate for it to an extent.

    Is there a period of time between when you close the choke that it idles well before it stalls, or does it stall as soon as you close the choke?

    At the point that it doesn’t want to run without throttle have you tried opening the choke to see if it helps, or makes things worse?

    Is your float height correct? 15mm if I’m not mistaken, but don’t take my word for it.

    It sure sounds carburetor related. Don’t take this the wrong way, but there are people who consider removing the float blown and cleaning it out “cleaning the carb” when the really is that you must disassemble and clean all the jets and holes. Not knowing exactly what you’ve done it’s hard to guess what the problem might be, but all indications are that it’s related to the idle circuit of your carburetor.
    Thanks so much for this response! I have stripped the carb down the carb body and cleaned all circuits. The choke plunged was removed and I removed all of the scores with 3m pad. The idle screw bearly has any adjustment left. I don’t have a service manual so I set the float to where it would just clear the pilot. I can try and set it to 15mm? It has to be carb. I ordered a cheap Chinese carb just to see if it helps. It has stock jets. There is a point if I ride it for 10 minutes where it idles really high then goes back to stalling. There is points where it seems to ride better with half choke but always bogs when given throttle. It would be easy if there was a constant problem but there’s so many different problems I can’t figure out what is going on.

  6. #6
    Join Date
    Apr 2011
    Location
    Mexico
    --
    9,001
    I’d skip the cheap Chinese carb and send yours to a guy on here that goes by Flyingw for a rebuild. It might cost more than the knockoff carb, but it will be worth it in the long run.

    As far as float setting, please lookup a how-to video. I will try to confirm the height this evening.

    Also, are you sure your throttle cable is in good shape and not binding at all?

  7. #7
    Join Date
    Apr 2011
    Location
    Mexico
    --
    9,001
    Here’s what the Clymer manual says.

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  8. #8
    Join Date
    Nov 2013
    Location
    Oxford CT, New Haven County
    --
    983
    When i bought mine it had an Ebay cheap chineese carb on it, it would start and run but if it stalled or I shut it off, that was it, it would NOT start again until it got cold again. (theres a post here someplace that tell all about it.) but I believe i replaced the main jet with the original one (the old owner gave me the original carb with the trike) and it ran fine after that.

  9. #9
    Join Date
    Nov 2013
    Location
    Oxford CT, New Haven County
    --
    983

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