Normal operating temperatur in cold and hot

Discussion in '5th Generation 1998-2001' started by OnlyVfr, Nov 24, 2019.

  1. OnlyVfr

    OnlyVfr New Member

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    Hello,
    I just want to make sure if my temp readings are ok.
    In cold weather, on motorway, 140km/h engine temp shows 76-77C
    In warm weather on motorway, 140km/h about 100 (98-102)
    In traffic cold weather 80-98C
    In traffic warm weather 100+ max of 110 (fan on)

    Is 76-77 not too low in cold weather?
     
  2. Terry Smith

    Terry Smith Member

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    The thermostat opening temp is right around 76-78C so if there is plenty of cool airflow that is where the temperature will sit, regardless of engine revs. If anything I'd have said 100C on the motorway in warm weather was too hot, my bike usually sat around 80 on even really hot days, and only showed 100 if there was little/no airflow i.e. stopping in traffic. Sort of sounds like a stuck open thermostat to me but I could be wrong. If you put your hand on the radiator when you start then engine from cold, a good thermostat will hold the coolant in the engine block until it reached around 78C, then release this to the radiator, so the radiator should stay really cold for a few minutes then very quickly get too hot to touch. On the other hand, a stuck-open thermostat allows coolant through the radiators all the time, so the same cold engine test would show radiator temperatures slowly climbing from the time the engine was started.
     
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  3. Norse

    Norse New Member

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    Mine sits pretty stable at around 76-78 at motorway speeds, regardless of ambient temperature. In heavy city traffic on hot days, it will get to 103 and then start to drop as the fan kicks in.

    Remember that the temperature on the display is the coolant, measured in the radiator. Not the engine temperature.

    I had the thermostat replaced this spring. It was stuck open and the bike would struggle to even get to operating temperature in reasonably warm weather.
    A friend of mine had the opposite problem an his ST1100. The thermostat was stuck closed and the bike would get really hot, really fast.

    What you are describing could be a partially stuck closed thermostat. Not sure if they even can get stuck partially closed (I assume they can), but it not being able to fully open could explain your issue.
     
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  4. OnlyVfr

    OnlyVfr New Member

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    Thank you for all your replies. I will investigate it more when I get some time!:)
     
  5. James Bond

    James Bond Member

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    175 to 180 in the cold, 185 to 190 in summer, on any generation.
     
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  6. OnlyVfr

    OnlyVfr New Member

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    Motorway, traffic? Fahrenheit isn't it?
     
  7. James Bond

    James Bond Member

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    Fahrenheit, I'm American. Highway temps. If the fan is on, it came on at 221 degrees unless your bike is behaving incorrectly. Ride the bike.
     
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  8. VFRIRL

    VFRIRL New Member

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    Your running temp sounds fine, mine stays around 77 in all weathers except when in traffic it will climb up till the fan kicks in at 104,
    maybe your bike is low in coolant? you need to burp these vfr's when leaned over on the side stand to get all the air out.
     
  9. comradeQuestion

    comradeQuestion New Member

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    Yeah, those sound like normal temps to me. I ran my bike for quite some time with low coolant and got quite hot a few times (over 230° F). Now that I've serviced the whole cooling system, the bike sits at 170° F in cold weather and doesn't go up unless I'm stopped at a light. It will creep up to 217° F when idling before the fan comes on, then it cools down to 209° F pretty quickly and the fan stops. The hot weather was behind us by the time I got the bike put back together, but I think it should cool itself quite well now even in the summer.
     
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