Beating a dead horse - thermostats and 5th gen operating temperture

Discussion in 'General VFR Discussions' started by garcenw, Jul 12, 2018.

  1. garcenw

    garcenw New Member

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    I’m likely beating a dead horse here, but I can’t find a true consensus on older postings. On cool days, say 75 F (22 C) or less, what does your 5th gen VFR coolant temperature gauge settle at once you reach steady cruising on the highway or interstate? With the temperature sensor in the front head, one would expect something a little above thermostat opening temperature. The issue is that our VFRs have the bypass circuit in the thermostat housing that always allows some flow to the radiators irrespective of thermostat state. That flow path deosn't seem insignificant in diameter. It’s hard to know how much cooling that accomplishes without applying some engineering rigor. I figure the best way is to ask the members what they are seeing.

    Probably the most useful responses would be those stating ambient temperature along with coolant temperature at that ambient temperature once you reach steady state while cruzing. Given the high failure rate of our thermostats, the highest confidence responses will be from those who recently replaced (say in the last few years?) their thermostats.

    I haven’t replaced my thermostat since I’ve purchased the bike (this March) and being the third owner, I don’t know the history of what has occurred regarding thermostat replacement. I suspect I’m in that grey area temperature-wise and suspect mine isn’t stuck, but doesn’t fully close (it reaches approximate thermostat temperature in ~3.5 miles of low traffic conditions on warm, say 80+ degree, days). Here are my steady state observations:

    Steady speed = ~45 mph, ambient temperature = 88 degrees F -> temperature gauge = 181 degrees F

    Steady Speed = 60 - 65 mph, ambient temperature = 73 degrees F -> temperature gauge = 165 degrees F

    Thanks.

    - Walt
     
    Last edited: Jul 12, 2018
  2. Lint

    Lint Member

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    I don't know my temps off hand, but I do know riding around with only the front upper fairing on drops temps considerably, even in 90°+ days here near Nashville, including all of the humidity, (if that even makes a difference to a radiator)
     
  3. GreginDenver

    GreginDenver New Member

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    My '99 5th Gen (with a new thermostat installed a year and a half ago) runs in the low 190s in those conditions (about 75 degrees outside, cruising on open roads).
     
  4. OZ VFR

    OZ VFR Insider

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    My 5G never gets below 77°C no matter how cold it is outside (never gets below 3°C here).
    On hot days, 36°C to 46°C, it sits around 86-88°C as long as I'm moving over 80kmh in clear air (no cars in front of me).
     
  5. dnbosiris

    dnbosiris New Member

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    I went out for a long ride on the weekend and it was approximately 7c ambient temp. My 5g sat at between 58 - 62c coolant temp doing 110 km/hr for about half an hour. I consider that to be a bit low! When the outside temp is closer to 20c then it will sit around 70 - 75c, rising in traffic.

    Sent from my SM-G950F using Tapatalk
     
  6. OZ VFR

    OZ VFR Insider

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    I think you need a new thermostat.
     
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  7. KizerSosay

    KizerSosay New Member

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    I'm close to you on my 5th gen.
    Steady 45mph on at about 185 F
    Steady 50+mph 174 F.

    Also, if it's hot out and I'm under 35mph it's hitting 210-220F. It cools better sitting still with the fan on in hot conditions. Not enough air flow to overtake the fan at low speeds.
     
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