Thermostat

Discussion in '1st & 2nd Generation 1983-1989' started by Captain750f, Oct 23, 2017.

  1. Captain750f

    Captain750f New Member

    Country:
    United States
    Joined:
    Jul 12, 2017
    Messages:
    35
    Likes Received:
    3
    Trophy Points:
    8
    Location:
    Medina, OH
    Map
    Just got my 86 VFR750 running and driving . It had been sitting for several years and not taken care
    by the previous owner. It has new coolant in it, however the temp gauge seems really slow to react. After
    20 minutes or so of riding,the temp needle hasn't moved very much. Do these motors take that long to get warm or do I have a bad thermostat?
     
  2. OOTV

    OOTV Member

    Joined:
    Aug 20, 2011
    Messages:
    6,028
    Likes Received:
    662
    Trophy Points:
    143
    Location:
    Anaheim, Ca.
    20 minutes seems way too long for the motor to warm up, at least compared to newer VFRs (5/6 Gens), it’s really a matter of a few minutes before they’re warmed up. The amount of effort it takes to remove and test one on the 5/6 Gens is more time consuming and seems easier to just replace it than going through the troubles of the testing procedure. Not sure about your model year thermostat placement, but if it was me, I’d just go ahead and replace it, particularly if getting to the thermostat is as time consuming as the 5/6 Gens.
     
  3. Captain750f

    Captain750f New Member

    Country:
    United States
    Joined:
    Jul 12, 2017
    Messages:
    35
    Likes Received:
    3
    Trophy Points:
    8
    Location:
    Medina, OH
    Map
    It doesn't seem to be overheating or anything, no smell or excessive heat. I think I will just keep the trips
    short until spring. I wanted to replace the o-ring and seals in the water pump anyway, so I will just replace
    everything at once. Should I replace the temp sensor as well? I don't any of this stuff is real expensive.
     
  4. OOTV

    OOTV Member

    Joined:
    Aug 20, 2011
    Messages:
    6,028
    Likes Received:
    662
    Trophy Points:
    143
    Location:
    Anaheim, Ca.
    Based on the year of the bike and the reported condition of sitting a while, it might be prudent to change the sensor just so everything is fresh and new. I don't see an issue with waiting, since you know what the status is.
     
  5. Captain750f

    Captain750f New Member

    Country:
    United States
    Joined:
    Jul 12, 2017
    Messages:
    35
    Likes Received:
    3
    Trophy Points:
    8
    Location:
    Medina, OH
    Map
    Thanks for the input. I can keep the rides short, the snow in going to fly here in Ohio pretty soon anyway. I am going to change
    the fan switch in radiator as well, I'm not positive in works. I imagine if it didn't, the motor would have gotten hot very quickly.
     
  6. wpbarlow

    wpbarlow New Member

    Country:
    United States
    Joined:
    Aug 26, 2017
    Messages:
    40
    Likes Received:
    10
    Trophy Points:
    8
    Location:
    Central New Jersey
    Map
    Are you sure a thermostat is installed?

    Walter
     
  7. Diving Pete

    Diving Pete Insider

    Country:
    United Kingdom
    Joined:
    Mar 25, 2016
    Messages:
    923
    Likes Received:
    262
    Trophy Points:
    93
    Location:
    London
    Map
    I wouldn’t bother with changing the sensor - just check it works. Turn on engine, go for a ride, get back aand leave engine running until the fan kicks in. Should only take a couple on mins after a ride.

    Btw, IF THE ENGINE TEMP GUAGE SHOWS 230+ WITHOUT THE FAN KICKING IN then turn off engine immediately........
     
  8. Captain750f

    Captain750f New Member

    Country:
    United States
    Joined:
    Jul 12, 2017
    Messages:
    35
    Likes Received:
    3
    Trophy Points:
    8
    Location:
    Medina, OH
    Map
    Never considered that there maybe no thermostat. I guess that would explain a few things. I take it the temp sensor
    controls the gauge and the switch in the radiator controls the fan? Do I have that right? The temp sensor relatively expensive, and I would prefer not to replace it if I don't have to.
     
  9. Diving Pete

    Diving Pete Insider

    Country:
    United Kingdom
    Joined:
    Mar 25, 2016
    Messages:
    923
    Likes Received:
    262
    Trophy Points:
    93
    Location:
    London
    Map
    yep...

    It is also possible that the thermostat is stuck open.

    Even so test that the fan comes on...
     
  10. Captain750f

    Captain750f New Member

    Country:
    United States
    Joined:
    Jul 12, 2017
    Messages:
    35
    Likes Received:
    3
    Trophy Points:
    8
    Location:
    Medina, OH
    Map
    Thanks, I guess it's coming apart. While we are the subject of broken stuff. What controls the tach. It doesn't work either. I appreciate all the advise.
     
Related Topics

Share This Page