Gen 4 Thermostat to replace or not to replace?

Discussion in 'Mechanics Garage' started by clintjennings, Jul 17, 2016.

  1. clintjennings

    clintjennings New Member

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    Hey all,

    I just got my first VFR a few months ago, a 97. I've noticed the temp doesn't come up on it unless its hot outside or I'm riding the piss out of it (which is often:smile:). It never overheats and the fans work properly when needed but I'm worried about wear and longevity of an engine that's always running cold. I've also read online that this may be normal for this bike but there is definitely no consensus as far as I can tell. Can anyone give me a straight answer as to if I should replace the thermostat or not? Or should I tape off part of the radiator as some have suggested?
     
  2. squirrelman

    squirrelman Member

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    you know it's running normaLLy if you're cruising along at 50 or 60 and the gauge is within the lower third, then shoots up to half-way or a bit above when you're at a long light or stopped in traffic. in 60-70 degree weather it takes about 15-20 minutes for the temp gauge to move if you're riding at moderate or slow speed.
     
  3. Terry Smith

    Terry Smith Member

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    My easy thermostat check is to keep your hand on the radiator when you start the bike from cold. If the radiator stays cold for a couple of minutes then quickly gets too hot to touch, your thermostat is A-OK. If the radiator slowly warms as soon as the bike is started, it is jammed open.

    Normal function is for the thermostat to stay closed until ~80C or about 1/4 on the gauge, which keeps coolant in/around the engine to warm quickly, and the radiator stays cold. Above that point the thermostat progressively opens, and allows coolant to flow through the radiator, so suddenly you have really hot coolant going through the radiator and you won't be able to touch it for long. Once the temp reaches 100C or 1/2 on the gauge, the radiator fan should switch on.
     
  4. Knight

    Knight New Member

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    Cadbury, with the bikes you have owned, have you ever seen thermostats get stuck in the closed position?
     
  5. Badbilly

    Badbilly Official VFRWorld Troll Of The Year!

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    248 pesos says that Cadbury has had bikes withoot thermostats and does not have Xray vision.
     
  6. Terry Smith

    Terry Smith Member

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    10 points and 248 pesos to Billy. Yes, I've owned a few air-cooled bikes in my time, and I'm still working on the x-ray vision, so far I've only managed to view radiation in the 390-700 nanometers range...

    I've pulled out the thermostats on my three Hondas. The VFR800 and ST1100 both had stuck open thermostats, the VTR1000's was perfect but I stupidly bought a new thermostat "just in case" because I was too dumb to externally diagnose that it was just fine and wanted to be left alone.
     
  7. Badbilly

    Badbilly Official VFRWorld Troll Of The Year!

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    What we need for stuff like that is a combination GPS and voltmeter. My bad on the Xray vision. I was led to believe it was OZtralians who had that.


    The OP should maybe take into consideration the relatively mild temperatures in the Portland, OR area. See "NOAA" weather..
     
  8. Gator

    Gator Insider

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    Cadbury why no thermostats? Even in mild climates a bike needs to get up to operating temp and a wide open system takes a long time to get there.
     
  9. Terry Smith

    Terry Smith Member

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    All my water-cooled bikes have properly functioning thermostats. I was responding to Knight's question regarding the position of stuck thermostats. My point was, I have examined three, and two of those were stuck open. And those were replaced with new items.
     
  10. Gator

    Gator Insider

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    Roger. Thought you would have them.
     
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