03 VFR800 Thermostat Questions

Discussion in 'Mechanics Garage' started by JakeBoucher, Feb 14, 2017.

  1. JakeBoucher

    JakeBoucher New Member

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    Been having some cooling issues (I think) and just have a few questions. My service manual states the thermostat is fully open at 202°F. When I'm in traffic, in 35°F-60°F weather, the fan comes on at 225°F and its not hard for it to get in mid 230°F temperatures. I have always found an escape route to get some air flowing before I wait much longer, it's still uncommon to get in the low 200°F. I have a new OE thermostat and gasket waiting for installation, what else should I consider checking?
     
  2. GreginDenver

    GreginDenver New Member

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    I just finished up a refurbishment on a '99 VFR800 that I bought in mid December. When I took the radiators off the bike I found that they were covered in greasy road grime and the cooling fin areas where filled with tiny stones and other unidentified bits of debris. I figured that this coating of goo was probably not helping the radiators transfer heat away into the air, and the rocks and other bits of garbage weren't helping with airflow either.

    So I cleaned the radiators with degreaser and I used high pressure water to force out the rocks and debris. Just like you, I also replaced the thermostat. I've heard that when the VFR thermostat fails it simply gets stuck in a position (anywhere between full open and full closed) so you never know how the failure will affect your VFR.

    Also, if your bike is idling higher than the manufacturer's specification the bike will heat up more than normal at stoplights. Just an extra 100 RPM will do it.

    While you've gone to the trouble of getting into the "V" of the engine you should replace the O-rings for the water pipe connections to the front and rear cylinder heads. I also replaced the short little water pipes that go from the thermostat housing to the front and rear cylinder heads. If you look at my refurb thread you'll see just how bad these old parts looked, especially the old O-rings: http://vfrworld.com/forums/showthread.php/52488-Refurbishing-my-99-5th-Gen.
     
  3. JakeBoucher

    JakeBoucher New Member

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    I'll give my radiators a good cleaning just to be sure. My idle might be a few hundred RPM high, I'll drop that a bit.
     

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