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In stop & go traffic my bike runs hotter than I like, Not up to the red zone, but noticeably hotter, and I've never heard the fan come on. So this weekend I pulled the fairing and the radiator and checked the fan out. The fan worked when I jumper ed the temp switch, so I ran a wire for a bypass switch (manual fan control) and put it back together.



I've been curious about how the bike would handle without the fairing, so I took it for a ride naked. Didn't make that much difference, maybe I've gotten used to the fairing, anyway I put the fairing back on. But left off the radiator shroud and fairing lowers. I wanted to paint the shroud and the humidity was so high I didn't think painting was a good idea.



Took it out for a ride and found without the shroud & lowers the engine runs noticeably hotter. With everything in place the temp gauge would stay right at the skinny to fat change in the line, without the fairings it was about an eighth of an inch up. I was cooler, but the engine was hotter. Since I had the wire in place to manually turn on the fan I wasn't as worried about the temp and let it climb a little. The temp sensor did turn the fan on but the engine was hotter than I liked. And the fan turned off sooner than I liked.



Put the shroud and lowers back on and the engine temp is back to normal. Have to pick up a switch tomorrow for my manual fan wiring.



When I bought this bike I knew there would be some work involved. There has been, and it's been fun. This forum has provided a priceless source of information, and encouragement.
 

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The 650's are known to run hotter than the 500's.

this has to do with the electric fan not being on all the time.

it is normal for the 650 to wait until the gauge is just under the red zone to turn on the fan.

then the temp comes down to about straight down before it turns the fan back off.



but a manual switch is a good idea. just incase your thermo-switch fails.

mine did just last week.

but they can be bough from any parts store.

I think you get the one for a '82 honda civic.
 

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Besides the manual switch I would think that one could source a sending unit a few degrees cooler then what was installed by honda.
 

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My fan comes on at the "skinny/fat line" junction. You can hear the fan. You can feel the heat on your legs. If you cannot hear your fan I think something is wrong. My fan seems to drop the temp to about 2 needle widths back into the cooler "skinny" line area then turns off. Comes back on when it just enters the Fat line area. Most of the time when driving it never get up to the fat area. I have found myself in parking lots, driving slowly, once the fan turns off you suddenly have a much quieter bike without the fan noise.
 

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My fan comes on at the "skinny/fat line" junction. You can hear the fan. You can feel the heat on your legs. If you cannot hear your fan I think something is wrong. My fan seems to drop the temp to about 2 needle widths back into the cooler "skinny" line area then turns off. Comes back on when it just enters the Fat line area. Most of the time when driving it never get up to the fat area. I have found myself in parking lots, driving slowly, once the fan turns off you suddenly have a much quieter bike without the fan noise.




Maybe since you have a different bike than a gl650 there are different guts. But it has been noted that the fan on gl650's don't seem to turn on till right before the red.
 

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You can bypass the Honda switch if you so wished and fit a 75 Deg N/O(Normally open) temp sensor switch as per my electric fan conversions,



http://globalcxglvtwins.hostingdelivered.com/viewtopic.php?f=7&t=209



http://globalcxglvtwins.hostingdelivered.com/viewtopic.php?f=7&t=557



Shoreride on this forum as some and they don't cost a lot.



If I owned a CX650 this is the 1st modification I would do as I would want the bike/engine working exactly the same as my CX500s and cars whereby my fan kicks in just under the middle mark and out again just under the nominal mark in high temp/stopped situations.



At nominal both cylinders on both my CXs run at 85 Deg C/185 Deg F.
 

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Hi,

You are right about the fan cutting in late on the 650, I have a 650 euro motor in my 81 custom and found the gauge went much higher than I would have liked before the fan cut in, I too fitted a manual overide switch for heavy traffic situations. A replacement temp sender switch for the fan is about £58.00 ($100 ?) and makes no difference. The 650 rad is slimmer??? than the 500 models which may be to accomodate the quite bulky fan motor, I did think of fitting a 500 rad but the mounting brackets are different + the top hose outlet. I can bring my temp down a little amount at speeds of 60mph+ by switching the fan on manually which suggests I also have an airflow issue.

It may be worth trying a different temp sensor for the fan as Shep has used on his electric conversions.
 

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My fan comes on at the "skinny/fat line" junction. You can hear the fan. You can feel the heat on your legs. If you cannot hear your fan I think something is wrong. My fan seems to drop the temp to about 2 needle widths back into the cooler "skinny" line area then turns off. Comes back on when it just enters the Fat line area. Most of the time when driving it never get up to the fat area. I have found myself in parking lots, driving slowly, once the fan turns off you suddenly have a much quieter bike without the fan noise.


If it is coming on there either your guage or your switch is bad. The normal operating temp is in the broad white band about two needle widths.



Any lower than that and your bike won't be as efficient and will use more gas than an engine running at the proper temperature.
 
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