[DaveF]

Bob, on the old forum you started a thread about a 650 fan switch replacement, the Kemparts RF3. Have you been satisfied with its performance? Does it still appear to be an exact replacement?



RockAuto is now selling the RF3 as a wholesaler closeout for US $13.

 

[Sidecar Bob]

Wow, the things you find with the search function. Sorry I didn't reply to this when you asked, but better late than never, I guess

As far as I can tell, the switch is still working as intended. The 650 was on the road until the end of July last summer because I was painting the 'Wing and procrastinated a lot. The fan seemed to come on when it should and shut off when it should and the engine temp was more or less what I expected it should be.



This fall, I replaced the instrument panel I made - based on new(er) used Honda speedo & tach - tach failed and electronic replacement I mounted in its shell also failed - with a brand new completely electronic instrument panel that required a change back to the original temp sensor. IIRC, the fan came on a couple of times back in October, but I would be very surprised if it came on after that - this is the winter bike and keeping the engine warmed up is a bigger concern than keeping it from overheating most of the time. The temp gauge shows "bars" (typically 3 or 4 on a "warm" day - I think maybe the fan came on at about 5) so I can't tell if the switch is still coming on at the same temperature as it did in May 2010 (see the old forum thread you linked to), but I have no reason to believe it has changed.



BTW: You asked about this on 30 November 2010. At that time, the bike had only been back on the road for 17 days after 5 months of non-use while the GoldWing was on the road. By then it would have been cool enough out that the fan probably wouldn't have been on very much, so the data from March probably would have been the best I could have given you at the time.

 

[DaveF]

Thanks for the reply, Bob. I see you discovered the related thread.



The query has been somewhat overtaken by events. I purchased an RF3, and from all I can tell it's exactly like the original.



My preference is for a somewhat cooler operating range than the original so I intend to also try one of the cooler ones on the list.

 

[Sidecar Bob]

Remember that the optimum temperature range for a gasoline powered internal combustion engine is fairly narrow. When an engine runs outside the optimum range it uses more fuel to produce less power.

 

[DaveF]

Agreed. More info here.

 

[Pat Montgomery]

FWIW I just finished installing a Borg Warner version of this switch (ordered at Advance) into the CX650 and during testing the temp rose to just over half, fan kicked on and dropped temp to first "leg" on guage and cycled off. This was a great post and saved me money and time, thanks for bringing it back up.

 

[DaveF]

Thank you for the feedback.



I have not purchased the Echlin switch yet but would be perfectly happy to use one from Borg Warner. What was its approximate cost from Advance?

 

[David Fuglestad]

DaveF and Pappy,



Murray had suggested using a relay in the other thread. I clicked on the link for the relay, but the part was not found.



What relay did you use (if any)? On which wire does the relay get installed?



Thank you.

 

[DaveF]

Here are a couple of PRELIMINARY wiring diagrams for the electric fan and relay conversions I'm working on now. Some changes are to be expected during installation as the kinks get worked out.



My intention is to put together a detailed writeup on my web site when the installations are finished. In the meantime, this information may be of some use to you now.



Here is the relay selected for my own use. Others will certainly work fine, although I think it is worthwhile to select one with a resistor across the coil or else add your own resistor. The relay is physically located under the seat.



The diode is a good idea but not essential. It will help prevent large voltage transients. Its part number is TBD.



The manual fan switch is located either on the handlebars or someplace on the fairing. It can be used to force the fan to come on. It may be eliminated if the lower temperature fan switches prove to work out well.



For the GL500, the fused switched accessory power feed is from the spare accessory power connector located under the seat. Not all GL500's have this connector, but my bike does. The frame ground connection point is the one located under the seat - another ring terminal is added here.



P1 and P5 are both located under the fuel tank, just in front of the carbs. P1 is the right side and P5 is on the left side.

Hope you find this preliminary information helpful.

 

[Pat Montgomery]

Dave, switch from Advance was 19.99 + tax. I went with Borg because of my personal past use of their products, Echlin has always been good as well. I did have to order it in as the one they usually sell did not look exactly like the one I was replacing, looked like a cheaper China version.

 

[Sidecar Bob]

If you really feel you need a relay, you can use any standard automotive relay like you would use for lighting or a horn. They are available at any auto parts place.



But I have had the RF3 in my bike since Oct. 09 with no relay and it has not given me any problems yet. Admittedly, most of this bike's use is in the part of the year when keeping it warm enough is more of a concern than keeping it cool enough so the fan often stays off for weeks on end, but it was on for a substantial part of the summer both years, until the beginning of June in '10 and the end of July in '11, so the fan has cycled lots of times.



Re lower temperatures: As I have said before, if the engine is not allowed to come up to its optimum operating temperature, it will burn more fuel and produce less power.



If you don't believe me, read this: http://hea.ump.edu.my/images/mech/53.pdf (or at least skip to the bottom and read the conclusion), and if you want a demonstration of reduced power in an overcooled engine, try removing the thermostat and see what happens.



This is one of the major factors that contribute to the 650 producing 30% more power than the 500 while consuming about the same amount of fuel. Not only does the mechanical fan use power to turn it all of the time (as opposed to the electrical fan only using power when it is needed), but it cools the rad all the time too. Except in extremely hot conditions (they have to design for worst case expectations), the 500 never gets the chance to achieve optimum temperature.

 

[DaveF]

If you really feel you need a relay, ...



Yes, I do.

I've experienced a 650 ignition switch failure and have disassembled several others that showed evidence of overheating and arcing. In contrast, the 500 ignition switches rarely seem to fail. The single major difference is the routing of the electric fan power through the ignition switch. Wiring in a relay is a simple and effective fix.



Re lower temperatures: As I have said before, if the engine is not allowed to come up to its optimum operating temperature, it will burn more fuel and produce less power.



We are in complete agreement.



Regulation of the engine coolant temperature should be controlled by the thermostat. If a higher engine coolant temperature is needed then a higher temperature thermostat should be used.

 

[Sidecar Bob]

Regulation of the engine coolant temperature should be controlled by the thermostat. If a higher engine coolant temperature is needed then a higher temperature thermostat should be used.

The thermostat can only control the temperature at which coolant starts to be pumped through the radiator instead of running through the bypass hose. If the coolant coming from the rad is too cool the engine temperature will drop too much when the thermostat opens, regardless of thermostat value.



Back in the days when vehicles were expected to have a "tune-up" every couple of months, it was common to install a "winter thermostat" that opened a few degrees hotter than the normal one so that when the cool than optimum coolant from the rad met the slightly warmer than normal coolant in the engine the resulting mixture was closer to optimum. By making the fan turn on at a lower temperature you will cause exactly the situation that the winter thermostat was supposed to help deal with.



But its your money (wasted fuel) and your reduced horsepower, so do whatever you want.



I will stick with the proper temperatures for my bikes - with sidecars, the mileage is already bad enough and I can use every scrap of power I can get

 

[David Fuglestad]

FWIW I just finished installing a Borg Warner version of this switch (ordered at Advance) into the CX650 and during testing the temp rose to just over half, fan kicked on and dropped temp to first "leg" on guage and cycled off.

Pappy,



I'm trying to make sense of this thread and decide if I want to change my switch. I don't want to be the guy that fixes something until it is broken. That being said, if I can help my bike by managing the temp so that it runs at optimal temperature more of the time then I want to make this change.



Would you mind clearing these things up for me about your post?



1) Can the the Borg Warner be installed without any modifications? Same connectors, same size, etc? Does it come with a proper O-ring?



2) You posted that the fan kicked on about half way up the entire gauge. I want to make sure that you didn't mean that it kicked on about half way up the thick white bar on the right side of the gauge. That would be about the same as the stock switch. Were you saying that it was half of the total needle range?



3) You also wrote that the fan kicked off "to first "leg" on guage and cycled off". Do you mean it was just inside the thick bar when it turned off, or was it down in the thin white bar?



My concern is that the fan will not kick off on my bike on the way down, or be fighting the normal optimal heat range (to Bob's point) because both of my GL's (500 and currently my 650) would run just inside the thick bar when they are warmed up and cruising down the road with ambient temps between approx. 50 - 85 degrees. This seems like where the bike is supposed to run.



My bike is working with a new stock switch that was installed this past season. I don't want to fix something that isn't broken, and to Bob's point I want to make sure the bike runs hot enough for optimal combustion without running so hot that it will fry other things.



Maybe I shouldn't be arguing with Mother Honda.... since my bike is working as designed. It just seems like that gauge gets so high before the fan kicks on the way Honda designed it. Maybe I should just chill and accept it.....



Dave Fuglestad

 

[Ziturf]

A quick question. I'm in the midst of coverting my CX500 to an E fan. What is the reason for the resister on the relay and the diode on the fan circuit. Thanks Kevin

 

[DaveF]

What is the reason for the resister on the relay and the diode on the fan circuit.



These provide protection from high voltage transients that result when current is abruptly interrupted in an inductor, specifically the relay coil and fan motor.



The snubber diode is for the fan motor.



The resistor is for the relay coil, see here. As described in the article, it is important for the current in the relay coil to decrease rapidly so the contacts can open quickly and not "tack weld."

 

[DaveF]

I understand the point regarding coolant temperature in the radiator but don't believe it's a significant factor with a properly operating thermostat.



Both the 500's and the 650's register at approximately the same point on the temperature gauge at highway speeds. The measured temperature is being held relatively constant by the thermostat - in this situation the 650's fan is not operating at all. Hopefully the Honda engineers ensured the engine is operating at its optimum temperature in this case, since cruising down the road is the bike's normal operating mode.



It's only when there is insufficient airflow that the 650's temperature rises, and finally the fan cuts on.



It would be interesting to instrument the cooling system with thermocouples to see what the coolant temperatures actually are at various locations inside the engine, with both standard and lower temperature radiator switches.



Lacking something like that to provide hard data, nobody really knows for sure if it is an issue.



My opinion, and it is just an opinion, is that it's not an issue.

 

[Ziturf]

DaveF, Thanks for the info. K