VF500 cooling issues/questions...

As some as you read in my introduction, I recently purchased an 85 VF500 Interceptor that has been dormant inside a guys house for 11 years. I have spent some time cleaning it up and paid a mechanic to remove/rebuilt/sync the carbs, and I have put it back where it belongs, on the road.

The patient appears to have a nice strong heartbeat and rides well. In the morning, the temperature gauge rises to the normal mid-way position and appears not to have any issue while the ambient air is 50 or so degrees. But when I ride later in the afternoon, I appear to have mild heat issues. With the outside air being in the 80s, when stopped at lights, the gauge goes 3/4 the way to hot before the fan comes on to maintain. It has not gone beyond the 3/4 spot, but its very concerning. I have checked the coolant level as well as ensuring the pressure cap is on tight and maintaining a seal. On Thursday I will replace all the unknown coolant with the Honda Type II motorcycle coolant. I have flushed the system tonight with distilled water.

My question is this:
Is this normal for this model?
Could the sensor for the temp gauge be bad?
Could the sensor for the fan be slow to come on?
If the thermostat was stuck closed, wouldn't it overheat in the morning as well?

If this was your motorcycle, where would you start to overcome this concern?

Your input, opinions, and suggestions are well appreciated in advance.
Thanks :biggrin:

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I know for a fact that my VFR runs warm, especially in stop and go traffic. My fan comes on at about 2/3 level.

If your fan is coming on, and you have confidence that the thermostat is operating properly (i.e. no terrible fuel mileage, taking a LONG time to warm up, and then BANG it's warm, etc.) then I would say that it's normal. A coolant flush and refill (that you are already doing) would probably benefit the bike, but probably won't affect the issue all that much.

Unless it's boiling over, I wouldn't worry about it personally, but I'll let a few of the VF500 owners chime in first, since these bikes seem to be a bit fragile when it comes to the cooling systems.

 

Your temp. gauge looks different than mine. The PO wired in a switch for my fan, so I thought it might have cooling issues. Let it sit, the fan still comes on by itself, at the right time. In hot weather, stop and go, mine got up at least as high as yours.

My brother got his hands on a infrared thermometer and we took that to it. With the gauge about halfway up (maybe even more) we were getting readings around 180 F which is where the thermostat starts to open. The fan isn't even supposed to come on til somewhere in the range of 220-230 if I remember correctly (please someone correct me if I'm wrong). So in my not-so-expert opinion I'd say you're OK, but wait for someone else to chime in.

 

idling at lights and stop-and-go traffic NORMALLY cause rise in temperature , and your bike is doing fine. as long as fan comes on and system is full, no problem, so don't worry.

there's a big difference between simply heating up and overheating......

 

Thanks for all the advice and opinions. I have purchased two bottles of Honda HP Coolant that will go into it tonight. I have also acquired an IR temp sensor to confirm actual numbers with the analog C-H temperature gauge. As it sounds now, this appears to be normal operation as long as its not boiling over, correct?

 

Real numbers update

OK, I completed the cooling system flush and refill with the Honda recommended HP Coolant. I let the bike idle as I topped off the coolant and let the bubbles settle. I re-capped the system and continued to watch the temperature increase. Using a Fluke digital IR temperature meter aimed at the hot water engine return feeding the lower part of the thermostat cover, I have validated that when the gauge reads normal, the real temperature is right about 180 degrees. As more time passed, the temperature continued to rise as indicated in my post to about the 3/4 hot mark. The radiator fan comes on when the thermostat housing reads 220 degrees and will continue to run until it drops to 210. The cycle continues on and off between the two readings with it never climbing above 222 degrees.

Since it never boiled over, I am going to assume that the data and the remarks from others appears to hold consistent with normal operations. I suppose I was just a bit over concerned, but this is my first water cooled motorcycle and I was rather comparing the gauge characteristics with that of an automobile that never seems to stray from the "normal" mark unless something is wrong.

I appreciate the information and help from others. I love this place! :thumb:

 

The picture you show is normal for stop and go traffic or when the fans are on. While riding it should stay right at the spot where there is the step in the bar behind the needle (if that makes any sense).

I'd try checking your radiator cap (often overloked).

 

Mine does exactly what yours is doing. the needle sits about 1/3 of the way up when I'm at speed on the freeway and at about 3/4 of the way in traffic and around town.

Nothing to worry about unless it's all the way up past the high temp line. Like Jamie said, if it gets to be an issue, I would flush the system, add new anti-freeze and check the cap, but I don't think you have a problem at all.

 

Nothing unusual as far as I'm concerned. VF500F's just run a little hotter than most. Mine is exactly the same.