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1986 VN750
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3,255 Posts
Discussion Starter #1
Hello all,

I have been riding around my local area at speeds of around 30-45mph with moderate stops/lights. The temperature is around 60F, and the bike takes upwards to 5-10 minutes to get to the first little notch on the temp gauge (even when I let it warm up a minute or two before going out - i've read here idling too long is bad as well so I figure that's safe). After another 10 minutes of riding it will hang around the 40-45% when I'm going at a decent clip.

Does the thermostat sound stuck open and making it take longer than normal to get to temp? I see many posts here with some conflicting information - that this is normal, and that it is not, and that some say sod it and throw a 80s honda accord t.stat on it w/ geo metro cap.

I saw a really clean replacement with cap is on ebay from a 06/5k miles for around $30. I'll grab it if it sounds like it's stuck open.

I appreciate any input. Thanks all!
 

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Premium Member
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3,026 Posts
I always warm mine up on the centerstand until the needle reaches that first mark on the right. I then ride very slowly until it has gotten a little past that mark. At 60 degrees, it can take 7-8 minutes easily for it to reach that mark while idling. In my opinion, idling is not that bad, as long as the choke is off. It would be better not to have to do it, but it is worse by far to take off with a cold engine. So I take the lesser of 2 evils, and warm it up completely. In cold weather, down in the 40s, I've seen the needle move quite a ways up while sitting at a stop light, then drop like a rock once you start moving again. Thats caused by the really cold air blowing over the radiator and engine, and carrying the heat away. That is the way it is designed to work, but in really cold temps, it can work a bit too well.
 

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If only it had 6th gear..
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1,100 Posts
Yeah in colder weather mine runs cool. Never gets near the halfway point, which it where the needle lives in normal riding weather. MC engines, being more exposed than car engines, fluctuate more more. I also allow mine to idle a little while in the colder temps mostly because of the damn clutch symptom but also because as Jerry said, it is worse to stress a cold motor.
 

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Registered
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I also allow mine to idle a little while in the colder temps mostly because of the damn clutch symptom...........
Are you talking about the clutch pads sticking and making the funny sound? I tried three different oils and when I put in Castrol 10/w40 it stopped after 10 minutes run time and hasn't done it again.
 

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Linkmeister Supreme
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7,960 Posts
I have lots of experience driving in cold weather. My last pick-up trick had a quilted vinyl weather front that snapped to the grill. Depending on the actual temperature I could open flaps more or less to allow what air was needed to keep the engine at the right temp.

I have also used a piece of cardboard for the same purpose, blocking direct airflow to the rad but with several inches between grill and rad to allow air to flow in from the sides.

On the Vulcan, the cardboard could be attached directly to the front of the rad, but you need to make a hole about 6" in diameter in the cardboard, that is centered on the fan blade. The hole needs to be centered in order to keep even stress on the fan blades when it is running. For example, if the hole was centered on the bottom half of the rotating blade, the stress on each blade would cause flexing back and forth from minimum to maximum with every revolution as each blade moves in and out of the airstream.

I am guessing on the size of hole needed in the cardboard on the bikes rad, but you can judge for yourself if the hole needs to be bigger or smaller by the temp gauge on the bike and how it responds as you ride. :smiley_th

I hope my word pictures are clear enough to understand the concept of blocking off part of the radiators cooling surface.
 

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Super Moderator
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11,816 Posts
I dont want to get into another arguement about warming up the bike or what constitutes "opperating tempature" but will say this....

If you can rev the motor without it stumbling, and the bike will idle at the suggested 1100 rpms smoothly ,without the choke on, and the tempature gauge is not showing the bike is overheating... You are good to go. Don't freaking care if the temp gauge moves at all... The bike is running smoothly.

If the gauge never moves I'd be worried it's broke, but the idea of covering the radiator with cardboard so you can get it to run as hot as it does in the middle of summer is the most ridiculous thing I have read on this forum over the years.
If you don't think your bike is hot enough, ride 10-15 minutes once the engine revs smoothly , then get off the bike, pull off your glove and wrap your hand around the cylinder. If it feels cold... Then you must be right...if you burn the crap out of your hand... Then the bikes working fine and you should kiss your tank and tell your bike you love it, because it's not running "Hot" stressing parts, breaking down it's oil, and not cooking off the thin coat of lube needed on all those rubbing surfaces.

The only reason to put cardboard over the radiator of your car (I'm leaving out diesel trucks this time) is to make the motor run hot do you can get the cars heater to get you warmer sooner. So covering a radiator on a water cooled bike that has no heating enclosure for the rider is plain silly.

Heat is what hurts your engine...not cold. Keeping it cool is the whole idea in having a "cooling system" in the first place. If it's very cold out, the system will work alot better, your motor will last longer and life will be good.

Yes, when it's very cold, you should wait until the oil warms up some, and the bike idles smoothly. Waiting for the motor to get as hot as it does during a 90 degree summer day is just increasing wear and burning fuel.

As long as the motor is still burning that fuel it will be producing heat, and once that heat spreads to the various parts of the motor, it is irrevalant what your temp gauge reads as long as it's not showing that the motor is over heating.

If you are worried about your thermostat you can test it by getting a candy thermometer and slowly heating your thermostat up in a pan if water on the stove. You can see when it just starts to open, and see the exact tempature it takes for it to this.
 

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If only it had 6th gear..
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1,100 Posts
Are you talking about the clutch pads sticking and making the funny sound? I tried three different oils and when I put in Castrol 10/w40 it stopped after 10 minutes run time and hasn't done it again.
Yup that's the noise.. and it grabs too. I thought I had tried castrol in it a couple of years ago but I'm willing to give it another shot. Eventually I'd like to get the Kevlar kit in there but have other stuff to do before that. Thank you though for the suggestion. :beerchug:
 

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1986 VN750
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3,255 Posts
Discussion Starter #8
Thanks for all the responses.

I'll probably just test my thermostat, but I am thinking it is working based on what everyone's said.

Today I had a few hour riding session and temperature would get warmer when I was in stop and go but would almost get down to first notch while going 45-50. I never seem to breach 40% or so - I'll keep an eye on it. It was fairly chilly holding around 60F still. I did feel the warmth between my legs at stop lights so it definitely was warmed throughout.

My bike idles fine after about a minute of 'warm-up' I usually let it sit another minute before going out - being easy on the throttle for a few minutes more.
 

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If only it had 6th gear..
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1,100 Posts
you're doin things right and your bike seems to be also. no worries :)
 

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Premium Member
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3,026 Posts
An oil temperature gauge would be a lot more beneficial for telling when an engine is warmed up than a coolant temp gauge. It gives a much more accurate indication of true engine temperature. My H-D has an aftermarket oil temperature gauge, it replaces the oil tank cap. It also takes several minutes to warm up. But unlike the new ones, it does not overheat in the summer, even here in AZ. It is jetted a little on the rich side.
 
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