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motormike

How Hot Is Too Hot?

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I rode 300 miles today. The last 60-80 miles was heavy traffic and there was quite a bit of stop and go on the interstate. Everyone coming home from cabins makes for heavy traffic.

The temp hit 235 degrees Fahrenheit and was very slow to come down even after getting back up to 40 mph and faster. I did pull off at one point for a rest and the temp cooled down to below 200. I think everything is okay but I'll have to check the coolant level to be sure. I know they can run hot but previously I haven't exceeded 228 degrees Fahrenheit so it was a little nerve racking especially since the temp was very slow to come down.

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235 is not unheard of. I was climbing the road to Mt St Helens today at about 75 mph (no lack of airflow) with the temp showing 225 (I had the fan switched to off). Once the grade leveled off it cooled down to about 210. Nothing to worry about. The temp not coming down while going 40+ is probably due to the fan being on and fighting the airflow. See the recent thread about installing a fan override switch. Since I did that I've had much better luck keeping things or getting them cooled down.

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My 5th gen runs right around 80C (176F) no matter how hard I flog it (and I do give it a right good seeing to up windy roads). In traffic/stopped is a different matter as with no airflow the temp will creep right up, at around 100C/212F the fan should come on, although I can't really say I've had this happen as I hate traffic and have only had the bike since autumn. My bike has 48k miles on it, and I have recently fitted a new thermostat (the old one was stuck half open (or half-closed for a pessimist). For the high temperatures that you folk are reporting I would have thought maybe your thermostats may also be stuck, impeding the flow of coolant to the radiators?

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I've seen my 98 at 245 after a 100°+ track day session. No ill effects as far as I can tell, but the actual cylinder head temp must have been pretty roasty at that point. Frequently seen it at 230-235 on hot days pushing it hard uphill in the lower gears. When slogging through slow traffic in the heat (it happens sometimes) I find that keeping the RPMs way down helps to keep it cooler. Short-shift, and coast whenever possible.

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Mine will hit about 225 sitting in traffic on a hot day before the fan will kick in and drop it down to around 215 or so. On level roads, it runs around 180-200 depending on ambient air temp.

235 is pretty warm, but doesn't seem out of whack for what these motors are designed for.

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I've seen temps in the 230's in similar circumstances. You only need to worry when it gets to 251. There is a brief discussion of high temps in fifth gen owners manual.

I believe you have nothing to worry about.

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I dont understand why a thermost controlled liquid cooled engine does not maintain a steady temperature. I have only been with my 98 for 3 days now. Have not heard the fan run yet and have seen coolant temps above 200. Just getting to know the bike now.

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I dont understand why a thermost controlled liquid cooled engine does not maintain a steady temperature. I have only been with my 98 for 3 days now. Have not heard the fan run yet and have seen coolant temps above 200. Just getting to know the bike now.

If you had an accurate temp guage on any automobile, you'd see they fluctuate a bit as well. The main difference is they are trying to save weight on a bike so everything is sized for the minimum. The DESIGN is that the fan comes on at 220 so that is isn't on all the time draining the electrical system constantly. If in proper condition, it easily drops the temp to 210, then lets it rise again & cycles in that fasion. Once moving & cooled down, you shouldn't see 200 at all unless it's in the high 90s & you're drafting a large automobile~

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Guest Recalcitrance

You're fine. That's not anything to worry about.

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I dont understand why a thermost controlled liquid cooled engine does not maintain a steady temperature. I have only been with my 98 for 3 days now. Have not heard the fan run yet and have seen coolant temps above 200. Just getting to know the bike now.

Maybe it will help if you understand why the thermostat exists at all in a liquid-cooled motor... Until / unless the motor comes up to the proper operating temperature, it isn't running optimally and performance is sacrificed. So, the thermostat remains closed until a "minimum" temp is reached where the motor starts to run better. And, even then, it isn't optimal.

As the motor speed varies, so does the circulation speed of the coolant - variations in temp will occur for this reason too.

There's nothing bad about what you're seeing. The motor was designed to work within those ranges.

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I dont understand why a thermost controlled liquid cooled engine does not maintain a steady temperature. I have only been with my 98 for 3 days now. Have not heard the fan run yet and have seen coolant temps above 200. Just getting to know the bike now.

Maybe it will help if you understand why the thermostat exists at all in a liquid-cooled motor... Until / unless the motor comes up to the proper operating temperature, it isn't running optimally and performance is sacrificed. So, the thermostat remains closed until a "minimum" temp is reached where the motor starts to run better. And, even then, it isn't optimal.

As the motor speed varies, so does the circulation speed of the coolant - variations in temp will occur for this reason too.

There's nothing bad about what you're seeing. The motor was designed to work within those ranges.

Of course I do understand why the thermostat exists. In fact I understood it 45 years ago.

I see you are in CT? Me too!

Anyway a liquid cooled motor can be built to tighter tolerance because it's operating temperature is (should be) so even. My automobiles with temperature gauges always ran at an even temp of about 180. If they got hotter something was wrong. That's what I am used to.

As I said this is my first liquid cooled bike AND my third day with it, at that. I am on the bottom of the learning curve with a long way to go.

BUT it seems like these bikes have an operating temp from 170 to 240 degrees. to me that's big. But if that's the way they are then that's the way they are I guess.

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Small motor (.8L), very small radiator, even smaller fan. Limited air flow potential for that fan. Seems like it all adds to up "have to allow for a wider heat range simply because that's just how it's going to work out." The smallest car motor I've ever owned was twice the size of this bike, and most have been at least four times the size at a minimum. And they all had much larger radiatiors in them with much larger fans (and less air flow restriction).

You're about a 45 minute (ish) ride from where I live - I'm West of Hartford.

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Small motor (.8L), very small radiator, even smaller fan. Limited air flow potential for that fan. Seems like it all adds to up "have to allow for a wider heat range simply because that's just how it's going to work out." The smallest car motor I've ever owned was twice the size of this bike, and most have been at least four times the size at a minimum. And they all had much larger radiatiors in them with much larger fans (and less air flow restriction).

You're about a 45 minute (ish) ride from where I live - I'm West of Hartford.

Yes more real estate(car) equals more options. We bikers take what we get and like it. And I do like it! I like it a lot!

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My 2 cents worth...the issue here is not the VFR's cooling ability (although with age, thermostat failures will change this) but rather the digital temp gauge. I've had water cooled bikes since 1983! They've all had a dial type gauge and indicated between 'C' and 'H'. Not the VFR...no reading until 35C, runs around 80C normally and the fan comes on at 100. I'll be honest and say I had NO idea what temp my earlier bikes ran at.

Sent from my iPhone using Tapatalk

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I finally checked the coolant level yesterday and it was fine. Then rode 300 miles and it ran wonderfully.

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What's a Fartenheat? I thought we lived in a metric world... :491:

Mine does a lot of slow traffic work at times, but I don't believe I've seen it get over 110 degrees Celsius. Or thereabouts. Maybe it's our maritime climate....

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I don't know why the whole world doesn't go metric

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