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Thermostat issue?


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41 degrees F  at my house this morning, my 95 starts right up and a couple of miles later I am rolling down a local road at 80+, all good, runs like a champ as usual

about 12 miles later I notice the temp needle still hasn't come off the peg, I stopped for a school zone and it climbs up a needle width and then drops right back

down when I start to speed up.

 

My first guess is thermostat, second guess is temp gauge.

 

Any thoughts from the more experienced owners?

 

Thanks

 

 

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In the 19 years I had her, redslut's thermometer would hardly move. Most of the time. Only on say 26C+ days and giving it some welly/ride stop go traffic would it move over the half mark.

The 4th gens are known for this and I never worried.

Some added a resistor? to make it respond better I recall.

 

As long as the fan kicks in when needed you ate good to go.  Thermostat testing procedure is in the manual i think (never bothered myself)

 

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Ok Dutch, thanks for that.  It ran as if it was up to temp so I wasn't going to jump right in.  After my last Ducati, (999) which spent most of its time over 230 degrees and saying it was, this is a big change to be able to idle in traffic at OAT of 95 degrees and not be concerned.

 

Duc sure was pretty though

 

Thanks!!

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My '90 was like this when I bought it - actually I am not 100% positive the needle moved that single needle width or not, but I think it did. Anyway, consensus was to replace the temp sender - that it was a common issue. Sure, enough, that fixed it. Normal readings are now way below half range at about 25-30%.

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Mine was doing the same. I was doing other stuff so I drained the coolant, flushed with water, changed the thermostat, pulled and wiped off the sensors. After I refilled the system I taped the temp sensor that came with my multimeter to the hose on the right side of the bike. It came up to 186 or so and sat there, the fan would kick on and off.

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Great idea, I will do just that.  I have always thought this bike was running real cold because of the gauge but it runs like a fully warmed up bike

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Thought I would jump in here; on my '97 the temp gauge needle is normally about a quarter up when moving at speed, moves further upward when in traffic and the fans come on.  In other words, the needle moves  a lot and I think reflects the coolant temp accurately.  This is the end of my 3rd summer with my VFR and temp gauge has always been this way.  Of course when riding at air temps of 95+ F...the coolant does have to work.

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All VFR750's are like this. It's not until you've been riding it hard for a while then end up in London city center style traffic that it gets to the half way mark and the fan kicks in. I wasted a load of money on my first VFR750 thinking the thermostat was an issue...nope, wasn't, just the way the bike is.

 

I honestly reckon we could get rid of the oil cooler and there'd be no issue. Might run mine for a season without one and see how it goes.

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41 degrees F  at my house this morning, my 95 starts right up and a couple of miles later I am rolling down a local road at 80+, all good, runs like a champ as usual
about 12 miles later I notice the temp needle still hasn't come off the peg, I stopped for a school zone and it climbs up a needle width and then drops right back
down when I start to speed up.
 
My first guess is thermostat, second guess is temp gauge.
 
Any thoughts from the more experienced owners?
 
Thanks
 
 
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Had the same issue on both my 97 and 02 VFRs and my 94 Celica. All had thermostat stuck open which will cause the engine to run rich.

Sent from my HTC 10 using Tapatalk

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If it's the original thermostat, just replace it.  Should be a piece of cake.  

 

Your coolant temp should be around 174 degrees in normal riding and cool temperatures.  On really hot days it may get to 185-190.  220 degrees idling in traffic with fans on.

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I think there's a bit of exaggeration going on here. The VFR's ALL show a low needle rise, my 94 barely breaks an 8th in normal riding but hits half way on a summers day in stop start London traffic on my commute. To comfortably get at the thermostat, it's a carb off job along with a coolant replacement. I'd be very surprised if it's that and not just the normal behaviour of the engine temp indicator.

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I opened the bike up yesterday and looked at what it would entail to change the t stat, thought about how well it runs and thought "screw this" there will be a time I have more apart and I will get to it but for now I would rather ride. this is our season down here, right now!

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34 minutes ago, 750 said:

I think there's a bit of exaggeration going on here. The VFR's ALL show a low needle rise, my 94 barely breaks an 8th in normal riding but hits half way on a summers day in stop start London traffic on my commute. To comfortably get at the thermostat, it's a carb off job along with a coolant replacement. I'd be very surprised if it's that and not just the normal behaviour of the engine temp indicator.

 

I concur. I said my '90 reads on average 25-30% after the new sender. I remember now that when I bought it the needle didn't move at all. After the last couple of rides this past week, mine does indeed stay at about 1/8th on the gauge. Oh yeah, they also all smell rich at idle. Normal.

 

Cheers,

Glenn

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Thanks Glenn, that slightly rich smell bugs me but less and less.  This bike runs so good, never misses a beat from idle to red line, every time smooth as silk, 200 + miles per tank.

 

  I would rather touch nothing unless it needs it.

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49 minutes ago, bykemike said:

Thanks Glenn, that slightly rich smell bugs me but less and less.  This bike runs so good, never misses a beat from idle to red line, every time smooth as silk, 200 + miles per tank.

 

  I would rather touch nothing unless it needs it.

 

:fing02: There ya go. The only touching it needs now is your ass touching the seat!

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On 11/14/2017 at 9:17 AM, 750 said:

I think there's a bit of exaggeration going on here. The VFR's ALL show a low needle rise, my 94 barely breaks an 8th in normal riding but hits half way on a summers day in stop start London traffic on my commute. To comfortably get at the thermostat, it's a carb off job along with a coolant replacement. I'd be very surprised if it's that and not just the normal behaviour of the engine temp indicator.

 

It's not a carb off job on the 4th Gen, I'd say it's a couple hour job.

 

Mine never got warm, even in traffic after harder riding. Now it properly warms up like an engine should.

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17 hours ago, coupedupsubie said:

 

It's not a carb off job on the 4th Gen, I'd say it's a couple hour job.

 

Mine never got warm, even in traffic after harder riding. Now it properly warms up like an engine should.

 

The VFR750, be it third or fourth gen (I've owned several of each) will not have the temp gauge at anything above just off the white marker in normal riding conditions. People are obviously more than welcome to change the thermostat on their bike if they like...their time...their money, and all that.

 

But for anyone to suggest it's a requirement because the temp gauge doesn't go to half way like any other bike might, is bunk info and in most cases will be wasting peoples time and money.

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11 hours ago, 750 said:

 

The VFR750, be it third or fourth gen (I've owned several of each) will not have the temp gauge at anything above just off the white marker in normal riding conditions. People are obviously more than welcome to change the thermostat on their bike if they like...their time...their money, and all that.

 

But for anyone to suggest it's a requirement because the temp gauge doesn't go to half way like any other bike might, is bunk info and in most cases will be wasting peoples time and money.

Certainly agree with that, thermostat issues can usually be identified with a hand on the radiator as the bike is started from cold. If it is stuck open then you feel the radiator warming slowly from as soon as the engine is started, if it is normal the radiator stays cold until the thermostat opens, then the radiator very quickly gets too hot to touch. 

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On 11/22/2017 at 4:11 PM, 750 said:

 

The VFR750, be it third or fourth gen (I've owned several of each) will not have the temp gauge at anything above just off the white marker in normal riding conditions. People are obviously more than welcome to change the thermostat on their bike if they like...their time...their money, and all that.

 

But for anyone to suggest it's a requirement because the temp gauge doesn't go to half way like any other bike might, is bunk info and in most cases will be wasting peoples time and money.

 

Per the service manual:

 

Thermostat begins to open at 176F-183F, it is fully open at 203F.

 

In order to determine if it is working properly then it needs to either be removed an put in a temperature controlled heating pot or a digital thermometer needs to be attached to a line and the temperature monitored.

 

Were any of the 3rd/4th gens new? The only way to say how an engine in anything older is supposed to run is by looking at manuals or by having dealt with a new one. If you got them at 5 or more years old then I would say certain parts might already be failing. Look at the placement of both the 3rd and 4th Gen thermostat housings. One is under the carbs between the vee(3rd gen), the other is just inside the frame rail(4th gen). There was probably an issue noticed with the 3rd gen placement and Honda moved it to a more serviceable location for the 4th Gen.

 

All thermostat run cooling systems operate the same way, does not matter what the engine is. My brothers 03 919 just started always running cool this year, we will be replacing his thermostat this winter. 

 

If anyone who rides motorcycles values their money and time enough to complain about $50 USD to change a 4th Gen thermostat over a couple hours then they need to buy something new with a warranty. 

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Both my VFR's are over 20 years old - I've owned 2 others in the past. Neither of the current ones have had their thermostats replaced, I replaced the thermostat on my first VFR thinking it was dodgy, having not asked the simple question online, believing that all bikes should show a half way needle when at temp. I spent a fair whack getting it changed to no avail, it stayed the same...i.e. running normally. It would have cost me much more had the guy not been a bit of a dab hand and managed to do it without removing the carbs (this was on a 90 model). Neither  of the current ones overheat or run cold or oddly in any way, shape or form, none consumed more fuel than they should. I also had three of them ran on a dyno, all putting out the power they should - if that makes any difference to ya!

 

So, in essence, you're wrong for the largest part. There will always be a small chance of the thermostat going wrong - but you could say that about any bike that seems to show marginally different temp readings (because of course, the internet dictates everything should be the same across the board, regardless of the infinite amount of variations that owners encounter...right?). However, if you believe that the evidence above in itself isn't enough to prove the VAST majority do not require it being changed...well...you're a lost cause.

 

Also, if you think it's $50 to change a thermostat, you're out of your mind. It's a tank and carb off job on the 90-93 at a minimum unless someone who's highly adept is working on it. The 94-97 will still require the fairings off and a coolant change. I wouldn't trust it to anyone who's remotely spanner shy, either. The thermostat assembly on it's own is around £45 & delivery, add at least an hours labour just to pull fairings off and faff about with the coolant change and cost of it....

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Agree, 3vfrs & 2 hawks, they’ve all worked as 750 describes.  Resisted the impulse to “improve” their behaviour & correctly so I believe...

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On 11/25/2017 at 2:41 PM, 750 said:

Both my VFR's are over 20 years old - I've owned 2 others in the past. Neither of the current ones have had their thermostats replaced, I replaced the thermostat on my first VFR thinking it was dodgy, having not asked the simple question online, believing that all bikes should show a half way needle when at temp. I spent a fair whack getting it changed to no avail, it stayed the same...i.e. running normally. It would have cost me much more had the guy not been a bit of a dab hand and managed to do it without removing the carbs (this was on a 90 model). Neither  of the current ones overheat or run cold or oddly in any way, shape or form, none consumed more fuel than they should. I also had three of them ran on a dyno, all putting out the power they should - if that makes any difference to ya!

 

So, in essence, you're wrong for the largest part. There will always be a small chance of the thermostat going wrong - but you could say that about any bike that seems to show marginally different temp readings (because of course, the internet dictates everything should be the same across the board, regardless of the infinite amount of variations that owners encounter...right?). However, if you believe that the evidence above in itself isn't enough to prove the VAST majority do not require it being changed...well...you're a lost cause.

 

Also, if you think it's $50 to change a thermostat, you're out of your mind. It's a tank and carb off job on the 90-93 at a minimum unless someone who's highly adept is working on it. The 94-97 will still require the fairings off and a coolant change. I wouldn't trust it to anyone who's remotely spanner shy, either. The thermostat assembly on it's own is around £45 & delivery, add at least an hours labour just to pull fairings off and faff about with the coolant change and cost of it....

 

Well, the fact that your bikes produced the power they should on a dyno tells me a few things, that they are a clean engine that has proper ignition and had good fuel flowing through them. The only engines that heat is performance related is with a diesel engine. You paid someone to change your thermostat which is why you see it as a large expense. Should you be comfortable and have a general mechanical knowledge before working on your own motorcycle beyond changing light bulbs, yes.

 

Now, thermostats use temperature sensitive metals. They go bad over time, all of them. Its not a matter of if, but when. Every engine has a specified interval in which you are supposed to replace the thermostat. Some even say to remove it and test it on occasion to ensure it actually works as specified. This also goes for the coolant. Coolant is not a once and done thing. It can become acidic and eat away at different metals. When I drained mine it had a darker tint to it, it was quite old.

 

The internet is not my source of saying all thermostat based cooling systems operate the same, which is based on a specified temperature for the thermostat in that system. I have a bit more of a mechanical background to base that on. I work on everything from small gasoline engines to 3000+ hp diesel engines used in ships, as well as all the support systems needed for a ship to operate. It's my job to keep the ship I work on in proper operating condition so we don't hit the drilling vessel we sit 50 feet away from. I can strip all the fairings and the gas tank off my 94 in well under an hour, granted I have had practice with making a few repairs and changes.

 

What does having a gasoline engine come up to a proper temperature do for you? It helps maintain a proper oil temperature, this will keep fuel dilution and moisture build up to a minimum. 

 

I have realized that there are a few VFR common assumptions. Every small issue is blamed on the reg/rec, the PR4( or any of the PR tires) is the end all be all tire, and that because the majority of VFR750 owners have cooler running motorcycles then that must be how they are.

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19 hours ago, coupedupsubie said:

 

Well, the fact that your bikes produced the power they should on a dyno tells me a few things, that they are a clean engine that has proper ignition and had good fuel flowing through them. The only engines that heat is performance related is with a diesel engine. You paid someone to change your thermostat which is why you see it as a large expense. Should you be comfortable and have a general mechanical knowledge before working on your own motorcycle beyond changing light bulbs, yes.

 

Now, thermostats use temperature sensitive metals. They go bad over time, all of them. Its not a matter of if, but when. Every engine has a specified interval in which you are supposed to replace the thermostat. Some even say to remove it and test it on occasion to ensure it actually works as specified. This also goes for the coolant. Coolant is not a once and done thing. It can become acidic and eat away at different metals. When I drained mine it had a darker tint to it, it was quite old.

 

The internet is not my source of saying all thermostat based cooling systems operate the same, which is based on a specified temperature for the thermostat in that system. I have a bit more of a mechanical background to base that on. I work on everything from small gasoline engines to 3000+ hp diesel engines used in ships, as well as all the support systems needed for a ship to operate. It's my job to keep the ship I work on in proper operating condition so we don't hit the drilling vessel we sit 50 feet away from. I can strip all the fairings and the gas tank off my 94 in well under an hour, granted I have had practice with making a few repairs and changes.

 

What does having a gasoline engine come up to a proper temperature do for you? It helps maintain a proper oil temperature, this will keep fuel dilution and moisture build up to a minimum. 

 

I have realized that there are a few VFR common assumptions. Every small issue is blamed on the reg/rec, the PR4( or any of the PR tires) is the end all be all tire, and that because the majority of VFR750 owners have cooler running motorcycles then that must be how they are.

 

I'll be honest with ya, I'm starting to find you almost unbearably boring. So, I'll just leave it there, clearly we'll never agree.

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