06 VFR Running Hotter Than Normal

I have an '06 VFR with ~17,000km on it which I've owned for about three years now. The summer I bought it the bike would run in the low to mid 70 degC range at speed and up to the mid/high 80s in traffic, but midway through my second summer this increased to mid 80s at speed and ~100 in traffic. This is all in ambient temperatures in the 10-25 degC range in Canada, and I know these are normal temps for warmer climates but I'm getting a bit concerned. I know the bike isn't overheating, but a shift ~10 degC in all running temperatures is hard to ignore, and is always sitting in the back of my mind any time I gear up for a trip.

Once fully heated up the right hand radiator is blazing hot, while I can touch the left side and it barely seems to be above ambient at all..

Things I've tried so far:
- Checked/flushed all hoses & radiator: ran water through all hoses and found no sign of blockage, ran hot water through left radiator and confirmed I could feel relatively uniform warmth across the surface
- Flushed coolant + followed factory manual instructions for bleeding air/burping
- Removed thermostat: This is a bit confusing, I took the thermostat out and threw it in a pot of hot water, it starts to open at the right temperature, but at 97 degC I could only measure maybe 6mm (say +/- 1) opening on the valve, while the manual calls for "minimum" 8mm/0.3". Overall operation seems normal, and everyone I've asked laughs at me over a few mm but this is as much as a 25% variance from the manual.

Is it possible that just a 1-2mm reduction in the opening could be choking off coolant flow to the point that it isn't flowing into the left hand radiator? I also now suspect there could have been some residual air left in the system as I flushed it on the center stand last year, although the symptoms were the same before and after I flushed the coolant..

I guess my big question for now is, should I actually replace the thermostat over a measly 1-2mm reduction? Everything online seems to suggest thermostats either fail open or fail close, not "fail after 75%" so I'm not quite sure what to do, the bike is already in pieces and I certainly don't want to do that again any time soon if bleeding the air while leaning the bike hard from side to side doesn't work..

As a sidenote, many people have told me this isn't a big deal and to ignore it since the bike isn't overheating, but I see this as trying to hunt down something that could strand me in the future as opposed to tomorrow.

Thanks!

Cliffnotes: Bike runs 10-15 degC average higher than it used to without anything else changing, fluid/radiator/hoses are fine, thermostat is 1-2mm out of spec - replace?

 

Hi and welcome to the MadHouse:welcome:

A few things

When you get a chance swing by the "introductions" sub forum to say hello to the rest of the folks on here - and whilst you are at it post up at least one photo of your VFR as people will start ragging on you until you do.

Its also a good idea to update your forum profile to include the year/specs of your VFR and a rough location city/state will be fine. That way the information will appear beside all your posts and if you hit problems you may find someone nearby willing to swing by and offer help/advice in exchange for some beer tokens. As you will quickly discover we have a large and enthusiastic contingent of VFR owners in Canada, and if you are really keen you might catch up with a few at http://vfrworld.com/forums/showthre...-Day-Weekend-Reggie-s-Roadhouse-Roundup-v-7-0.

So with the housekeeping sorted:focus:, I think it is fair to say these bikes do run hot (once we get shot of all this snow) - and indeed the radiator on one side seems to always be hotter than the other - which I think is simply due to the coolant flow path through the radiators and therefore not of itself something to worry about.

You don't say whether or not you hear the radiator fan operating which really is important, so would be my first thing to check. On my 6th gen even wearing helmet and earplugs I can hear it clear as day with the engine running, so if you have not heard that come on, then it might be worth checking the fan works and the wiring is not defective. If you are worried about the thermostat then as they are not very expensive - I would just go ahead and fit an OEM replacement unit and make sure you don't have air trapped in the coolant circuit before firing her back up. If you are really worried about cooling her down then you will find you are in good company and LOTS of possible solutions have been tried over the years by forum members. The search function on the forum is actually quite good and should track you down plenty to think about such as this ..

http://vfrworld.com/forums/showthread.php/40195-5th-Gen-VFR800-Oil-Cooler-Swap?highlight=oil+cooler

Meantime good luck and let us know how you get on.




SkiMad

 

:welcome: to the zoo mate, Thanks Skimad :thumb:for a warm welcome to our noob and informative info.
Not sure what temperature you got but for us here in South Cal in the winter the temperature ranging from
155 to 175°F and in the summer the temperature from 185 to 225°F
Good luck and keep us posted.

 

The new temps are normal for canuck riding. Dont fret over 1 or 2mm as there is nothing wrong with the thermostat, if your not convinced then test a new one and compare.

Use the right type of coolant, aluminum engine with copper rads and steel cylinder sleeves mean we are limited to what we should use. Make sure your fan comes on and off at the right temps. If not try replacing the fan relay first. And watch your fingers!
If you want to drop a few without moding get some waterwetter. Found at canadian tire, various computer shops and I have seen it at walmart but no guarantee on that. Just follow the instructions and you will be fine, more is not better.
Last thing, you might want to clean the oil cooler, inside and out. Hotter oil temps mean that the water cooling system has to work harder.

Welcome to the asylum!

 

A relay, really ?? Earlier gens only have a fan switch on the radiator, no relay; is 6th gen different ??

Running hot?? You can always try replacing rad cap, thermostat, changing coolant.

 

No stock relay on my '03, thermal switch in radiator completes circuit to ground.

I added a switch and a relay (because of the current) to manually turn fan on.

I find riding around town at 30-35 mph, with the really long cycle time on the traffic lights, temps were getting too hot.

Now I can keep it in the 175-185 range most of the time.

 

There is a relay to supply power, your keyswitch controls it and the relay connects the battery to the fan circuit. This is why the fan does not run after shutdown.

 

I checked my wiring diagram, and there is no dedicated relay for the fan circuit. Fan wired directly to 20A fuse 'D' which is fed by Blue/Orange wire from ignition switch.
View attachment 25744
View attachment 25745
View attachment 25746

 

I dont think they changed them from 03 to 07, mine has abs so maybe thats the difference. I will have to pull the complete schematics out since I havent had to look at them in ages.

 

Just updated some wiring, rainy day project.

I added a manual switch to run fan, used the Hazard Switch from a newer bike. I used a relay and a flashing Red LED when on (right side).

Then I bought a LED Voltage monitor from RoadsterCycle.com, remounted it in the dash bezel (left side).

I remounted my HealTech Gear Indicator in the center. (Bike is on center stand in first gear).

View attachment 25755
Normal voltage.
View attachment 25756
Low voltage, fan is on but camera missed the on flash!

 

Thanks for all the responses!

I forgot to mention earlier, but the fan does come on normally.
It turns out I was measuring the thermostat opening wrong. For any first timers like me, I was only measuring the displacement of the large valve on top when I should have been measuring total change since the bottom opens too as seen on page three here: http://www.hella.com/hella-za/assets/media_global/HASA_Thermo_Range_Borchure_LRes.pdf

Total displacement came out to 9.5mm, so the thermostat is A-OK. On one hand that sucks since I spent the time tearing it out, on the other hand it was a good learning experience and I know a hell of a lot more about cooling systems than I did last week.

Up next put it all back together and be super super vigilant about air in system!


As a sidenote, while disassembling the bike I made sure to take a picture of each step and then put them in a document in reverse order to use as a reference when putting it all back together. To avoid needing to bring my computer into the garage I sent it off to the staples print & copy center so I'd have a nice colour guide, when I picked it up the envelope was marked "Good Luck".

 

At what speed/rpm does it get hot? Has your driving habits changed? Like I said earlier, when I ride in populated areas with a 30-35 mph speed limit, I am running at 3K or higher RPM, and temps begin to climb, add to that the traffic lights all have turn lane lights which makes for long waits. Once I get rolling above 35-40 mph, it runs cooler. I think it is more air flow a lower speeds than anything else, that is why I added manual switch. I use switch at lights primarily because air flow from fan is opposite of normal cooling, so at some speed there would be an equilibrium and no cooling. My bike is 10 years old and 30K miles, running hot hasn't seemed to bother it, but it bothers me!

 

I never understood why the fan draws air through the rad outside to inside and then when we ride the air flows inside to out. Who on the engineering team thought that up? Or do we blame management for getting the wrong dc motor? If we can make it turn the other way then it would be fine. . . . I guess the best is to swap fan blades like some have already done.

 

An easy coolant system test most folks don't bother with is a pressure test. Tool plugs up at radiator cap with different adapters. Will tell you if you've got a leak somewhere.

 

The only reason I can think of that the air flow is reversed with the fan is at low speeds, it is better to pull cold air across radiator from the outside. There isn't any air flow in traffic or low speeds, so pulling hot air from cavity in front of engine is not as efficient in cooling. As speed of bike increases, air flow from the front and the venturi effect pull air from the inside out. I am sure that around 35 mph there is an equilibrium. I checked my manual and the water flows into the right radiator first, then to the left radiator, then back to engine. better to have fan on left, for maximum cooling, and that is why the right is hotter, normal condition.

Might also be a product liability problem, with the fan blowing really hot air on the riders leg while stopped! Especially if some yahoo was wearing shorts.