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Running temp for 06 VFR800 vtec


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Hi there. 
im new to the VFR800 world but far from new to motorcycles 

I have recently acquired a neat example of the VFR800 but the bike seems to be running quite hot. 
I have change coolant and cleaned k&N filter. 
flushed it and it doesn’t boil. 
bike sat for almost 2years prior to me buying it. 
going for a decent run in temps above 30 degrees Celsius the bike got as high as 112 C 

didn’t get hotter but didn’t come down. 
can anyone tell me if there’s still a likely issue here or is that the normal operation temp of this type of bike

 


 

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Hi Gezza.

Welcome to the forum. Better post a pic of your ride.

Hope you're nowhere near the terrible fires!

 

VFR's do run hot. In stop/start traffic no matter what the ambient temp, engine temp will rise to the point where the cooling fan will cut in, and this is at around 102 - 104degC. From memory while riding if the ambient temp is around 25degC or less, the bike temp would be around 78 - 80deg but once the ambient temp gets above 30deg so too does the engine temp start to rise.

 

The important issue, does your thermatic fan kick in around the 102 -104degC?

 

Can't say I've ever seen 112degC with any of my 6gens.

So first check your fan ops. Failing that you may have a thermostat issue, or air in the system, requires burping after coolant replacement, also check the overflow tank that the coolant level is correct.

If your fan isn't working you may have a blown fuse (Fuse D, 20amp Fan Motor), faulty thermo switch or dead fan.

Lets know how you get on.

 

You can also download the full Service Manual from this forum if you don't already have one.

 

Also if your bike has sat for 2 years, suggest you flush your Brake and Clutch fluid ASAP.

 

Cheers from Victoria.:beer:

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Welcome Geeza!

 

yes as Grum mentioned, 112C is quite high. You'll want to verify fans turn on at around 104C and temps drop.

 

At cruising speeds with plenty of airflow, around 80C

 

There's procedure in manual for testing thermostat and fan-switch. Follow those procedures and determine if thermostat and fan-switch are operating properly.

 

Don't just replace them because you will not have pinpointed cause of overheating. Replacing perfectly working-parts with brand-new perfectly working parts won't change anything. With low-quality of replacement parts, those new parts should be tested before installing anyway.

 

Did you change oil & filter?

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Hiya Gezza...

If you see *continuous* temps higher than 220ºF (104º) or below 180ºF (82ºC) then trouble shooting is in order:

 

Continuous engine temps above 220ºF or 104ºC is a problem and the proper
order of items to trouble shoot are:

 

1)Faulty radiator cap... system should hold 1.1 pressure ratio...
2)Insufficient coolant...
3)Passages blocked in the radiator, hose or water jacket...
4)Air in the system...
5)Thermostat stuck closed...
6)Faulty temp meter or thermo sensor...
7)Faulty fan...
8)Faulty fan switch...

 

Engine temps below 180ºF or 82ºC is also an problem... it means that the
moisture produced during combustion is not getting hot enough to
evaporate out the pipe as steam... instead that moisture will migrate
to the oil and produce a milky white contamination...

 

Note normal by products of combustion is water... . Every gallon of gas
creates roughly 8 pounds of water vapor... we all have witnessed water
escaping out of tail pipes on cold mornings...

 

The sequence of events to trouble shoot are:

1)Faulty temp meter...
2)Thermostat stuck open...
3)Faulty fan switch... (stuck on)

 

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Hi guys 

 

awesome response so thanks for that!

Had another ride today to see what the milder ambient temp today affects the running temp and had a slight improvement. 
bike sits at around 100- 106 Celsius while cruising at highway speeds and the fan is kicking in at approximately 104 as per normal. 
noticed it does fluctuate and did get as high as 112 while at the lights but seems to reduce quickly once on my way. 
when flushing the coolant I noticed that the amount of air in the system wasn’t significant but it did vent slowly and I blipped as per the instructions. I haven’t noticed a drop in level in either the overflow or the RHS radiator at the cap

the cap was dirty and needed a clean but seems to be in good order. 
 I’ve owned many bikes over the years 4 blackbirds and a hyabussa, old ZZR’s  but this is the first side mounted radiator I’ve had. 
the local Honda guy said the temps are normal and his idea on changing the readout to the ambient temp display tells me he’s a head in the sand type so not too happy about that. 
if there’s a way of checking the performance of the thermostat without dismantling the bike ide be interested. 
 

love the bike so far and especially that fun zone at 6500rpm so I think once I have this cooling situation under control I’ll be happy as!
fires are close but we’re all good!

 

38D09559-2325-4A54-BBF1-277EC89C3704.jpeg

AD7C2691-EE13-458C-81A9-1382CBE2E29E.jpeg

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Well, proper test of thermostat is to boil it in water and watch it open. Then record opening-temp. So not sure how to do that on bike as thermostat needs to be removed from housing to observe.

 

Difficult to test thermostat function when installed on bike and even more difficult to stick thermometer in exact spot it occupies.

 

uc?export=download&id=1-SN4OMpWy7_qvcUM0

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I thought that may be the case. 
I figured if it wasn’t working at all the bike would overheat fairly quickly 

when I changed the coolant I ran the bike up to temp and the coolant level dropped suddenly so I assume that was evidence of the thermostat opening. 

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Why not test thermostat while you've removed radiators? Thermostat "opening" is not binary value, there's actual valve-travel amount. And if yours isn't opening fully, it will restrict flow at operating temperatures. Bike and manual were designed by very intelligent engineers. Their tests are meant to get to root of problems precisely and quickly.

 

Another easy test is to verify radiator-fans running properly. Heck, you may have broken wire or unplugged connector somewhere. Here's test right out of manual:

 

uc?export=download&id=1LJ9mPfaOWpTWctJ_5

 

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1 hour ago, Gezza1970 said:

bike sits at around 100- 106 Celsius while cruising at highway speeds and the fan is kicking in at approximately 104 as per normal. 
noticed it does fluctuate and did get as high as 112 while at the lights but seems to reduce quickly once on my way. 

Nice looking bike Gezza, but I don't think your cooling system is up to scratch!

 

I've ridden in well over 30degC conditions and cruising along at highway speeds I've never seen temps you're quoting. Your statement of a dirty radiator cap concerns me. If the correct coolant maintenance was done previously, it would be spotless. So you may need to investigate your radiator core cleanliness, and check the thermostat operation.

 

Sounds like you're confident the thermatic fan is kicking in at the right temp.

 

Just for info I've always used Honda Type 2 premixed coolant, both borate and silicate free. Available at any Honda car dealership spares department.

 

Good luck. Keep safe and away from the fires.

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My crude thermostat test is to start the bike from cold and keep a hand on the right radiator. If it heats slowly from the get-go, it is stuck open, and you are up for a few hours of open-bike surgery to lift out the throttle bodies for access to the housing. I'd replace some of the hoses if you get that far in, you won't want to go back in a hurry, and the thermostat removal may cause some subsequent leaks (mine did).

 

Normal operation is for the thermostat to stay shut until the coolant in the block exceeds around 80C (so the radiator stays cold), then it opens and dumps hot coolant to the radiator (which will quickly get too hot to touch). If the bike passes that test I would be looking elsewhere, and the next easy fix is the radiator cap. If it won't hold pressure you get localised boiling and that is much less effective at cooling than nice liquid flow.

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3 hours ago, Grum said:

Nice looking bike Gezza, but I don't think your cooling system is up to scratch!

 

I've ridden in well over 30degC conditions and cruising along at highway speeds I've never seen temps you're quoting. Your statement of a dirty radiator cap concerns me. If the correct coolant maintenance was done previously, it would be spotless. So you may need to investigate your radiator core cleanliness, and check the thermostat operation.

 

Sounds like you're confident the thermatic fan is kicking in at the right temp.

 

Just for info I've always used Honda Type 2 premixed coolant, both borate and silicate free. Available at any Honda car dealership spares department.

 

Good luck. Keep safe and away from the fires.

Thanks Guys

 

I might need to drop the coolant again and change it for he Honda variant 

Ill also change the cap and pull off the bottom hoses to see what I can find as far as dirt and build up. 
It’s simply going to be a process of elimination and I’m sure eventually I’ll get it under control. 
it’s a smooth ride so I’m still happy 

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The choice is yours, but choosing a 30 grade over a 40/50 grade is smarter because it will:

1)increase 2 to 3 HP at the rear wheel
2)quicken the throttle response coming out of the corners...
3)decrease over all operating temps...
4)increase the oil flow at the critical bearings...

 

Either a 30 / 40 / 50 grade will reach your mileage expectations but only a full
synth 30 grade will lower your operating temp because it flows with
less drag than a 40 /50 grade... oil drag is real...

 

RC45Grade30.JPG

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That's a pretty cool colour! Is it factory option?
 

AD7C2691-EE13-458C-81A9-1382CBE2E29E.jpeg

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2007 in the States

spacer.png

 

Always thought they screwed up that year though.  This frame treatment should have gone on the RWB Anniversary model, and the blacked out frame would have look lovely with the dark red.  I almost convinced the Sales Manager to let me swap bodywork and wheels on two new ones for sale.

 

spacer.png

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19 hours ago, Gezza1970 said:

Hi guys 

 

awesome response so thanks for that!

Had another ride today to see what the milder ambient temp today affects the running temp and had a slight improvement. 
bike sits at around 100- 106 Celsius while cruising at highway speeds and the fan is kicking in at approximately 104 as per normal. 
noticed it does fluctuate and did get as high as 112 while at the lights but seems to reduce quickly once on my way. 
when flushing the coolant I noticed that the amount of air in the system wasn’t significant but it did vent slowly and I blipped as per the instructions. I haven’t noticed a drop in level in either the overflow or the RHS radiator at the cap

the cap was dirty and needed a clean but seems to be in good order. 
 I’ve owned many bikes over the years 4 blackbirds and a hyabussa, old ZZR’s  but this is the first side mounted radiator I’ve had. 
the local Honda guy said the temps are normal and his idea on changing the readout to the ambient temp display tells me he’s a head in the sand type so not too happy about that. 
if there’s a way of checking the performance of the thermostat without dismantling the bike ide be interested. 
 

love the bike so far and especially that fun zone at 6500rpm so I think once I have this cooling situation under control I’ll be happy as!
fires are close but we’re all good!

 

38D09559-2325-4A54-BBF1-277EC89C3704.jpeg

AD7C2691-EE13-458C-81A9-1382CBE2E29E.jpeg

 

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Thermostat must be working it is VERY DIFFICULT to remove, lies between cylinders under throttle body. Thermostat should open at 170 F, watch the temperature gauge when warming up the engine and place a hand on the radiator. Also, fuel trim/O2 sensors tends to lean the engine under steady throttle, a factor in running warmer/hot. I usually see the engine run 170-180 F when ambient temps are under 60 F, stopped in traffic will climb to 220 F, fan should turn on. On warm/hot days, highway temps will climb to 190 F.

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Candy red is indeed a beautiful color on those bikes.  IIRC Honda used that same color on the 2001 Blackbird in the U.S.  market. 

 

In the "running hot" threads I can recall over the years regarding 5th and 6th gens, the consensus seems to have been that as long as everything is in good nick as above, and as long as it's running at 110C or below, just ride it.  The only exception to that I've found is that if going down the road at speed it refuses to cool down, it's probably because the fan was still running as speed came up. The fan stalls airflow over the left rad significantly reducing cooling ability.  I installed a fan over-ride switch for that eventuality - but it's fairly rare.  If it's 115C it's probably time to stop and let it idle a bit to cool, and if it's 120C it's definitely gotten way too hot and needs to be shut off.

 

One other thing - if the system was bled while on the center stand, try it again with it on the side stand.  Doing the latter makes the cap the highest point in the system ensuring all the air is out.  On the c-stand, the upper hose that connects the two rads is parallel to the ground and all the air may not be expelled. 

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Thanks Cogs 

 

I’m a little less worried now as I’ve just had a burst up the highway and it never got above 100C 

seems to be improving with each ride and I guess the fact that it sat unloved for two years has contributed to this issues I’m having. 
just one other question from a new to VFR guy 

when rolling the throttle on in 5th or 6th there’s a significant flat spot at 6500rpm 

this seems to be just as the vtec takes effect. 
is this the norm or should a tune and Dyno be done to try and eliminate it?

it’s a fairly smooth Revving bike so it’s quite noticeable 

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1 hour ago, MarcOtt said:

Thermostat must be working it is VERY DIFFICULT to remove, lies between cylinders under throttle body. Thermostat should open at 170 F, watch the temperature gauge when warming up the engine and place a hand on the radiator. Also, fuel trim/O2 sensors tends to lean the engine under steady throttle, a factor in running warmer/hot. I usually see the engine run 170-180 F when ambient temps are under 60 F, stopped in traffic will climb to 220 F, fan should turn on. On warm/hot days, highway temps will climb to 190 F.

Hi mate 

 

I had the bike on the side stand when bleeding the air out. 
the bike does seem to be running on the upper end of the temps you quoted but improves with each ride so I’ll just monitor it and see what happens 

 

thanks though. 
any help and feedback is apprec

18 hours ago, Terry said:

My crude thermostat test is to start the bike from cold and keep a hand on the right radiator. If it heats slowly from the get-go, it is stuck open, and you are up for a few hours of open-bike surgery to lift out the throttle bodies for access to the housing. I'd replace some of the hoses if you get that far in, you won't want to go back in a hurry, and the thermostat removal may cause some subsequent leaks (mine did).

 

Normal operation is for the thermostat to stay shut until the coolant in the block exceeds around 80C (so the radiator stays cold), then it opens and dumps hot coolant to the radiator (which will quickly get too hot to touch). If the bike passes that test I would be looking elsewhere, and the next easy fix is the radiator cap. If it won't hold pressure you get localised boiling and that is much less effective at cooling than nice liquid flow

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13 hours ago, Gezza1970 said:

Thanks Cogs 

 

I’m a little less worried now as I’ve just had a burst up the highway and it never got above 100C 

seems to be improving with each ride and I guess the fact that it sat unloved for two years has contributed to this issues I’m having. 
just one other question from a new to VFR guy 

when rolling the throttle on in 5th or 6th there’s a significant flat spot at 6500rpm 

this seems to be just as the vtec takes effect. 
is this the norm or should a tune and Dyno be done to try and eliminate it?

it’s a fairly smooth Revving bike so it’s quite noticeable 

If you look at a dyno graph of a stock 6th gen, there is a bit of a dip in the curve at that 6,800 rpm point.  I suppose the sudden opening of the other 4 intake valves results in a brief lean condition that the rider feels as a flat spot or "VTEC transition".   For a dyno tune you'd need an aftermarket unit to modify the ECU's output.  Most people, including me, have tried Power Commanders - and for sure a dyno shop can use that to alter the fuel delivery.  However, it's static, once set that's it.  You can get the Autotune module for it, however you have to take a ride, look at the adjustments it makes then either accept or discard them, then ride again to see how it's doing.  It will remain that way until you go through that exercise again.  The other choice is what I tried last year - Rapid Bike.  R.B. plugs in to your two stock O2 sensors and adjusts to a target AFR on the fly.  So changes in altitude, air filter, exhaust - whatever, are adjusted for in real time.  Way ahead of P.C.  I thought I had my P.C. in good order - and it was.  When I installed the R.B., it was immediately better, that dip smoothed over even more and I picked up some fuel efficiency.  IMHO R.B. has an outstanding tune right out of the box that will get even better as you ride it.  I wish I'd done that rather than P.C. in the 1st place.  At any rate - that is really all a tuner is going to do - so with a R.B. you can likely get as good a result without paying someone additional money.  The worst that happens is that you take it to a tuner anyway, and they'll probably like that you have the R.B. unit.   R.B. has a US distributor in Florida you can email and you can also visit their website. 

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Thanks for that mate

 

seems there’s a distributor in Australia so I’ll chase them up. 
There’s several different options but the smart option is the unit you are describing. 
I’ll get a quote and go from there. 
I’ll let you know how I go and send you some feedback 

 

cheers once again. 
if we’re ever able to travel again then pop over to Aus and we’ll go for a spin!

🙂 

 

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