Over Heating VFR800

[igbell]

Hello All

I have a 1999 VFR800 that runs a little too hot.
I know they run hot anyway, but mine keeps boiling over in the summer or on long runs that have slow moving traffic in the heat.
I have cleaned out the pipes and also run cleaner through the Rad, and I have added the right amount of coolant and even added more coolant than needed, but I have still have the issue.
I have seen on other VFR sites that users have put 2 TL1000 fans on the 2 rads, one on the thrmostat and the other on a switch.
I have also seen people using WetterWater (or other versions), but then doing a lot of reading up I dont know if I fancy putting that into my machine...

Does anybody have any ideas please??? as I am going on a tour of ireland in June and didnt want to be calling RAC while I am over there.

[Dex]

I've not known of anyone personally having a problem with water wetter, but I know a few people using it in track cars who noticed an improvement in cooling.

Does the existing fan come on as expected at the temp it should? (is it wired in the right way so it blows air the right way?)

When you cleaned out the rad, did you flush it through both ways?

Just a thought, how many miles has the bike done, does it use any water, and have you checked head gasket?

[Gamer]

Fan have to suck in the air through radiator. (to improve the air flow)

Take thermostat out put it in to a pan with water and see if this is opening - should have 2 stages little gap at around 60 C and before boiling (94-96C) point fully open. (if not fully open it will block hot water in the engine - radiator should be much colder than the engine or gauge temp)

Is the water pump pumping? - low circulation will cause reduced cooling. And if thermostat was blocking water pump was under pressure and bearings might be gone.

Other thing - do not know the bike, but was it not designed like this? So without modifications it need to work

Just thinking loud Hope it helps

[Cemorah]

Do you hear the fan come on as it gets hot?

Yes then look at thermostat & water pump.
No look at temperature switch & fan.
Temperature switches usually close the circuit to earth so can be shorted using a short piece of wire and the fans will spin.

If you need help PM me I live in Cricklade and have a 750 and a short piece of wire .

[Jon_W]

Check the relife valve is ok. These can loose seal over time.

[igbell]

Thank you for all you ideas a few I have not looked at yet, so I will get on the case.
I went for a good long ride yesterday and yes the fan does come on as it is meant to at 104c and if I get rolling agin it cools down, I did check the thermostat out ages ago but I will get it out and boil it up again and see, I didnt think about the stat switch.
The old girl has 36k on the clock, and apart from this and the fact the clutch is very strong and makes my hand ache she is a good girl, oh and apart from when I bought her I could fill the tank on £15 and yesterday took £23 to fill her.

[Cemorah]

36K only just run in for one of these.

Heavy clutch - check slave cylinder piston & push rod for corrosion - remove re-lube and re-assemble.

Do you actually get steam pouring out of your bike and if so where?

I ask as it appears the stat switch is working at the correct temperature 104C the fans should stop when temp drops to 96C. normal operating temp 78-82C

Remember water under pressure boils at a higher temperature so 104C is not boiling up.

122C is what Honda consider to be the "danger" zone on this bike.

The fans on these bikes will cut in after only a couple of minutes in town and will cycle every 2-3 minutes.

As you say get on the move and they will cool to normal.

You did use distilled water to make up you coolant and mix it at 50% didn't you. Stronger mixtures not neccessarily better

S'funny I've noticed the petrol tank taking more money these days

[Mark_Able]

If the fan doesn't cool it down, it could be loads of crap blocking the fins in the radiator. Don't use a jet-wash, but spending some time with a hosepipe might be worthwhile... :-?

[MJJ_ZX6RR]

It could be something as simple as a faulty radiator cap, not maintaining pressure. This would cause it to run hot and use a bit of coolant.

A friend had the same on his CBR600RR a few weeks back.

New rad cap is a rather OTT £29 from Honda though.

Martin.

[Jon_W]

It could be something as simple as a faulty radiator cap, not maintaining pressure. This would cause it to run hot and use a bit of coolant.

A friend had the same on his CBR600RR a few weeks back.

New rad cap is a rather OTT £29 from Honda though.

Martin.

That's what I'm wondering. Had the same on my old mini.... used to boil up, turned out to be a perished seal on the rad cap.