Overheating VFR400 NC30

[I14]

I've just got my "new" NC30 onto the track for Taupo, weekend before last, and it sufferred from overheating. Since I've been home I've pulled off the radiators and had a good look at them. The top one was in pretty good shape but the bottom one had an area covering the middle half roughly that you couldn't see through. I sat in front of TV with a strong needle and straightened most of the little vanes then water blasted it and now it looks fairly clear. I also removed the thermostat (the fan is off already).
My question is should I fit a higher pressure radiator cap assuming one is available? I know you lose power when the motor gets hot so it's better to cure it at source but it only gets close to the red zone when you come back in when a higher pressure cap would help it not boil over? Also is there a maximum temperature before you do serious motor damage?":

[neil_cb125t]

I've just got my "new" NC30 onto the track for Taupo, weekend before last, and it sufferred from overheating. Since I've been home I've pulled off the radiators and had a good look at them. The top one was in pretty good shape but the bottom one had an area covering the middle half roughly that you couldn't see through. I sat in front of TV with a strong needle and straightened most of the little vanes then water blasted it and now it looks fairly clear. I also removed the thermostat (the fan is off already).
My question is should I fit a higher pressure radiator cap assuming one is available? I know you lose power when the motor gets hot so it's better to cure it at source but it only gets close to the red zone when you come back in when a higher pressure cap would help it not boil over? Also is there a maximum temperature before you do serious motor damage?":

Fitting a higher pressure cap simply holds the heat water in longer.... meaning the water won;t go to the overflow bottle till it gets hotter.... and puts more pressure on the cap.

fans are good to stop the heat getting up at the end of the race - try a good proven race coolant but you may need more cooling ie bigger rad.

red is bad when it comes to heat - too hot = big damage.

[Nicksta]

i had the same issue for a while, do you run the fan? what temp is it at while at track/race pace? does it overheat only on cool down lap or coming into pits?
if you run total loss, think about installing the fan again, but putting it on a switch you can flick on if needed (i switch mine as soon as i cross the line)....

[HenryDorsetCase]

I would definitely reinstall the fan. It is noticeable on mine as well. they do have a reputation for running hot also so anything you can do to help the poor wee thing out is good. I'm using that very expensive Fuchs race coolant (which is racetrack legal apparently i.e. non glycol) and I think its better than the green stuff that originally came out when I changed it.

[lostinflyz]

yea mines overheats every now and then. Often the water can drop a bit low. Often ill fill mine way up and let it overflow a shitload.

You can get race rads they use in aussie for their summer for the top radiator to keepthe temps down, i think there like 400 aussie bucks off the top of my head.

If the days over about 25 degs. then they run pretty hot, esp when you are on the pit return. Fit a digital temp gauge and know what it actually is i would suggest. Mine will sit at close to a 100 degs on the grid waiting for a race. Once over that i shut it off till we start moving, when the temp should plumment again.

Otherwise have you got a dorked heat gasket>??>

[lostinflyz]

on the question of max temp, the water can be watever it wants, its the oil getting too hot that causes it to rapidly degrade. I think most standard oils its about 120 odd degrees. In my mind i only get worried when the water temp gets over about 105. My fireblade through town would sit at about 102.

[I14]

[
fans are good to stop the heat getting up at the end of the race - try a good proven race coolant but you may need more cooling ie bigger rad.

red is bad when it comes to heat - too hot = big damage.[/QUOTE]

Thanks Neil, I'll refit the fan
Phil

[I14]

i had the same issue for a while, do you run the fan? what temp is it at while at track/race pace? does it overheat only on cool down lap or coming into pits?
if you run total loss, think about installing the fan again, but putting it on a switch you can flick on if needed (i switch mine as soon as i cross the line)....
Thanks Nicky. At race pace it was about 95C but got up to 100C on cooldown lap as I came into the pits then boiled over. I raced for 1 race without the fairing and it ran at 90C. Short track 2 so no disadvantage then took to the fairing with a hacksaw at lunchtime but it still ran too hot as above with the fairing back on. I've still got the alternator so no probs to refit the fan.
Phil

[I14]

I would definitely reinstall the fan. It is noticeable on mine as well. they do have a reputation for running hot also so anything you can do to help the poor wee thing out is good. I'm using that very expensive Fuchs race coolant (which is racetrack legal apparently i.e. non glycol) and I think its better than the green stuff that originally came out when I changed it.
I'm using the Maxima Cool-Aide, red stuff. $15 for 1.9L. It claims to do everything including winning the race so must be good stuff!

[I14]

yea mines overheats every now and then. Often the water can drop a bit low. Often ill fill mine way up and let it overflow a shitload.

You can get race rads they use in aussie for their summer for the top radiator to keepthe temps down, i think there like 400 aussie bucks off the top of my head.

If the days over about 25 degs. then they run pretty hot, esp when you are on the pit return. Fit a digital temp gauge and know what it actually is i would suggest. Mine will sit at close to a 100 degs on the grid waiting for a race. Once over that i shut it off till we start moving, when the temp should plumment again.

Otherwise have you got a dorked heat gasket>??>
That sounds pretty similar temps. Where can you get a digital temp gauge? I think with the standard 1.1 Bar cap it will overflow at 105C? What pressure cap do you run? I don't think I've got a blown head gasket as it ran just fine with the fairing off. In this case I believe the fairing is restricting the rate that heat gets away rather then limiting the air coming in. I think I proved that when I 'surgically modified' the fairing at 1/2 time.

[lostinflyz]

That sounds pretty similar temps. Where can you get a digital temp gauge? I think with the standard 1.1 Bar cap it will overflow at 105C? What pressure cap do you run? I don't think I've got a blown head gasket as it ran just fine with the fairing off. In this case I believe the fairing is restricting the rate that heat gets away rather then limiting the air coming in. I think I proved that when I 'surgically modified' the fairing at 1/2 time.

shit man ive gone through a number of radiator caps now i have no idea what it runs at. If its not over about 98 during the race i wouldn't care. I treat the boil over merely as a sign that it is hot and shouldn't sit round running, rather than a bad sign.

Daytona digital temp gauges are all i know of. i reckon there pretty garbage as there pretty fragile.


i go with the opinion that if it lives through the race the cool down lap will be a nice change, even if it gets a bit hotter. I found at nelson last year (prob close to 40 deg on track) that i run the cool down lap with the revs really low and little throttle but high corner speeds to try and get the temp down before i got to the pits. but it was still clocking 100 plus

[lostinflyz]

actually on that i was staring at M1 fotos the other day and seeing the big radiator outlet vent, maybe theress something to that ey. Might make a few prototypes up to try out of nats if i can be bothered.

remeber that the top rad feeds directly into the V above the motor and under the tank so theres a good heat bed for heat to soak into the motor and ramp up temps.

[koba]

I also removed the thermostat (the fan is off already).

Put it back in, It creates a restriction to raise the pressure in the hottest parts of the engine. Do some reading on it.

If there is signs of corrosion inside flush the shit out of the cooling system, maybe even take it to a radiator place to get all the scaly shit of the inside of the radiators and passages.

Make sure it is bled correctly and no air is in it.
Also check the water pump is in good nick and the head gaskets are sweet.

EDIT: Make sure the thermostat works before you put it back in, drop it in a pot of boiling water and make sure it opens.

[I14]

Put it back in, It creates a restriction to raise the pressure in the hottest parts of the engine. Do some reading on it.

If there is signs of corrosion inside flush the shit out of the cooling system, maybe even take it to a radiator place to get all the scaly shit of the inside of the radiators and passages.

Make sure it is bled correctly and no air is in it.
Also check the water pump is in good nick and the head gaskets are sweet.

EDIT: Make sure the thermostat works before you put it back in, drop it in a pot of boiling water and make sure it opens.
Cheers Koba. I took it to a radiator place and they told me that these aluminium radiators are sort of fusion welded when they are assembled and only some service places have the gear to re-assemble (reweld) them after cleaning out. I'd better do some reading as normally the more water that goes past a heat source I guess in laminar flow conditions the more heat is conducted away? That is it is more flow then pressure related? Seems to be plenty of flow now that the thermostat is out so it looks like the water pump is running OK. As for the head gaskets well there's no obvious signs of gas getting into the water system. I'll check the thermostat.

[koba]

Cheers Koba. I took it to a radiator place and they told me that these aluminium radiators are sort of fusion welded when they are assembled and only some service places have the gear to re-assemble (reweld) them after cleaning out. I'd better do some reading as normally the more water that goes past a heat source I guess in laminar flow conditions the more heat is conducted away? That is it is more flow then pressure related? Seems to be plenty of flow now that the thermostat is out so it looks like the water pump is running OK. As for the head gaskets well there's no obvious signs of gas getting into the water system. I'll check the thermostat.

Its about pressure.

Water at amospheric pressure boils at 100 degrees C.
In a system with a 14psi Radiator cap the boiling point becomes around 125 degrees C.

The restriction of the thermostat in the system can raise pressure behind it to 30-40psi above that thus raising the boiling point in the hotter parts of the engine.

Without that restriction it doesn't get the localised pressure build up and will begin to boil in the hottest areas, thats a bad thing.

[vagrant]

You should be able to flush it without taking the end tanks off. If it is that bad, try Kumue radiators. The place looks a complete mess but he does great work. Rebuilt the racekit rads for my RC30 after the couriers pretty much stuffed them.

The other thing you could try is fitting an electric waterpump (like this one) (http://www.daviescraig.com.au/Electric_Water_Pumps-content.aspx)in place of the engine driven one. It will give you a higher flow rate than when the engine is at low revs, and you can leave it and the fans running after you shut the engine down.

[lostinflyz]

hey man,

before you go too far on fixing up stock rads, they are borderline on a hot day if they are perfect and your ringing the nuts off them.

Fixing a radiator will prob cost you little less than buying a proper race radiator (top only) that will cure all issues. RB imports in aussie sell them for 475 AUD, usually they have them in stock. When i talked it through with them basically they found these to be the best option for there forumla 400 class in aussie head.

HRC did an oil cooler for them as well to keep them cool in Japanese F3 competition use. You can retrofit other bikes(cbr600f4 is common) oil coolers without tooo much hassle.

but again man 100+ or boil over is not really an issue if its only on dummy girds or when you make it back to the pits. If it doesn't overheat during the race alls good.

[I14]

Its about pressure.

Water at amospheric pressure boils at 100 degrees C.
In a system with a 14psi Radiator cap the boiling point becomes around 125 degrees C.

The restriction of the thermostat in the system can raise pressure behind it to 30-40psi above that thus raising the boiling point in the hotter parts of the engine.

Without that restriction it doesn't get the localised pressure build up and will begin to boil in the hottest areas, thats a bad thing.
OK that makes sense thanks, I'll stick the thermostat back.

[I14]

You should be able to flush it without taking the end tanks off. If it is that bad, try Kumue radiators. The place looks a complete mess but he does great work. Rebuilt the racekit rads for my RC30 after the couriers pretty much stuffed them.

The other thing you could try is fitting an electric waterpump (like this one) (http://www.daviescraig.com.au/Electric_Water_Pumps-content.aspx)in place of the engine driven one. It will give you a higher flow rate than when the engine is at low revs, and you can leave it and the fans running after you shut the engine down.
Thanks for that. I'll try it now its vanes have been cleaned and keep the website if that fails. I like the magnetic drive design, no seals to fail and stuff up a day's racing! I guess you just take off the mechanical pump and blank off the drive?

[I14]

hey man,

before you go too far on fixing up stock rads, they are borderline on a hot day if they are perfect and your ringing the nuts off them.

Fixing a radiator will prob cost you little less than buying a proper race radiator (top only) that will cure all issues. RB imports in aussie sell them for 475 AUD, usually they have them in stock. When i talked it through with them basically they found these to be the best option for there forumla 400 class in aussie head.

HRC did an oil cooler for them as well to keep them cool in Japanese F3 competition use. You can retrofit other bikes(cbr600f4 is common) oil coolers without tooo much hassle.

but again man 100+ or boil over is not really an issue if its only on dummy girds or when you make it back to the pits. If it doesn't overheat during the race alls good.
No it didn't overheat in the race so I think the cheapest fix is to fit a higher pressure rad cup to cope with it getting a little hot when back in the pits. With the motor turned off then you wouldn't think you could do any damage! Last resort a bigger Oz rad.

[koba]

No it didn't overheat in the race so I think the cheapest fix is to fit a higher pressure rad cup to cope with it getting a little hot when back in the pits. With the motor turned off then you wouldn't think you could do any damage! Last resort a bigger Oz rad.

I was working on a photo but havn't had a chance but I had a fan off a bike mouted on a stick and hooked up to a freshly charged 12volt battery when I was running a special that had an NSR radiator hooked to a KLR600.
It worked a treat on the dummy grid and after the race.

This was an exceptionally small radiator for the cooling requirements of the engine though, and even then it took a bit for it to boil over.

I find it hard to believe the standard NC30 radiators aren't up to the job if they are in good nick, on the hottest day of the year after a 20lap race maybe but do look over the whole thing carefully and make sure everything is all good.