Hi All,

Just got back from a thoroughly enjoyable trackday with No Limits at Val De Vienne in France. The weather was scorching, 30 - 35'c both days with no wind. Bike has a standard engine, race bodywork, a new aftermarket lower rad, with original top rad. No fan (and unfortunately no temp gauge - its on my list of to do's) and I've also removed the thermostat. The top rad has seen better days, a few bent fins.

Bike was running faultlessly until towards the end of the first day, when as I came into the garage following a 20 minute session she overheated a little. I let her cool, added some more water and then bled her without the rad cap, squeezing the hoses etc.

Warmed her up and all seemed fine, went and did the last session of the day, no problems.

Second day, went out and did the first session and when I came in to the garages and turned the engine off, again she overheated (bubbling water coming out of the top of the overflow bottle). I gave her a good few hours to cool, took off the bodywork etc and had a good look around to see if there were any obvious leaks etc and could find nothing untoward. I gave her another thorough bleeding, but noticed the rad cap mount had seen better days and questioned whether this could be the root cause (although wouldnt the boiling water etc also come out of the rad cap)? Topped everything up, warmed her up and did the first session after lunch.

Unfortunately, again once I was in the garage the bubbling had started. I let her idle on the stands for a while to see whether this would help, but it didnt. It didnt overheat straight away, but after a minute or so did. So I decided to park it up for the remainder of the trip before I either caused any more damage, or damaged it permanently. There was no noticeable loss of power when out on track, and it did only start to dump the water once the bike was swtiched off/idled in the garage.

I'm just trying to get a list of basics to check, and came up with the following. Please chip in with any other hints/tips/advice;

1) New Rad Cap
2) Pressue test rad
3) Check water pump
4) Head Gasket gone?

Failing this, I may replace the top rad anyway and possibly even check the hoses for gunk build up, and replace where necessary.

Here is a pic of the bike working (and not)

yep my first thought would be on the rad cap.

Why run it with no fan ?

Old Painless wrote:Why run it with no fan ?

No fan mounts on the lower race rad mate.

But there is a fan on the top rad ?

If your flying round the track passive cooling should do the trick and when idling after/before riding out of the pit the fan on the top rad should keep it cool.

Maybe mount a temporary thermostat ?

Old Painless wrote:But there is a fan on the top rad ?

If your flying round the track passive cooling should do the trick and when idling after/before riding out of the pit the fan on the top rad should keep it cool.

Maybe mount a temporary thermostat ?

The NC30 has 2 rads.. the fan is on the bottom one as standard.

Would you have more pictures of your bike please as it looks very nice.

In hot weather my track nc30 usually creeps up in temp every session.

Drain your cooling system (bolt on the water pump cover), bolt it back up, fill your cooling system and dump the water again. Do it for as many times as you need to before you get only clear water out - it can take quite a few radiator fills to do this.

Your symptoms are pretty normal, just make sure you get all the radiator gunk out!

I have run many days at 30-40c with no issues. I have the thermostat, no fan, and Water Wetter. WW is non glycol, no glycol allowed at miller, and runs cooler than water. The only time I have seen over 90 on the temp gauge is when I over reved alot. Changed gearing, all is good.

For summerweather and racing a vfr/rvf take bigger rads.
















Michael