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)
