I have seen lots of weird overheating issues,but this one has me boggled. Its a low miles stock 750 that has run like a champ for a couple races. The last race at barber it started leaking coolent(ww) out of the top of the rad cap and caused a lowside. Replaced the cap thinking it was bad and must have been. Well now after burping the system a couple times it still overflows out of the res hose. Head gasket? starts to spit at 220 and the bike has no fan. Is that just the overheating point?
If your not running fans, around 220* its getting hot and will prey start to spit coolant... if it has gotten hotter than that before, it is possible that the head is warped and the head gasket is leaking.
Sounds like a head gasket. No, it should not spit at 220. Sniff the coolant, does it smell like combustion? Generally if you have chronic leaking into the reservoir, something is pressurizing the coolant, and if it has run fine before, it is probably a head gasket leak.
yea we have burped the pump and re done the coolent 2 times just to be sure. About to install the fan and see what happens.. do head gaskets just blow? like 3000 miles on a stock motor?
smelled the coolant and didnt pick up anything abnormal. From cold it took it a while to get up to temp(parked)but once got up to 215+ i can hear the water boiling. Its not bubbling in the res while running,but it does slowly fill till it erupts @221~223deg.
If it is a track bike, the fan makes it run hotter. Fans are worthless over 30 mph. They just impede the flow. If you are riding it back into the pits and parking you should not have a problem.
Could be a bad thermostat. If it doesn't open up at the right temp the water may not start to cycle through the rad until after it's already reached boiling point.
You can ask your friendly quicky tune guys if they will run their engine analizer's sniffer probe over your open radiator, that will tell you right away if there are hydrocarbons swimming around with the coolant. The trick is finding a shop that will do it for you.
