My 2007 300 EXC doesnt seem keen on hanging on to its coolant...
It seems to overheat a bit to easily, normal riding is ok but a bit a gnarly hill climb and thats it steam all over the place and bugger all coolant left.
I suspected a knackered rad cap, so I replaced that.
The old one must have fukked cos as soon as it presurised it starting leaking all over the place.
Fixed the leaks, but it still seems to overheat and dump the lot.
well if you have a 1.8 bar cap on, and good quality fluid i'd say the next place to start looking is the thermostate and then the pump. daft question but the rads/engine has been bled of air?
no sense looking, all the 07 300s overheat, and you cant get a fan as the tank is to close to the rads on RHS..... rig a fan up as i suggested and 1.8 ca, and lay of the clutch and it will be OK
might not be relevant, but I has the same problems on my 530 exc, fitted a fan and better but not fixed, then I looked at the pipe that comes out of the bottom of the radiator and it had been squashed very oval in an "off" it was restricting the coolant flow, once quezzed carefully back into round and the rads could flow properly all good, so I would check your rads over carefully and also your rubber pipes in case they have collapsed, almost certainly sounds like you have either a blown head gasket or a blockage somewhere, it is was head gasket I would expect the coolant to end up in your gearbox oil, have you checked that? Any mayo?
So far:
Re-routed rad pipes so not squashed
Ditched thermostat
Cleaned all fins on the rads
Replaced rad cap
Filled with 50/50 halfords best anti freeze & water.
After it has boiled then cooled down, is the water still above the fins inside the radiator? Many people put too much coolant in the system and it boils off the excess then its OK. Should be just above the fins when cold.
You say the fins are clean but can you see clean through the radiators from one side to the other? They can look clean but not be when you look close. It makes a massive difference to the cooling, even if 25% is blocked to the air thats 25% less cooling, good for making tea but not good for motors.
I have just had the gasket blow between the engine casings on the clutch side, was leaking an pushed gasket out, this is on a pretty much brand new bike, my local dealer said he has sold a fair few of the gaskets so I would say it may be an issue, look for little leaks
Get waterless Coolant !! Made by Evans. £30 for 2 litres.
You dont need a fan or high bar rad cap. It boils at 180 degree & freezes at -40 !! Also it wont corrode the rad either.
Ive had it in my crf 280x & its in my 300 exc with Rekluse. I do a lap of Cown quarry & whip off the rad cap & nothing - no steam - or boil overs !!! STICK IT IN & FORGET ABOUT IT
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