coolant leaking from rad cap

copson · Post by **copson** » 05 Jun 2005, 11:02

please can someone help I've bought a crm mk2 and have used it for about 2wks I've noticed that when I leave it ticking over when stationary after about 5min the coolant starts boiling up through the rad cap. I'm not sure where to start looking .do they have a thermestat or is it the head gasket there is plenty of compresion and normally starts after 2-3 kicks any ideas anyone?

CRMR · Post by **CRMR** » 05 Jun 2005, 17:07

Hi mate , There is a thermostat , Its located on the top of the head ,, see fig 7 here http://www.crm250.com/images/diagrams/m ... s/001.html . So , A quick test for this would be to remove stat from bike and pop it i some boiling water ,, You should see it open in hot and in cold it should be closed ??\"It could be opening too soon or jammed open allowing things to boil up.Or.It could be a simple case of you rad cap lost its balls and is opening to easily..What colour is the top dot in the rad cap ,,This denotes the pressure it should release at ,,Check somewhere in the forums for the values

thermostat closes at 62 deg c
thermostat opens at 72 deg c

also check your waters pumps running ok ,

copson · Post by **copson** » 06 Jun 2005, 14:40

cheers for reply, have checked water pump and is working fine. took bike out sunday afternoon for about an hour ran greaqt didn,t overheat at all. parked bike back in garage and left running started to overheat after about 10min could it be that with it being in the garage ther is no air flow to cool the rads and that is causing problem or do you think its running a bit lean causing it to run to hot any idea what the mixture screw should be set at?

CRMR · Post by **CRMR** » 06 Jun 2005, 15:59

Yes , The air screw setting should be 1-1/4 turns out ....You should be able to tell if its running rich by the colour of the spark plug..