Shouldn't be building up enough pressure to blow off mate. It's not a closed system so should drain out. So i'd go with head gasket failure or blockage leading to overheating.
maybe water pump failure.
-- Edited by Calum122 on Tuesday 28th of May 2013 09:57:39 PM
Found a small (hopefully) problem with my DTR. After I've been out a run for a wee while the rubber cap on the expansion bottle is under pressure and will eventually pop off if I continue riding. The coolant is getting from the radiator to the expansion bottle (water in expansion is same colour as coolant).
Not particularly sure where my problem lies, any suggestions?
Happened before and bike overheated, got it home an garaged and totally forgot about it until it happened again after a few rides. Bikes been running fine minus the overheating.
Whats the best way to check for the pump failure or blockage? I seen a few threads on the head gasket so will check those out also.
you will only see the water move after the thermostat has opened (hot as) buuuut if you see bubbles in there and its spillin out while its still cold then its pressure not heat expansion ,so is a quik test let us know dude i love lil probs like this ,hope this helps man
yep it will over heat if its the top seal,but if you only go 300 yards and its pressurized and starts leaking thats not the coolin system on its limits its combustion /cylinder pressure ,we've all had it when using cheap head gaskets ,then we got the knowledge of famo and havnt looked back lol
There's no apparent leakage, the water in the radiator just becomes diluted with the coolant already in the system (red). Water was vibrating when I had cap off and running for ten mins then became warm to touch not too hot though.
Don't think there's any oil in the radiator from what I've checked.
Positive its blowing off under pressure. Theres no sort of vent on the rubber plug to allow the pressure to relieve itself.
No but there should be two pipes connected go the bottlE. one from thw radiator and the other going into the frame on the dtr i think. on the re it just goes to the floor.
The only reason i can think of as to whh it would exert that sort of pressure is vaporising the coolant via a leaky head gasket.
let us know dude i love lil probs like this ,hope this helps man 
