I have a CBR F3 and it keeps overheating and spitting fluid out of the overflow tube. Once the bike starts to overheat the overflow reserve starts bubling and fills all the way to the top and starts draining coolant out of the overflow tube. I replaced the thermastat, and checked the fan. Both are working fine. I thought maybe it was my water pump. I dont know what else to do.

 

Hope this helps .............. F3 manual

 

yo mang...do a pressure check.

 

If there's a small hole somewhere (or even a bad radiator cap) then the system cannot pressurize and the coolant will boil when it hits 212 degrees. Once it starts to boil then it cannot cool the engine and the problem gets even worse.

I'd check all the lines for leaks. You should check the water pump too. Pull off a hose and run the engine. If the coolant isn't flowing out then the pump's probably bad.

 

I agree. If the bike is otherwise running fine then check for leaks and that the water pump is working.

 

Thanks guys, I took off the rad cap and started it and gave it a couple shots. its seem to be alright now. I think i had air pockets in there. I know it isnt leaking coolant fom anywhere else cause i have all the fairings off and i looked over the whole bike when it was running, no coolant coming from anywhere else. I didnt ride it yet but i let run for a while and it didnt overheat or leak coolant so i think its alright. hopefully.

If starts to do it again i'll check the waterpump. I just wasnt sure how to check the pump to see if is was working. Thanks for all the help!

 

That's possible too. After flushing the coolant on my Mazda I have to spray water into the hose that goes back into the engine in order for the coolant to start flowing again. Kinda like bleeding the system.