Hey All, Got my NC Sorted a few months back, But i've had some serious cooling issues

Can't make any major journeys due to the bike overheating and pissing it's coolant all over my rear tyre out of the overflow, so i sorted myself out with an overflow bottle which i can drain & Cleaned out both radiators/Hoses and the heads :)

Problem is though, As soon as the system has built up pressure, The radiator cap opens and starts to fill the reservoir which just means i lose coolant out the system and the bike gets even hotter. As i understand the cap opens at 1.1 Bar, So i made myself an adapter for a pressure gage and stuck it in the hole for the temperature sender on my thermostat, Bike happily runs the pressure up to 1.1bar with the standard radiator cap on, which then opens and relieves the pressure and pisses water into my overflow bottle, after 5 minutes of running my overflow bottle was full.

I then sealed my radiator cap so it couldn't release the pressure, and the system built up to about 3 bar in about 2 minutes, at which time i figured i'd stop since i didn't want to make one of my hoses go pop

So, i'm just thinking the systems always going to just hit 1.1 Bar and throw all the coolant away, which makes the bike even hotter, Is there some sort of relief valve that will keep the pressure from opening the cap and keep my coolant in my bike rather than all over the road?

Any Suggestions?

This is driving me nuts, any help appreciated :)

Cheers, Nick

What temp is the gauge at when the cap opens? Are the radiators clear? (the bottom ones in particular gets blocked with crud) Do you have a fan on the lower rad, and if so, is it kicking in?

There is definately something wrong with your cooling system. It can only be a few things... maybe the thermostat is stuck closed and isn't letting coolant flow from the engine to the rads, or maybe for some reason the water pump isn't working. The pump runs off a shaft that runs through the oil pump and runs off of a chain that is driven from the transmission input shaft. Hopefully all of those components are working fine.

if its building up excess pressure, then head gasket maybe? Can u get to a local garage with a gas anylzer,if so get them to check if theres any exhaust fumes in there

wills123 wrote:if its building up excess pressure, then head gasket maybe? Can u get to a local garage with a gas anylzer,if so get them to check if theres any exhaust fumes in there

Or you can check the oil for any water, which turns the oil white. You should also see some white smoke coming from the exhaust.

Throw the stat in a pain of boiling water and see what happens.

Check the water pumps still there and working ok.. (the blades of mine dropped out when i took the cover off)

Have you bled it properly?

Run it on the side-stand without the cap, when its at operating temp snap the throttle to 5k 3 - 5 times, kill it and allow to cool, top up.

I've replaced the head gaskets with new ones, I know they're fine.
Recently changed the oil and the old stuff hadn't emulsified so no water there.
Currently running with no thermostat, and i know the pumps running fine since i've had a few mouthfulls of antifreeze

I think the problem is related so the water not returning to the pump through the radiators properly, as i've just stuck a zxr750 rad on it and the system was fine. Whilst it has the standard radiators on you can watch the water backlog and then drop down to the pump.

Hmmm, I'm thinking of trying the speedfight mod, Anyone had much luck with this?

Cheers

Speedfight mod is not worth it. the rads look similar but it carries so much less volume that I would not bother.

Sounds like your rads are scummed up bigtime - there is probably a high pressure hosing dying to get into the rads and swil them out!

I had my lower one recored for £165 and it is bob on...

agreed it sounds like the pressure is building due to blockage and its being squeezed in through to small an opening and you've confirmed its the rad by changing it.

Might be looking into what a recon unit is now compared to having it cored back out though