I've got some of geoffs rads on my bike and they work great, only problem is the bike loves over-heating when stuck in traffic for longer than 10 minutes, and I mean the temp gauge is well into and sometimes past the red on the far side.

The only reasons for this I can see is, the waterways in the engine are still full of shit even after a rad flush a few months ago or the rad cap pressure isn't sufficient.

I'm currently running Geoff's rads with a 1.1 Bar cap, samco hoses, standard fan with a manual switch and standard water pump which is in good condition (or was when I checked after doing the rad flush).

So would a higher pressure rad cap be the first thing to look at and try out, or do I need to be investigating elsewhere?

bikemonkey wrote:I've got some of geoffs rads on my bike and they work great, only problem is the bike loves over-heating when stuck in traffic for longer than 10 minutes, and I mean the temp gauge is well into and sometimes past the red on the far side.

The only reasons for this I can see is, the waterways in the engine are still full of shit even after a rad flush a few months ago or the rad cap pressure isn't sufficient.

I'm currently running Geoff's rads with a 1.1 Bar cap, samco hoses, standard fan with a manual switch and standard water pump which is in good condition (or was when I checked after doing the rad flush).

So would a higher pressure rad cap be the first thing to look at and try out, or do I need to be investigating elsewhere?

Really not the way to go.

The stock NC30 rads and cap are normally fine.

The fan is only of use at idle when not moving to keep air flowing.

Some things to check in approximate order of easyness..

1. Your fan is the wired up the right way around? (only an issue if somebodys been messign with teh plugs) (it sucks air in, it doest blow)
2. You don't have any air-locks in the system. (bleed it properly)
3. The water pump is working properly. (get the cover off and check the impeller blades and that it spins when you press the starter.)
4. head-gasket failure, putting hot gasses into the water system causing overheat.

Okay I can eliminate two things there, I know the impeller is working fine (unless it has broke in the last 3 months) and I know the system is bled properly.

Your probably right about the fan wiring as I didn't really check it properly when I put it back together, shall get onto it on my next day off.

Have a check of the fan but it only helps when you are idling.

Perhaps there is still come gunge in the system, was it badly corroded , dirty before you refilled it?

How did you bleed the coolant_

I'll get to the fan on tuesday (I work all weekend every weekend, it sucks).

As for gunge, when I did the rad flush not a fat lot of gunge or limescale came out but the coolant that I drained from it beforehand was orange like rust. I've changed the rads and hoses since the flush.

I bled the system with the rad cap off, idling and gently revving the bike, squeezing hoses etc until no more bubbles came out.

Right so I'm at the fan wiring and yes it is wired wrong, the fans blowing the air back through the rad, not helpful obviously.

So while I'm at it I thought I'd tidy up the mess of wiring the previous owner has put on for a manual switch.

They ran wiring from the battery to the fan and switch and just taped up the original connector.

Now am I right in saying that I can plug back in the original connector and ground the sensor wire through the switch to have the same result but a tidier loom/wiring bit?

Answered my own question, yes I can.

Now to permanently add the switch then test it in traffic

Did you check the thermostat to see if it was operating correctly?

Yeah I replaced that a couple of months ago, it was only opening 3mm.

Tested yesterday, did not move further than the middle of 90 and red.

Problem solved