Ive had some Chinese rads fitted on my nc30 for a good few months now, now the weathers getting a bit warmer ive had a problem come up 2 or 3 times.

First time it was a warm day and i wasnt riding economically.. pulled over to check directions and i had coolant pissing out the rear reservoir bleeder.

Other 2 times it was a warm day and was snailing around a little in traffic.

At the moment ive kept a big bottle of water/antifreeze in my bag; wait a good while for the bike to cool a little and fill it back up. Also been using my gears a bit better

The description for a the radiators said they have more capacity than stock ones; is it possible theres not enough room in the rear reservoir to hold the required hot coolant when its pushed back? ( Just a thought, im not too mechanically minded )


Some feedback would be really helpful

Keir

did you measure how much juice you put in? did you bleed the system fully, you may have an airlock, or your pump could be shagged

At the end of the day it's a reservoir! The HRC bottles fitted have no coolant in them until the coolant expands and therefore overflows into the reservoir. Depending on the coolant you have will also raise the point in which it boils/expands/overflows. Also sitting idleing after a run or commuting in slow traffic don't help as the rads need air to cool them or the fan. So open road riding not sat behind someone closely is the way forward.

Porndog: I haven't no but depending on how long I havent realised for ( not long these times ) roughly 250 lost each time ?
My fan kicks in when its over 90 which I don't think is early enough, is there a way to change that for a start?

could be the rad cap is not sealing proper, correct me if im wrong but if its not sealing then it wont pressurise the system and the coolant will boil quicker,

Deviant400 wrote:could be the rad cap is not sealing proper, correct me if im wrong but if its not sealing then it wont pressurise the system and the coolant will boil quicker,

True, but it's also suppose to regulate pressure, so when the coolant expands due to heat, it allows it into the resevoir.

Are you overfilling the resevoir?
You mention coolant overheating... but you havent said your temp gauge actually shows hot... All the way right hot.

Sounds like it is too full to me - leave it to piss out and then let it cool all the way down - if there is anything left in the reservoir then leave it alone.

If nothing at all left in the reservoir then check the rads - if they are also low I'd suspect a knackered cap that is allowing it the boil prematurely and losing the fluid.

Did you get a new pressure cap with the rads? If not i would definitely fit a new rad cap first. My old one wasnt holding the pressure and was letting water past before it was anything like fully hot.
Dave

So long as your coolant bottle isn't over-filled (fill it upto the MAX) mark then it shouldn't expand so much water.

Firstly is there an air-lock in your radiators?

Fill the bike with the sidestand down, leave the rad-cap off and idle upto temp, snap the throttle to 5000rpm 3 or 4 times and then turn off the engine and allow to cool.

While it's cooling squeeze the lower rad hoses a few times to help purge any air.

After it's fully cooled fill the rad to the very top and replace the cap.

Is it a new cap or the old one? It might not be sitting right, if it's a chinese cap i'd ditch it for a proper Honda one, if it doesnt' hold pressure it'll be letting hot fluid escape.

The rad fan coming on at 90+ is fine.

Ive not filled the coolant from the back always the front, i dont think the temp gauge has not gone ( or not far ) past the 90 mark, never enough for the fan to come on anyway.

I can see theres a lower and upper level on the rear reservoir, but when the bikes cold where should both the rads and rear reservoir be filled to?

I did get a new cap with the rads, my dad said the original one would do a better job, ill dig around for the one that came with the new rads and try it out aswell.

Extra info: the coolant hasnt yet leaked from the rad cap, only the bleeder in the rear reservoir