have you chcked the water pump fins and the radiator for cold spots when running?

sensors can be faulty but check the obvious too, plenty of cooling systems are partially blocked / coolant pumps knackered.

bubbling and spitting doesnt sound a good sign though if you've bled it, ive had this from coolant flash-boiling in the engine due to lack of circulation (fried water pump) and other time from partially blcoked radiator and stuck thermostats.

magg wrote: So fan switch thinks H is 90 degrees or temp gauge thinks 90 degrees is H. Someone must be wrong. .

This would be true if the sensors were located in the same place. However, the fan switch is on the core of the rad and the temperature probe is by the stat.

If theres a lack of circulation / blockage then hot water from the engine will reach the stat housing first as its in the block and report a high temp. Without proper cirulation it can take a while for water to move around the rad and trip the fan switch.

My CBR250 had the same issue, gauge would be running up near the H mark but fan wouldnt cut in until it was just getting over H, I assumed it was faulty sensor and ordered a new one, same thing. pulled water pump flushed everything.

replaced a lot of stuff and chased in circles, flused engine with high pressure hose and rad too, turned out the rad was partially blocked.. the middle section of the core remained cold, this was close to the fan switch too.

New rad and runs in the lower 1/3 of the gauge now.

cbrdude wrote:Cheers magg.
Job for another day. Think I'll stick to riding my 'Blade. No dramas with that one.

Your nc will so much more rewarding than the blade should you get it running right!!

Two things you did not mention in as part of your cooling system rebuild were the thermostat and water pump.

Yakama wrote:

cbrdude wrote:Cheers magg.
Job for another day. Think I'll stick to riding my 'Blade. No dramas with that one.

Your nc will so much more rewarding than the blade should you get it running right!!

I prefer my 954 in pretty much every way to the nc30...

In which case, time to ditch the nc30. After getting my NC35 I kept my '98 R1 for 8 months...in case. I never rode it. Sold it to let someone else enjoy her.

manicguitarist wrote:In which case, time to ditch the nc30. After getting my NC35 I kept my '98 R1 for 8 months...in case. I never rode it. Sold it to let someone else enjoy her.

Thats your choice.

Just becuause I think the cbr is a better sports bike doesn't mean I don't enjoy riding other bikes too.

I also have some 60s scooters as well as a 2010 Aprillia 200 scooter. While the Aprillia is better than the 60s bikes I still enjoy riding the old ones.

A lot of urban legend about how good the old 400s are is still around though, and sure that did hold up against most of the 90s larger bikes which were heavier and slower turning.

Comparing them side by side, to me the cbr beats the 30 on most if not all points, its lighter, faster, handles better and feels just as tiny and flickable, with the added bonus of more comfortable riding position.

Just like the Aprillia I have compared to riding some of my other bikes.

So yeah if I was racing one i'd be on the CBR but since the majority of my riding is commuting with very little for pleasure then having the fastest / lightest or whatever doesn't really matter.

I'm in a position where I can choose from several bikes depending on how I feel, it's not like im holding onto the last ever one and hate it out of some spite or something.

If I do cut bikes down though the nc would go before the cbr.

Fair point.
Put the NC in a plinth in the front room!
:)