G'day, WELDO ...... this relates to an '04 Z750, but should be around the same conditions. Cheers, Ron. The thermostat is a wax pellet type which opens or closes with coolant temperature changes. The
thermostat continuously changes its valve opening to keep the coolant temperature at the proper level.
When coolant temperature is 55°C (131°F) or more, the thermostat closes so that the coolant flow is
restricted through the air bleeder hole, causing the engine to warm up more quickly. When coolant
temperature is more than 58 ∼ 62°C (136 ∼ 144°F), the thermostat opens and the coolant flows.
When the coolant temperature goes up beyond 95 ∼ 101°C (203 ∼ 214°F), the radiator fan switch
conducts to operate the radiator fan. The radiator fan draws air through the radiator core when there
is not sufficient air flow such as at low speeds. This increases up the cooling action of the radiator.
When the coolant temperature goes down from the operation temperature by 3 ∼ 8°C (37 ∼ 46°F), the
fan switch opens and the radiator fan stops.
In this way, this system controls the engine temperature within narrow limits where the engine operates
most efficiently even if the engine load varies.
The system is pressurized by the radiator cap to suppress boiling and the resultant air bubbles
which can cause engine overheating. As the engine warms up, the coolant in the radiator and the
water jacket expands. The excess coolant flows through the radiator cap and hose to the reserve tank
to be stored there temporarily. Conversely, as the engine cools down, the coolant in the radiator and
the water jacket contracts, and the stored coolant flows back to the radiator from the reserve tank.
The radiator cap has two valves. One is a pressure valve which holds the pressure in the system
when the engine is running. When the pressure exceeds 93 ∼ 123 kPa (0.95 ∼ 1.25 kgf/cm², 14 ∼ 17.8
psi), the pressure valve opens and releases the pressure to the reserve tank. As soon as pressure
escapes, the valve closes, and keeps the pressure at 93 ∼ 123 kPa (0.95 ∼ 1.25 kgf/cm², 14 ∼ 17.8
psi). When the engine cools down, another small valve (vacuum valve) in the cap opens. As the
coolant cools, the coolant contracts to form a vacuum in the system. The vacuum valve opens and
allows the coolant from the reserve tank to enter the radiator.
I've spent over 40 years of my life riding bikes .... the rest of it, I wasted ..
If it's got wheels or tits, it's gonna give you trouble !
HCST #2
Team Black '09 ..... R.I.P. - 2011.
Back in Black....2011.
Mine runs 94-96 if Im amongst the Sydney traffic... Seen it hit 102 a couple of times on hot days, but the fan kicks in and keeps her steady. On the open road and hot days about 86-92. Dont stress mate all is good
I've spent over 40 years of my life riding bikes .... the rest of it, I wasted ..
If it's got wheels or tits, it's gonna give you trouble !
HCST #2
Team Black '09 ..... R.I.P. - 2011.
Back in Black....2011.
My 05 does the same on hot track days in Sydney as well. It pisses me off. You can see that our radiaotors are quite narrow and dont run the entire height of the frontal wheel area.
That is why I'm going to buy an 2nd hand cooler, probably from a GSXR 1000, an oil cooler and convert it to my 10R. This will give me maybe 20 to 30% more cooling efficiency, hopefully.
Other than that you would need to buy a proper race radiator which is in a lot of people's price range.
Or, get an 04-07 CBR1000 radiator ; they're about 40% bigger also, although they'll need a bit of cutting and shutting to fit (hoses in the wrong places, as is no doubt the mounting brackets)
The only down side is that they appear to be pretty fragile, so hard to come by second-hand and expensive when you do.
Cheers,
Brian
07 ZX10R track 09 ZX6R road/track 93 ZXR750 race 89 GPZ900 project Do not walk behind me, for I may not be leading
Do not walk in front of me, for I may not be following
Do not walk alongside me, for the path may be narrow
Just piss off and leave me alone
Well, I know you guys all put up with it and thats fine if you shorten your oil service intervals, but I'm going to increase the cooling capacity of my coolant by retro fitting a GSXR 1000 Oil cooler below my existing rad. It beats getting a deep core rad made and spending thousands.
You might think I'm mad, but I'd rather improve my cooling efficiency by 20% so the bike has a chance to shed heat when there is a bit of flow than nothing and just let it cook the oil.
These machines were made in a country that doesn't share the same climate as we do, so they make the machinery to a very fine limit.
They only thing saving your engines is the technology in your oil your using.
Anyway, I'll keep everyone posted on how it goes and whe I do fit it out I'm going to thrash the living shit out of my motor on the hottest day give you the details.
........ for the 750, as well. 
