Overheating in slow moving traffic?

[Falco]

The bike is a CB500s (first bike I've had that wasn't air cooled, in summer).

Ended up leaving the lab a bit late today and got snarled up in rush hour traffic. 12 miles of filtering through solid traffic later I noticed the temp gauge on the bike was the highest I have ever seen it go (over half-way). Is this normal on a hot day in heavy traffic?
The bike normally sits at the 1st line on the guage all the time, but I've only had the bike since February so I have no idea how it acts in warmer temperatures. Once above 25/30 the temp dropped no problem. Is this to be expected in hot weather and heavy traffic or should I start check the fan/thermostat/other bits of the cooling system?

PS the coolant was flushed and replaced about 2 weeks after I got it.
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I tell you what, mathematically, I'm having it

[Rogerborg]

[Nobby the Bastard]

Sounds like the thermostat has been removed and so it's running artificially low all the time.

Did the fan come on?
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[ackack]

Only worry when it's in the red.
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"fli hi mi angle"

[RhynoCZ]

[Falco]

[RhynoCZ]

There are no bleed screws, as far as I know.

The thermostat does not turn the fan on. Thermostat opens/closes the ''long'' cooling circuit. Once the coolant is warm enough it opens and lets the coolant go through the radiator. If, for some reason, the temp drops, it reduces the flow to/through the radiator, to keep the engine (the metal bits) as close to the ideal operational temperature as possible.

Being familiar with the 90's CB500, these bikes run very cool all the time. So the fan should kick in only when it really gets hot. To check that, just ride it, get it hot and then rev it a bit when stationary to see, when the fan kicks in. IF the fan kicks in and cools the engine down, then you have nothing to worry about. From my memory, the needle of the temp gauge was always below the 1/2 of the OK range (the range between the Cold and Hot range).

EDIT: This answers your question: When should the fan kick in? - https://youtu.be/DImqWE75KIM?t=8s
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[Nobby the Bastard]

The fan should come on before the needle gets to the end of the guage.

if the needle doesn't get to the red / temp warning light doesm't come on, its not overheating.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[Kawasaki Jimbo]

I took the R1 on my first ever charity run to Addenbrooke's Hospital in Cambridge a couple of years ago, in December. I imagined we'd all roar up to and across the city like the Red Arrows but in fact we chugged along at 25mph with frequent stops. Pretty dull to be honest. The bike ran quite hot but there were no ill effects. I'm saying normal.

[RhynoCZ]

[Falco]

[Falco]

[RhynoCZ]

Definitely check the fan functionality. It's always better to be safe than sorry.
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[ackack]

[Teflon-Mike]

Remember there are TWO 'thermostats';
1/ a thermostat 'valve', which 'closes' to stop water circulating through the radiator when the cylinder is cold, and opens, as engine warms, to let the heat out, through the rad.
2/ A thermostat 'switch' most often in the radiator, rather than the head, which turns 'on' the fan, when the water in the rad is too hot, presuming it's not getting enough air-flow for the rad to do it's job.

THEN there's the temp-gauge 'sender', usually in the head or block, that changes resistance to make needle on the dash go up or down, depending how hot the block is.

Taking signal from separate sensors, in different places, it's not uncommon for the fan to kick in at apparently different temperature readings on the gauge, though should be fairly consistent.

Personally, I wouldn't pay too much heed of the temp-guage; it's not all that relevant to anything, and if it goes into the red, what are you going to do about it anyway? I'd be more concerned that the fan does, first work, and second does kick in, on the thermostat-switch....

I do know dispatcher's who would actually fit over-ride switches in parallel to the rad-switch, to manually turn the fan on 'early' when grinding through city traffic which I suppose may be of some worth if you do a lot of city snarl.... but otherwise mention, as the CB500 was a bike common with the dispatch brigade, and fan wiring 'may' have been bodgerised, in a similar way.

But, other than checking the fan works, by-passing rad-switch, and then trying to get the temp needle into the red, in 'controlled' conditions... like letting the thing idle for a while on the stand, after a good run, to see if it does go up and come on, when there's no air-flow.. I'd not really bother about it... far more important stuff to keep an eye on road-side than fret about a dial on the dash! If it gets hot enough to start 'fluffing' when you open the throttle, or missing and pinking, or chucking steam out the overflow vent... THEN I would start to worry! Otherwise, I'd rather have a bike with a blown head-gasket, than be SMIDY'd by a twit I failed to spot, trying to work out what the dial was doing, trying to listen if the fan kicked in!
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My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'

[Chris45]

[Pete.]

[sl121011]

Could be worth checking the wiring from the fan itself. IIRC, one wire from my old CB500 fan should have been connected to the radiator or somewhere very close to it (tucked away and not easy to see). Of course, that had long since corroded, was no longer connected and therefore the circuit was never complete... ...and the fan never came on!
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Current - MT-03, CD200. Gone - CB500

[MCN]

Wash the radiator fins, external blockage will prevent air getting to the hot parts of the radiator to take the heat away.
Simply job to try before ripping the beast to bits.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[ADSrox0r]

Said it before and I'll harp on about it again; try sitting on a 6th gen VFR in slow moving traffic, then you know what hot is about.

As already alluded to though; if the fan kicks in at the right temp and gets it back down to book spec...... meh. Nothing to fret about, she's meant to work that way.
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Current bikes: '08 VFR 800 VTEC(yo) , '07 ZZR1400 Winter hack: '95 Aprilia 650 Pegaso Currently lusting after: RC30