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Coolant system performance and mods

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liverpool_f_
the 900
the 900

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Coolant system performance and mods

Post by liverpool_f_ on Wed 03 Jun 2015, 1:11 pm

Hello all,

A couple of different related things. I was wondering if anyone out there could let me know how long it takes for their bike to warm from start up to reaching the lower point of the temp gauge. I know these bikes run cool typically but mine takes over 10 minutes to get to the minimum mark which is making me think the thermostat is stuck open all the time. I went for a ride with my buddy and we started our bikes at the same time. His KTM 950 had overheated and he had to switch it off before I even got warm enough to pull away!

Secondly, my bike has a manual switch for the fan instead of the thermostatic one which I quite like but I want to put the thermostat back again and have both. My bike was bodged together a bit at low cost as a hack but now I like it too much now and I want to get everything back to spec. I bought a new thermostatic switch as that was presumably the cause of the fan not working before the manual switch was installed. Does anyone know where I should wire it to with out having to get the loom for it. I would rather just solder the connection if that is viable.

Any help is as always muchly appreciated!
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ashcroc
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Re: Coolant system performance and mods

Post by ashcroc on Wed 03 Jun 2015, 2:13 pm

Warm up time sounds about right from my experience. Like you said, these bikes run cool. I tend to ride pretty much from the turn of the key as waiting 10-15 mins isn't really an option most of the time. I just don't boot it until it's warm.

Most of the time when a manual fan switch has been installed it's an overreaction after the fans earth has decayed or panic about where it naturally cuts in & out when stuck in traffic. I'd be surprised if someone's gone to the trouble of removing the original loom wires for the thermostic switch but if they have then running the manual & thermostic switch in parallel should work.

There's a download for the haynes manual here with the wiring diagram near the back if you haven't got a copy already.
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ceejay
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Location : Bournemouth

Re: Coolant system performance and mods

Post by ceejay on Wed 03 Jun 2015, 3:52 pm

Warm up time sounds similar to mine also - to me it sounds like your friends KTM is the one with the problem ; )

I don't ride my bike daily but when I do it tends to be big miles so can normally afford to let it warm up a bit or I'll turn the key whilst I mess about with gloves/jacket/helmet. You often hear/read that most engine wear is done when the engine is cold but then again I'm pretty sure the majority of car/bike owners ride from the turn of they key and still get plenty of miles out of their machines - especially the ones who keep the revs down until it's warm I'd imagine.

I don't have much to compare it to but my crappy Fiesta takes a similar time to get up to temperature on a cold start!
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peatrich
Rossi
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Location : Sheffield

Re: Coolant system performance and mods

Post by peatrich on Thu 04 Jun 2015, 11:51 am

I checked mine to see if the fan actually works because I'd never heard or seen it turning in the last couple of months. Standing ticking over in the drive it took all of 20 minutes to spin up!
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liverpool_f_
the 900
the 900

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Re: Coolant system performance and mods

Post by liverpool_f_ on Thu 04 Jun 2015, 11:56 am

Excellent. No need to worry about my thermostat then. Does anyone know if the thermostatic fan switch just wires straight to the fan? On the wiring diagram it does but some real world knowledge would be awesome.
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eternally_troubled
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Re: Coolant system performance and mods

Post by eternally_troubled on Thu 04 Jun 2015, 12:52 pm

The fan thermo-switch is the one in the radiator.

When it gets hot it shorts its inside contact (the one the wire is connected to) to the outside mounting thread. The thread is screwed into the radiator and the radiator should be grounded by a wire. So, if everything is working, when the thermo-switch gets hot it grounds the wire attached to it, which switches the fan on.

The most common reason for this failing is a bad ground connection to the radiator. This is often caused by the grounding wire connection point (at the top of the radiator) becoming corroded. So start by cleaning that up and measuring the resistance of the radiator to ground/battery negative (should be very low or zero on the meter).

You switch should be wired up so that when you switch it 'on', it provides a ground to the wire that connects to the thermo-switch in addition to the wiring that is already there, in this way it will over-ride the thermo-switch (so you can switch the fan on at will), but the system will still operate normally with the switch in the 'off' position.

Hope that helps, any questions just ask.

BTW - I would not bother in 'warming my bike up' too much, it is not really necessary with a CB500 unless you are planning full-throttle rolling burnouts from the off. The CB500 is much more proof against 'cold running' than, say, a water-cooled two stroke would be (which IME must be warmed up before any use!).
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liverpool_f_
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Re: Coolant system performance and mods

Post by liverpool_f_ on Sat 06 Jun 2015, 8:51 am

Cheers Eternally Troubled,

There is always someone with the correct info on this site!
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stormbringer
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Re: Coolant system performance and mods

Post by stormbringer on Mon 08 Jun 2015, 7:05 am

@liverpool_f_ wrote:the thermostat is stuck open all the time.

Worth checking. My local mechanic boils the thermostat valve as part of routine maintenance. Mine was off target, so I've got a new one fitted, opening at the correct temperature.

On 'warming up the bike': No, I don't do that either. For two reasons.

  • At tickover, oil pressure isn't as high as otherwise, I'm told. Obviously, this means less lubrication and less cooling of pistons. Putting the engine somewhere in the lower end of its operating rev-range should take care of the oil pressure issue, and not loading it when cold should take care of the wear issue. This makes sense to me, so I ride right after firing up the engine. Gently for the first couple of miles.
  • My neighbours would hate me for warming up engine in the driveway at 5:30 in the morning Smile
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ceejay
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Re: Coolant system performance and mods

Post by ceejay on Mon 08 Jun 2015, 10:02 am

 Mine was off target, so I've got a new one fitted, opening at the correct temperature.

Did you notice any difference in the time it takes for the engine temperature to increase after this?
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Pugzilla
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Re: Coolant system performance and mods

Post by Pugzilla on Wed 10 Jun 2015, 4:27 pm

I've had my CB500 for nearly 2 years and I can't ever remember hearing the fan turn on. Is that normal?

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Re: Coolant system performance and mods

Post by Guest on Wed 10 Jun 2015, 5:12 pm

After a ride on a warm summer day the fan turns on rarely but if it does then it's not for long ( minute or less) at lights or when getting back to the garage. Also slow inner-city riding on a warmish day may actuate the fan for a brief moment. Note that the coolant was recently renewed after a cooling-system treatment that didn't hardly needed doing in the first place. A quick fan test can be done by connecting the wire that goes to the thermostat on the radiator to earth (radiator itself for example), fan should turn!
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alvamiga
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Re: Coolant system performance and mods

Post by alvamiga on Thu 11 Jun 2015, 9:14 am

The only times I've noticed mine coming on was stopped in traffic on a warm or hot day. Even then, it's usually only for a manner of seconds. Can't imagine I'd notice it at 70, even if it did come on though! Smile
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ceejay
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Location : Bournemouth

Re: Coolant system performance and mods

Post by ceejay on Thu 11 Jun 2015, 10:24 am

I've had my CB500 for nearly 2 years and I can't ever remember hearing the fan turn on. Is that normal?

I think it's possible if you don't ride in a city as the only time I ever hear mine come on is when I'm stop starting in the middle of London or somewhere like that.  When you get up a bit of speed the cooling seems pretty effective, I sometimes notice the needle drop when I get on the motorway even on a hot day. That said it might be worth checking the circuit for peace of mind!

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