Newbie with non-working fan

[Jules]

Hi to you all from hot Japan. Very glad to have found this site and hope you can help. I recently bought a '91 Bandit 250 in average condition. Goes OK; some carb issues which are now mostly fixed.

But, my fan doesn't appear to work. It's getting hot here now, about 28.C every day and still no sign of the fan in the non-high speed mostly suburban riding I do. When does your fan usually cut in?

Any quick way to check the fan works? Is there a fuse?(If so where is it,I can't find one?) Is the thermo-switch liable to fail? I guess I should run a wire direct from the battery to the fan as a first step.

All advice, tips greatly appreciated. Thanks

[erik]

check to make sure the fan is free to turn. when I got my b4 the fan wasn't working, a stone had got stuck in the shroud which stopped the fan from turning, also the fan motor had corroded. And the thermo switch was stuffed! I'm not sure what caused what though.
Anyway, if the fan turns freely, you should be able to test if it works by bypassing the thermo switch, just unplug the thermo switch and connect the two wires that plugged into it together and the fan should go (if the bike is turned on).

[Jules]

Hi Erik

Many thanks for that, I'll have a go this w/e (once I've found a 20mm spanner.....) and let you know.

[erik]

what do you need the 20mm spanner for? if it's for removing the thermo switch, you shouldn't need to (unless it's stuffed or you want to test it in a pot on the stove).

[Jules]

what do you need the 20mm spanner for? if it's for removing the thermo switch, you shouldn't need to (unless it's stuffed or you want to test it in a pot on the stove).

But I do want to test it in a pot !

[Jules]

OK, connected fan leads together and fan works fine, so removed the thermoswitch and will order replacement. thanks for the tip Erik.

[erik]

glad it helped 

Have you tested what temperature the thermoswitch turns on at? It could be its just not getting hot enough to need the fan?

I've got to test the thermoswitch in my bike. The original was stuffed when I got the bike so I replaced it with a similar temperature switch from an auto parts shop but either my bike isn't getting hot enough, or the switch has died again because the fan doesn't ever come on.

[Jules]

[quote author=erik link=topic=11097.msg89041#msg89041 date=1215860894

Have you tested what temperature the thermoswitch turns on at? It could be its just not getting hot enough to need the fan?

[/quote]

No, I haven't done that yet, but there lies the rub. When DOES the fan come on? I've ridden it hard 2-3 kms up the steep hill behind my place just to get it to come on, but nothing. I reckon I should take it for a thrash on the expressway, then come back on local traffic filled roads; if it doesn't come on then, I'll assume the thing isn't actually working. It's 33.C here right now.

[camarobandito]

Hi Jules, The thermo switch for the fan comes on at 243.f (117.c) ant it should shut off at 230.f  (110.c)I dont think you are getting the bike hot enough to trigger the fan. Mine has only turned on twice this year and we have had hot weather like yours. Were you going up that 2-3 km hill fast? You might try to do it slower so the engine has to work harder and wont have the air flow from the speed or even try covering the front of the radiator with something(piece of cardboard should do). If i let mine idle for 15 or 20 minutes the fan will kick on. But keep in mind I have the 400 not the 250 but that shouldnt really make a difference. Hope that helps and ride safe!

[Banditmax]

Leave it on fast idle for 20 minutes the fan might kick in then if its going to.

[andrewsw]

my B4 fan only comes on in heavy urban stop and go traffic on very hot days (like 95+ F). I just love to be sitting behind a bus, sweating my ass off when that fan kicks on and bathes me a beautiful wash of nice hot air... 

And the bike needs to be fully warmed up going into that situation for it to start kicking on.

[erik]

Hi Jules, The thermo switch for the fan comes on at 243.f (117.c) ant it should shut off at 230.f  (110.c)I

You're getting confused with the warning light thermo switch. The b4 manual says the cooling fan switch should go from off to on at 95°C and on to off at 88°C when you test it in a pot of oil.
The switch should have the temperature it turns on at in °C stamped on the side, I think. The one in my b4 was a bit different from what the manual said, it has 98°C on the side. When I tested it, it didn't turn on until about 106-114°C and off at 94-87°C so I assumed it was faulty and replaced it with one from a car shop
The one from the car shop turned on at 93-97°C and off at 87-88°C.

I want to test it again though because the fan never comes on.

The old warning light switch was stuffed too, first time I tested it it didn't fully turn on, only dropped to 500 Ohm at 130°C first time I tested it, then the second time it only dropped to about 11kOhm at 149°C.
The new warning light switch I put it turned on at 109-117°C and off at 105-107°C (lower than the manual says it should, but that's most suitable switch I could find without getting a genuine part).
I haven't seen the warning light turn when the bike's been hot though, so want to test the switches again. Maybe the bike just doesn't get hot enough.

Keep in mind I'm talking about the bandit 400.

[bandit250]

I was out in Chiba today (Japan) for 45mins in very heavy traffic. The fan didn't come on & it only comes on after riding the highway and then joining congested roads.

Letting it idle for 20mins does bring it on as that is how I tested mine after fitting the new thermo switch.

[Jules]

Thanks guys! Great response which has made me come to the conclusion to..........do nothing for the moment except ride it in more heavy traffic and at some point do the 20 minute idle. I might even bypass the thermoswitch and fit a simple on/off switch; kill a few birds with one stone.

[daveberry]

hi just thought id let ya know if ya give a thermo switch quite a bit of heat with a blow torch they sometimes kick back into life.