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Just a quick request to confirm operation of the radiator fans. As the weather has been of a nicer state recently, the bikes running temperature has obviously increased a bit quicker in town. Am I correct in thinking that it is normal for only one fan to kick in as the temp increases into the mid 90's and as it gets to the upper 90's then the second fan will kick in?

If this is the case then all's good, if not, then where should I start looking.

Cheers

Ermm - no

Both fans should run together

Methinks one has stuffed fan motor although I would check the wiring as I've never heard of a motor failing - senders yes but not the motors

Both fans definitely work, I saw both running at the same time above 96 degrees, I was just curious though, as when it is between 92 - 95 only the right side spins up, and as it increases then the left side also kicks in.

I wasn't sure initially, mainly due to the fact I have the R&G crash bungs fitted, and the left side one squashes the fan motor into the back of the rad if you don't trim it down.

Maybe a bit of fouling still there

The fan circuit is very simple. Power to a thermo switch (which is what normally fails, or more accurately sticks), switch switches a relay, relay powers fans in parallel so if both aren't coming on together, there's still an issue there somewhere

Righto, a bit of further imagineering is required then.

Just run the bike up to operating temp and noticed the following:

94 degrees right hand fan kicks in, no voltage at left fan
97 degrees left hand fan also kicks in, both fans running
as temp drops again below 97 degrees, left fan shuts down
as temp drops further below 94 degrees, right fan shuts down.

I tried this with the crash bung fitted and removed, no clearance issues there. Both fans spin up freely with no excess freeplay or resistance. Both fans recording same resistance through them.

Output at relay is fine, and from what I can gather the voltage and resistance through the wires connecting the relay to the fans is fine.

I really don't want to be stripping down the harness and rebuilding it.

check the wiring, maybe someone moded it to run like this?

As long as it doesnt overheat, it shouldnt be a problem? It's running functionally, so all is well?

I wasn't sure if it was a 2 stage system or they both kicked in at once. They both work, and do the job so I will see how they get on.

Not a problem when the bike is out of town, being the fastest colour it cools down very easily

my both fans come on at 96-97 , but i read thes engines like running hot

This makes no sense whatsoever. If you look at the circuit diagram that are wired in parallel with each other - powered from the same relay. They MUST work together (unless someone has done something very odd with the wiring)

i agree ,

D-Rider wrote:This makes no sense whatsoever. If you look at the circuit diagram that are wired in parallel with each other - powered from the same relay. They MUST work together (unless someone has done something very odd with the wiring)

I have to agree with you, if it was in series, or it had a dual stage temp sender, then I would be happy to leave it at that, but after checking everything, I just can't fathom it out.

At some stage all the electrics will propably need removing due to the bodge job of the previous owners Hawk alarm, which I am still trying to remove. There's wires all over the place, and they have just been spliced and wrapped in electrical tape. NOT a professional job at all.

At the end of the day though, if the fans do their job, then it should be alright to crack on. I'll just bear it in mind should the temp start to get excessive.

Righto, went out and stripped all the connectors all the way through the bike, and got the bike out for a good run. BOTH fans are now kicking in at 96 degrees at the same time, switching off together and operating in parallel

I haven't got a clue what caused the series running, am happy now that it works as it should

That's a shame. Seemed a very good mod.

Glad it is sorted :)