7 replies to this topic

[TheDodge]

Hi,

I have a Gas Gas TXT 02 edition 250 and i could do with some help working out why the fan won't run.

Have not had an issue with it before but today i noticed after 10 mins riding some coolant was coming from the overpressure drain pipe and the fan wasn't running. I stopped it straight away.

I have connected a 12v battery to the fan connector and the fan runs fine. I have checked the temp sensor/tstat with a meter and it is open circuit when the bike is cold and is closed circuit when the bike gets hot. have cleaned up the spade connectors and checked where possible and the wires seem to bell out ok.

The item i cannot test is the small square electrical unit screwed to the rad, the cables are encapsulaed as they go into it. What is the function of this part? Could it be stopping the fan from getting 12v?

Am i right in thinking if the bike can run it must be generating 12v o.k. otherwise there would be no spark?

Any help would be greatly appreciated

Roger

[JSE]

TheDodge, on Sep 24 2010, 01:55 PM, said:

Hi,

I have a Gas Gas TXT 02 edition 250 and i could do with some help working out why the fan won't run.

Have not had an issue with it before but today i noticed after 10 mins riding some coolant was coming from the overpressure drain pipe and the fan wasn't running. I stopped it straight away.

I have connected a 12v battery to the fan connector and the fan runs fine. I have checked the temp sensor/tstat with a meter and it is open circuit when the bike is cold and is closed circuit when the bike gets hot. have cleaned up the spade connectors and checked where possible and the wires seem to bell out ok.

The item i cannot test is the small square electrical unit screwed to the rad, the cables are encapsulaed as they go into it. What is the function of this part? Could it be stopping the fan from getting 12v?

Am i right in thinking if the bike can run it must be generating 12v o.k. otherwise there would be no spark?

Any help would be greatly appreciated

Roger

It could be that fan module, but you need to check, with the bike running, for 12V getting to the fan.

The bike can still run with no power put out to the fan/lights as your bike has two distinct generating systems (two sets of coils on the stator), one for fan/lights and another one for the CDI ignition.

Jon

[TLTEL]

Hi
you could try bypassing the theromstat with a piece of wire and starting the bike. Fan should run constant.
you will at least know if the fan is working from the generator out put.
TLTEL

[TheDodge]

Thanks Jon,

Thats great information, will carry out some more testing tomorrow, only had what gear i had in the van at the time.

Are the coils on the stator easily accessable for testing under the engine side cover or does it require removing the stator from the crank?

Does anyone know the resistance i should expect to see through each coil?

Anyway, at least the day wasn't a waste as i got to have a blast on my mates 300 Raga and try out a scorpa

Cheers,
Roger

[TheDodge]

TLTEL, on Sep 24 2010, 09:19 PM, said:

Hi
you could try bypassing the theromstat with a piece of wire and starting the bike. Fan should run constant.
you will at least know if the fan is working from the generator out put.
TLTEL

Will give it a quick check to rule it out completely,

Thanks

[copemech]

Oke, two things to keepin mind on these things is fan/light circuits are both Regulated(to limit voltage) an Rectified( to make fan work, cause it only works with DC voltage).

One can have AC voltage output from the magnetocoils, and a shorted regulator taking it back to earth, or a disfunctional rectifier which does not transform the voltage output(add the prior for a shorted diode) into something the fan needs to run(DC) yet lights work, as they do not care.. A check of the output coils with the motor running and things disconnected should reveal some good AC output normally.

[TheDodge]

Managed to get a bit further on the bike tonight.

Tried the tstat bypass with no joy. Found a wiring diagram online from the ever helpful Jim Snell which gives resistance readings for the wires from the stator. I got 0.7ohms between the yellow and earth which is the wire that links to the tstat from the stator (0.5ohms given on diagram) and 97ohms between the two blue wires from the stator to the CDI (stated 100.5ohms by Jim). no earth leakage was found as stated.

I think this is probably close enough to call good.

Have belled out all the remaining wires on th lights and fan side with no issues so i think i'm down to the regulator or rectifier.

Ran out of light so will check tomorrow to see whether the regulated 12vac is present to the rectifier.

At least i now know i have the japanese electrical system and not ducati sourced electricals which are no doubt made of the finest engineering cheese and disolve instantly in the first puddle. . . (waits to be called wrong)

[TheDodge]

Update:

Fitted a new rectifier today and solved the problem. For U.K. guys it can be sourced from motomerlin for £22.

The only difference between the new part and the 02 part is the new one has a white wire for the ground which has a bullet connector instead of the ground being yellow and on the three pin multi plug. easily sorted with some bullet crimps.

Thanks to those who pointed me in the right direction