GK71B Thermoswitch

[terencedactyl]

Does anyone know much about these?
My bike runs very hot - fan not switching on
Did some diagnostics and found fan OK and relay OK if thermoswitch bypassed so think switch is at fault.
I Have a spare from an old engine so tested that in cooking oil - according to manual should short out at 110C and open again at 103C, but no joy. This switch was definitely OK 10 years ago - can they just fail over time? My parts book has a part number of 17680-33400 but a google search finds nothing
Any ideas greatly appreciated.

Regards
TerryD

[Variablevalves suck]

If you can get some measurements and the thread size ive spare bandit4 ones that may work.

[terencedactyl]

If you can get some measurements and the thread size ive spare bandit4 ones that may work.

What do you need - length inside head?

You need a 17mm spanner to remove it. On the outside it has 7D 16 110 stamped, 110 is activation temp.

Thinking about a manual switch in the short term, just hope it doesn't run too cool.

At least it should let me work out if this is what caused my carb problems :-)

TerryD

[GeeKay]

I run a manual switch for the fan on my GK71B - rarely need to use it though.

[terencedactyl]

I run a manual switch for the fan on my GK71B - rarely need to use it though.

I have rigged a manual switch but my bike seems to run very hot and the fan is needed from about 10 minutes use - and riding doesn't seem to help - maybe I need to look at the radiator. So far I have just given it a rudimentary glance - it gets hot :-D

[Variablevalves suck]

There is a 10mm nut on the water pump, losen it and see if any air comes out, if you get air in this part of the system it will air lock and get hot.

[terencedactyl]

Thanks for that, i'll try it on Thursday and see what happens.

[GeeKay]

does look like the coolant system is air-locked.
my bike did 8 full sessions in an afternoon at a track day at Cadwell t'other week (2 riders sharing after his 2-stroke blew in the morning) and it never needed the fan on.