I was riding a trial at the weekend and the bike started over heating,

I've since checked the fan, thermostat and all wiring and all seems ok, the water pump to is ok. Can't seem to see any thing obvious possibly n intermittent fault on the thermostat(temperature switch) any one had any similar problems or any ideas what could have caused it?

I've seen there's a different water pump you can get off another web site, any body put one in and think there worth it or any difference?

Cheers Steve

Has your oil gone creamy in the clutch cover window?

No it's new oil in and it's all nice and clear.

First check is to make sure fan is coming on, start it up and check the fan is working.

Now disconnect the fan from its plug and wire it up to a battery to see if it comes on every time you connect a circuit. Try it several times, if the motor doesnt spin once or twice the motor is faulty. My fan motor packed up and it ran occassionally when it wanted to, and it was over heating for no apparent reason. The fan motor was actually knackered and I only realised this when I rigged it up to a battery and checked it. if your motor is knackered get a graupner speed 500 e motor from cornwall models fir about a tenner and replace it (cheaper then buying from gas gas).

If the fan is good and you are sure the wiring is good you can check the thermostat by removing it from the rad and dropping it into a kettle of hot water, probe it with a meter to see if the contacts close.

How do you know its overheating?

I had a customer's 2011 GG that appeared to be overheating due to the coolant coming out the overflow hose - turned out to be a faulty Radiator Cap that could not hold back the pressure as the bike warmed up.