gsxr 400 gk73a temp gauge

[highway]

im new on here but what a fourum .......
hi all just past my test brought a zzr 400 and a gsxr 400 gk73a
the problem im having is that the gsxr runs mint but after running for about 5 mins the temp gauge goes from 0 to the top off the red but the engine still feels cool is there any think that it could be other than head gasket ...
any ideas would be much appreciated thanks
plus if it is the head would a gk76a engine go straight in as there easyer to pick up

[panda]

Could just be a dodgy temp sender is there signs of oil in water or water in the oil Does it pressurize the water system this would determine head gasket fault

[highway]

i just changed the oil an it smelled an looked ok. i really think its a dodgy sensor as there is no climb in the gauge it goes from the bottom straight to the top even if the head gasket was on the way out surly it would still climb slowly

[Variablevalves suck]

The 76a engine will not fit.
You can test the sensor so long as you have a thermometer and an ohm meter.
From the manual.
156 ohms at 50degC, 53 ohms at 80degC, 28.3 ohms at 100degC and 14.7 ohms at 125degC.

[highway]

cheers for the heads up on the 76a bud was on the cards to get 1 saved me a bit of cash there ...
and ill be geting my self a ohm meter and a thermometer first thing
i dont suposse you no were i could get a manual from bud
and thanks again

[Variablevalves suck]

There is Jap one in the downloads section but its massive so takes ages to download.

[highway]

fixed it ... fan was bent plus the wires had been choped ive wired it to the battery an put it on a switch i no its not the best idea but it will do