I fitted the bwm temp sender from motorworks, but bought a temp gauge from hong kong via ebay.
Could i be getting false readings? Im asking because the temperature gauge soon goes to 120 but the bike seems to run ok.

should the sender and temp gauges be matched? or should i try a better make of gauge and see if its different.

Badger
I reckon you'd be best off with a bmw gauge even a second hand one
as its calibrated to deflect in a way that corresponds with the falling resistance of the
sender as it gets hotter.
matching up an odd pair could be tricky as you'd need to know the electrical characteristics of
the gauge and how to compensate for that.
I doubt its even a linear one which might be easier to patch in

If its not matched with the sender, I'd ignore what the gauge says and assume its reading high
that 120 is just a number on an unmatched system not a temperature.
thats assuming the bikes actually working at the correct temp and thats another assumption
and we have to be careful about making assumptions

What you could do in the short term is find out the resistance of the sender at
normal running temp
Lets say its 50 Ohms which what my CX runs at, I havent mapped out the BMW one

You stick a 50 ohm resistor between the detached sender wire and ground then watch the gauge
Whatever it deflects to is close to your normal running temp despite what it says on the face
At least you'll have some idea if the motor is running hot or not

Thanks for that, i have looked at the bmw one but boy are they expensive. Will look for one coming up on ebay and hopefully will get a bargain.

the BMW sender gives about 90 C/50 Ohm. Most gauges will be OK as long as 40-120. 50-150 are not right.
Look in the info for the gauge, it should give you some indication. I'm using a VDO which indicates perfect.

Thanks, teach me for buying a cheap one from ebay, just bought a proper bmw one from the US, £60 posted so not too bad a price compared to prices here.

I knew i should have got a smiths or vdo in the first place