TOPIC:

I think maybe this is the easiest option, to go for a different tank. However this would be the third tank for my bike and the last one I had shipped from the States as it is cheaper than in the UK.

The annoying part is that I can not even get the light to work.

In the UK is it? Well there are Tanks on FeeBay for sure. Try asking KZ10006 with a PM, I just bought centerstand from him. He is in new York, and has parts from a CSR. He may have a tank, with the sender instead of switch. According to Kawasaki there are 3 tanks for the 82 M2 CSR. Two Ebony and one Blue. While I can't find out which, they show both the switch and a sending unit available for the Bike. Look:

So there is both.
the three tanks are 51001-1081-8G TANK-FUEL,EBONY: 51001-1081-8K TANK-FUEL,S.BLUE: and 51001-5096-8G TANK-FUEL,EBONY
I looked and there are different #'s for the K2 which is the LTD. The seats are the same # but the Frame is a different one. But I think the Tank would fit, the LTD doesn't have the same paint scheme.
Ask KZ10006, Brian, as he may have a good tank with the sending unit instead of switch.
Also posting a Wanted To Buy here on KZR might get you one.

I just read that the switch works with a thermistor. So in the little cylindrical housing at the end o f the switch in the tank is a thermistor, which changes resistance when no longer submerged in fuel. This trigger the fuel warning light to come on. This gave me an idea. If I make a long thin tube which I can bend along the shape of the petrol tank from the bottom all the way up to the top, i could fit thermistors in series and say if the length is about 300mm I could maybe fit 10 to 15 thermistors with the total resistance value of 120 Ohm (manual says when empty the sensor shows 102-118 Ohm) taking the differences in fuel volume per cross section in to account. This way I get a variable resistance reading same as the float sensor in a thin space to get it through the fuel switch hole and not to worry about any moving parts. as long as the thermistors are fuel resistant I think it could work. I might have a trip down the local electrical store tomorrow.

that sounds like an interesting project. Can you post up the info once you obtain it, for the parts required? What does the switch components look like? A thermistor should change resistance when temps change, hence the Therm in its name.

Yes, it sounds interesting, but I need to understand how the current set up works. I thought of some problems with it, i.e. if it works on temperature change how does such system work in summer or winter or when the fuel is cold and gets warmer with the engine radiating heat? But I think I have a go, but as I said I need to wind out a bit more.
I have measured the resistance on a sensor which I have from the old tank. I get 3kOhm when at ambient temperature (about 20degr) and it go down to 2.2kOhm when I hold it against a light bulb which I would guess increases the temperature by maybe 20degr.
This is the sensor or switch:

Well I don't know if that is a Thermistor. Although the system does work on resistance, I don't know how that would function just on temperature. Try checking the resistance, while immersed in fuel at different levels.
I think it will change resistance as it gets covered then uncovered with fuel, maybe other liquids to. But I don't know what type of resistor that is. Just varying the resistance to ground, so limiting the current to the bulb, it would first come on dim then get brighter.
I doubt after years of being in a fuel tank, there are any Identifying marks/ numbers on the resistor element?

I have asked the person who sells the thermistors on ebay how to test it and in his replay was this information:
To test the sensor you have to make sure the gas in the tank is below the sensor tip. The sensor lights the bulb when it has no gas touching it. It is cooled by the gas, so when gas is around it, it will not make contact inside.
So it is just a straight forward on/off or low and high resistance when the fuel is belowor above the thermistor level. This is what I measured and this is what I need to get my gauge showing the right information. C (cold) is empty and H (hot) will be for full.

I know when parking my bike after a run, it sits there and the fuel vaporizes. Coming out the tank vent in the cap with great force. Sitting right above that hot motor, you can feel the heat in the Tank, fuel included. Seems like the fuel its self would go through a wide temp swing. But I guess that the resistor works that way, as they seem to be used in several applications, for the low level switch.
How many are you going to Series together? Will that give you a contact through them, or if one is out of the Fuel, will it be an open circuit? I'm just wondering why the Manufactures don't have something like this set-up, so they would have no moving parts. Cost?

I just did a quick calculation, but I am not sure if I ever get components to fit. I also have not taken any other influencing factors in to account such as temperature changes due to hot and cold weather.





You commented:
I'm just wondering why the Manufactures don't have something like this set-up, so they would have no moving parts. Cost? Maybe it is because it does not work????

I found an interesting fuel sensor from a Harley Davidson, wonder how they work and if it is easier to adapt them for what I want to do?

That Hardley one looks interesting. But also it is quite large on the Length and the Threaded fitting.
I suppose there are many different designs out there.
It will be interesting on what you find out experimenting with this. On my bike the float bounces with the fuel, so it does not have a steady reading, it moves around at least a 1/4 of the scale. Sometimes more. I've soldered the ground connection where it was slip spade terminal, cleaned the contact and wire wrap, checked the resistance. The gauge is mounted well, terminals are tight.It reads fine till the level starts to drop, so I know its sensor related. Maybe your configuration would provide a rock steady reading.

Never thought trying to get some a bit special electronic components is so difficult. If you don't want to buy a container load from China nobody wants to know. I finally found a place which used to be a shop I went to when I was younger, which is now on-line and ships the components. Not cheap, but at least I am able to get something which I can use. So the thermistors are on the way and I hope it will give me at least some results to work from. I found a thermistor which has 3 Ohm @ 25deg with a positive coefficient, i.e. increases in resistance when getting warmer. This is what I need when the fuel does not cover the thermistor cooling it down.

My thermistors came yesterday, but I ordered the wrong ones. So I will need to wait for the replacements.