Fuel level sensor on petcock

Lots of bikes have or had fuel level sensors, including newer BMW's, sometimes they even work half decent. Most are integrated with a computer module that is typical on later models and that's where they get the power and control for the display electronics. So simple answer is, if your tank was never so equipped, it gets expensive real quick.

Nothing beats a sight level for accuracy and simplicity, but motorcycle manufactures never seem to bother fitting them.

Sb_5.0 said:

Hello I have a 1977 bmw r75 and I am building a cafe racer I had the idea to make a fuel level sensor to it. I see that some of the older moto guzzi bike had them. The r 75 has 2 holes for 2 pet cocks would it be possible to use one of the holes for a fule sensor. And do those sensors power a on/off light or a gauge. I have not seen any one do this. I thought that it would be a unique part of the bike. Thanks

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Sb, As TR said as you are working with the early BMW's you are basicly starting from scratch. You'll need to create a electrical circuit whether you are going to install a "Low fuel" light or a gauge. I would weigh the cost benefit ratio with care. You will need to make a way of installing the send device and if that requires welding (there's nothing we like to weld on more than used fuel tanks; serious fun) and most often it'll include repainting the tank. This is unless you are lucky and everything you are installing mates up with everywhere you are installing it into.

Making a sight glass style gauge as TR has said would be kinda cool and not often done but totally old school and at least the bits wont be expensive.

Cheers

Pretty sure his tank vents through the fuel filler cap which complicates installing a sight glass, if a fuel tank has a vent tube high in the tank and uses gravity feed on the fuel tap, you can install a plastic tube between those two points and have a super cheap and easy sight gauge. Also his bike is pre fuel injection so the fuel tank lacks large access ports for fuel pumps and filters.

I have that exact same gauge on the snowmobile I bought this year, 2 problems, one it's not designed to work on a saddle tank and 2 the pos that came on the machine doesn't work.

... it threads onto a plastic tank

TrialsRider said:

I have that exact same gauge on the snowmobile I bought this year, 2 problems, one it's not designed to work on a saddle tank and 2 the pos that came on the machine doesn't work.

... it threads onto a plastic tank

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Yep does look like a snowmobile gauge. The sight glass I last saw on a classic BSA cafe bike ( this was 30 years ago) was nothing more than two tubes welded to the lower edge of the tank about 5" apart at about the 1 gallon level with a clear tube. I suspect that when the fuel got under that 1 ga level the tube had no gas in it so you knew you needed to find some nice 49.9 cent a gallon gas.

Now it's been a long time since I had a non-EFI BMW so I can't recall the fuel exit to from the tank but if it would work I'd just go with a Pingel valve and when I had to switch the lever I'd start looking for fuel. Problem I think is that none of what we are saying gives the look that Sb is trying for. I think it could be a problem to get something going but like most things I'm sure it's doable but looks to be a lot of work. Most of us back in the day just used valves with reserves. Simple, easy and more time to ride.
Cheers

BigAl8295 said:

That looks like to need it's own hole to mount it.

How about something like this?

Universal Float Free Motorcycle Fuel Gauge FuelGaugePro - Bar Graph Display

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The bmw has 2 pet cock holes so I can use one for the sensor and the other for the fule. Would that work?

Sb_5.0 said:

This is what I saw and what gave me the idea If I fit this on the tank and supply a voltage and ground to a light would this work? Thanks

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That's a low fuel sensor only, it can switch a light on your dash if you have one. Doesn't support a gauge and yes it bolts into a fitting that is welded into the bottom of the Guzzi tank.

TrialsRider said:

That's a low fuel sensor only, it can switch a light on your dash if you have one. Doesn't support a gauge and yes it bolts into a fitting that is welded into the bottom of the Guzzi tank.

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That is exactly what I am looking for so if i put that in the tank and run the wires to the light on my gauge it would work right. Thanks

According to the MotoGuzzi wiring diagram yes, it's just a light switch.