I have an 1986 k100rs and when I bought the bike it never had a fuel gauge. Not even sure if it came with one or just the fuel lights on the dash. I would love to use one and I bought one of AliExpress, I’ve got it to read but it’s showing empty is 3/4 full and full is , well, full. If I was to buy an oem one from eBay for stupid money would it be a simple plug and play? Just want to make sure it’s not the float mechanism that isn’t reading correctly.

'I have an 1986 k100rs'

Changeover year, so it could be either setup; plug on the front-left side of the tank or tail out of the rear. As I can interpret your original post both ways, can you confirm which tank you have?

Clintinz wrote:. . . it’s showing empty is 3/4 full and full is , well, full.

This informative post by Robmack indicates that most aftermarket gauges are incompatible with a Brick's fuel level sender and react like yours but modifications to the sender might be possible if your Brick's tank has the float-type sender. Dai is indicating you need to establish what you have to determine the possibilities.

No longer available from VDO but show up new on Ebay frequently:

VDO 301107

Plug-n-play. The resistance on the fuel gauge is "backwards" like the OEM gauge.  I've replaced the gauges on all of my Ks with these VDO gauges. (Their lenses don't get old and delaminate like the factory gauges.)

Details:
http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/vdogauges/vdogauges.htm

Will an OEM or VDO fuel gauge only work with fuel tanks that have the float-type sender? I ask because when I added an OEM temp gauge to my 1985 K100RS I purchased the harnesses extension for the temp/fuel gauge (61121459488), so I actually have the plug for a fuel gauge.

Thanks.

Thanks guys. I have the float with the wires out the back. The gauge I have does show fuel levels in the right direction just not using the full range so it’s a bit hard to gauge the difference. But by your response Duck and Laitch it looks like it is possible in the OEM and this VOD gauge if I can find one. Great news. Thankyou.

RS Rider wrote:Will an OEM or VDO fuel gauge only work with fuel tanks that have the float-type sender? I ask because when I added an OEM temp gauge to my 1985 K100RS I purchased the harnesses extension for the temp/fuel gauge (61121459488), so I actually have the plug for a fuel gauge.

Thanks.

Yes, you need the float type sender to have a needled fuel gauge. The pre-86 fuel level sender (under the front left corner of the tank) only has two binary sensors for the 4 liter and 7 liter cluster warning lamps.

there is one on ebay now in the UK

Careful. A lot of those 'new' ones are not only not new (NOS maybe - I've seen year 08 dates on a few of them), the internal resistance is 180ohms, not the 130ohms required by the K. Additionally, look at the rear view; many of them require six-pin plugs. Stick to the VDO part number that Duck quotes, unless the internal resistance is clearly stated in the description and it's a three pin input (negative, positive and sensor).

and not cheap looking at the condition bmw motorcycle project fuel and temp gauge | eBay

Keep looking. I've bought full sets including wiring and pods in very good condition for less than that.

Dai wrote:Careful. A lot of those 'new' ones are not only not new (NOS maybe - I've seen year 08 dates on a few of them), the internal resistance is 180ohms, not the 130ohms required by the K. Additionally, look at the rear view; many of them require six-pin plugs. Stick to the VDO part number that Duck quotes, unless the internal resistance is clearly stated in the description and it's a three pin input (negative, positive and sensor).

Very helpful thanks Dai. I’ve had a look on line and there a heaps available brand new but they all seem to be saying 90-0 ohm. Even when they have that model number. Would these work ?

https://vehiclecontrols.com/shopping/shop700/products1/948-301-107-vdo-vision-black-fuel-gauge-for-tube-type-sender-90-0-ohm/#.Y7RkHffTUlQ

https://www.summitracing.com/parts/vdo-301107

Clintinz wrote:

Dai wrote:Careful. A lot of those 'new' ones are not only not new (NOS maybe - I've seen year 08 dates on a few of them), the internal resistance is 180ohms, not the 130ohms required by the K. Additionally, look at the rear view; many of them require six-pin plugs. Stick to the VDO part number that Duck quotes, unless the internal resistance is clearly stated in the description and it's a three pin input (negative, positive and sensor).

Very helpful thanks Dai. I’ve had a look on line and there a heaps available brand new but they all seem to be saying 90-0 ohm. Even when they have that model number. Would these work ?

https://vehiclecontrols.com/shopping/shop700/products1/948-301-107-vdo-vision-black-fuel-gauge-for-tube-type-sender-90-0-ohm/#.Y7RkHffTUlQ

https://www.summitracing.com/parts/vdo-301107

Yes, the VDO 301107 works. It's the one that I use on all of my Ks and recommended in my post above.

Thanks Duck, yes I’ve searched extensively for them I can only find a 90ohm gauge. Would that work? Would it just hold full a little longer?
( I am guessing 0 ohms means empty?) cheers

I sit corrected. I took the 130ohms from Robmack's description of fixing the sender unit. Both of those links are VDO 301107 units as quoted by Duck.

No, 90ohms means empty and zero ohms means full. Opposite way round to logic  

Oh great so those will work then?
I might even have found a link to one way down here in NZ. Thanks for your help guys

One last comment: be sure you buy the electrical version and not the 'tube type' sender version.

Dai wrote:One last comment: be sure you buy the electrical version and not the 'tube type' sender version.

Thanks for that last bit of info as one of those links I found has “tube type”. How can you tell? I’ve found this one on Amazon but there is no helpful description

VDO 301 107 Fuel Gauge https://a.co/d/bZeKM06

And then this one that says tube type. They look identical on the back. 

https://www.partdeal.com/vdo-2-1-16-in-vision-black-electric-fuel-gauge-12v-use-with-vdo-tube-type-sender-301-107.html

Cheers

VDO 301 107 Fuel Gauge https://a.co/d/bZeKM06

Wiring:

Thanks Duck, and sorry for the ignorance, but I’ve been studying that diagram and that is why asked. The back looks identical the to link on partdeal.com but it says it’s a tube type. (Not actually sure what that means) and with @dai saying stay away from those Im not sure which what to buy And with and 8 week wait I’m not wanting to make mistakes.
Can anyone please help direct me to an appropriate gauge?

Clintinz wrote:Thanks Duck, and sorry for the ignorance, but I’ve been studying that diagram and that is why asked. The back looks identical the to link on partdeal.com but it says it’s a tube type. (Not actually sure what that means) and with @dai saying stay away from those Im not sure which what to buy   And with and 8 week wait I’m not wanting to make mistakes.  
Can anyone please help direct me to an appropriate gauge?

As I've stated in several earlier posts I've installed the 301107 in several of my K bikes and IT WILL WORK with the 86+ factory sender.

I prefer them to the factory fuel gauge and use them to replace the OEM ones.

If you choose not to believe me then that's fine with me.

Why would I lie about this?

Disclaimer: I do not own any shares of VDO stock.

The other gauge that will work is the VDO 301 197. It's the same gauge but with chrome trim instead of black.

My K1100LT:

duck wrote:

Clintinz wrote:Thanks Duck, and sorry for the ignorance, but I’ve been studying that diagram and that is why asked. The back looks identical the to link on partdeal.com but it says it’s a tube type. (Not actually sure what that means) and with @dai saying stay away from those Im not sure which what to buy   And with and 8 week wait I’m not wanting to make mistakes.  
Can anyone please help direct me to an appropriate gauge?

As I've stated in several earlier posts I've installed the 301107 in several of my K bikes and IT WILL WORK with the 86+ factory sender.

I prefer them to the factory fuel gauge and use them to replace the OEM ones.

If you choose not to believe me then that's fine with me.

Why would I lie about this?

Disclaimer: I do not own any shares of VDO stock.

Hey Duck it’s not that I don’t believe you I’m just trying to figure out the the nuisances and all information, like the tube type, and ohm ratings. Messages like this can loose context sometimes. And I’m over cautious. If “tube type” isn’t an issue then I’ll get that type and hope they ship within the next 2 months! Thanks again for your time.