Fuel guage

[ALB80-850]

I have an 86 GS1150 with a dynojet stage 3 kit, pod filters and aftermarket exhaust. My issue is the fuel guage reads much faster the the fuel being used. I've been monitoring the mileage and am getting around 38mpg. Over the weekend I was at 130 miles on the tank, guage read empty, had to switch to reserve at 135 miles. Stopped at the first gas station to fill up and only took 3.5 gallons. Is this normal for this bike to have a 2.5 gallon reserve? Or could the petcock be off a different bike and the taps are higher in the tank than needed? I haven't pulled the petcok yet as the tank is near full. Any guidenance would be appreciated.

Andy

 

[JTGS850GL]

The fuel gauge is independent of the fuel petcock. It's nothing more than a float tied to a variable resistor. If the gauge is reading incorrectly then it's either the float assembly or the gauge itself.

 

[Steve]

It's possible that the petcock is not the correct one for your bike. 2.5 gallons in reserve is at least twice the normal amount.

There are a couple of ways that I would address the problem.

1. Get the reserve amount back to the expected gallon or so by installing a proper petcock.

2. Recalibrate your fuel gauge so that, with one gallon in the tank, the needle is pointing at the bottom of the white area and the top of the red.
The downside of this approach is that you will have to flip the petcock lever at some arbitrary point in the needle's travel, but it might be hard to judge exactly when.

If it were my bike, I would do both of those, with a slight modification to #2. Instead of measuring out a gallon of gas for reserve, I would just fill the tank above the reserve level, then let it drain down to that level and calibrate the white/red transition area on the gauge to that.

.

 

[JTGS850GL]

It's possible that the petcock is not the correct one for your bike. 2.5 gallons in reserve is at least twice the normal amount.

There are a couple of ways that I would address the problem.

1. Get the reserve amount back to the expected gallon or so by installing a proper petcock.

2. Recalibrate your fuel gauge so that, with one gallon in the tank, the needle is pointing at the bottom of the white area and the top of the red.
The downside of this approach is that you will have to flip the petcock lever at some arbitrary point in the needle's travel, but it might be hard to judge exactly when.

If it were my bike, I would do both of those, with a slight modification to #2. Instead of measuring out a gallon of gas for reserve, I would just fill the tank above the reserve level, then let it drain down to that level and calibrate the white/red transition area on the gauge to that.

.

Even if the petcock wasn't the correct one for the bike, the fuel gauge would read higher then empty when it went onto reserve. If the gauge was in error but the petcock was correct, then the fuel gauge would read empty for a much longer period of time.

With out knowing the actual tank capacity I couldn't say for sure if there's a problem or not. 5.2 gallons is the number I remember but I've also heard that the California model only had 4.8. The numbers he's putting out would indicate he thinks the tank capacity is 6 gallons (3.5+2.5). If it was 3.5 gallons used and the actual capacity was only 4.8 and he used 3.5 then the actual reserve was 1.6 gallons. Not as outrageous as the 2.5 gallons originally posted.