Topic: Honda CB750A Fuel Guage Doesn't work

[dubepj]

1977 CB750A.  Gas gauge shows full when full, but doesn't show less than 3/4 even when down to reserve.  took it apart and cleaned the rheostat (small wires that metal strip runs over) and all looks good to me.  used multi-meter and shows continuity across the terminals. 
What am I not doing right??  Thanks

[dubepj]

Could maybe be the 7 volt regulator?  Where is it located??

[CycleRanger]

You can get the 750A shop manual and wiring diagrams from here. 
http://manuals.sohc4.net/cb750a/

[dubepj]

I have it but I don't see any reference to test the 7 volt reg.

[RAFster122s]

7V regulator can be replaced with a 5V regulator that is fabricated so the output is 7v instead of 5v... The way you do this is to put a green led diode in the ground lead and don't let the ground pin ground other than through the green led.  The gallium led for the green conventional led, will
Bias the circuit to provide you a regulated 7v instead of 5v.


 The 7507 regulators are no longer made and if you find them they are a fortune. I think Murray of Murray's carbs had a 7v regulator for sale at one point. I think they were around 20.
The 7v regulators were typically used on fuel gauges and temperature gauges of water cooled bikes...
So Goldwing and other Honda bikes often sported a 7v regulator sometimes co-located in gauge cluster or adjacent t to that area.


Fry's Electronics is no more, as is Radio Shack, so, unless you are in a large city or wanna order through eBay or other online shops to build your own regulator, something like one from Murray's carbs or Randakk's Cycle Shack are a good option

[newday777]

Goldwingdocs.com usually has replacement 7v regulators that Scott has found and offers them jumper leads.
I looked but didn't find the link.....

[CycleRanger]

Goldwingdocs.com usually has replacement 7v regulators that Scott has found and offers them jumper leads.
I looked but didn't find the link.....

Here ya' go.
https://goldwingdocs.com/Store/Goldwing-7-Volt-Regulator.asp

They don't mention the 750A specifically but the part may be the same.

[newday777]

Goldwingdocs.com usually has replacement 7v regulators that Scott has found and offers them jumper leads.
I looked but didn't find the link.....

Here ya' go.
https://goldwingdocs.com/Store/Goldwing-7-Volt-Regulator.asp

They don't mention the 750A specifically but the part may be the same.

Ah, they were under site sponsors. I was thinking they were under the for sale section.  I haven't been spending as much time on wing forums the past 5 years.

In the past year someone else asked for one for the 750A and I looked up the part numbers, yes the A uses the same as the GL.