Fuel flow?

[XSLeo]

The 78-79 carbs vent the float bowl from the carb bell. All the earlier carbs vented with tubes as in my pic.
If you look at my pic you see the large curved hole at the top and two holes down on the sides of the carb bell. On the 78-79 carbs there is a second set of holes just above the ones in my pic. This extra set of holes are the vents for the float bowl.
Leo

 

[sipovino]

I'm having the same exact problem! When petcock is initially turned on or reserve, the fuel flows fine and fills up the hose. While riding, eventually it stops flowing. When not connected, the petcock flows freely as it should. The carbs are clean. New petcock and new rebuild kits on carbs. Anyone find a solution to this problem? Oh, when left with the petcock on off position for a few hours or overnight, the fuel line sometimes fills completely up. Makes me think the petcock is malfunctioning even though it's new. My carbs are BS34.

 

[gggGary]

I'm having the same exact problem! When petcock is turned on or reserve, the fuel flows fine and fills up the hose. While riding, eventually it stops flowing. When not connected, the petcock flows freely as it should. The carbs are clean. New petcock and new rebuild kits on carbs. Anyone find a solution to this problem?

Does the engine stop from lack of flow?
When fuel flow stops or slows open the gas cap, see if that "fixes" the issue. Clogged gas cap vents are common, the vent path is convoluted and travels though some gasket material that can swell.

 

[sipovino]

Thanks for the quick reply gggGary! Yes, the engine eventually stops when the flow stops. I did take off the gas cap but didn't make a difference.

 

[gggGary]

Do you have "extra" filters installed? Remove float bowl drains then turn on petcocks. What happens? What year and or carbs do you have?
Have you removed, cleaned petcocks?

 

[sipovino]

Do you have "extra" filters installed? Remove float bowl drains then turn on petcocks. What happens? What year and or carbs do you have?
Have you removed, cleaned petcocks?

Yes, I have an inline fuel filter. I've got 1983 carbs. Right now the fuel is flowing freely when float bowl drains are out. I will test again when fuel is not flowing through. I have to run it a bit for that to happen it seems.

 

[gggGary]

As delivered 80-84 BS34's have a small fine screen above each float valve. Check your petcock vacuum line and fittings. Have valves been set?

 

[sipovino]

Yes, it does have the fine screen above the float valve. My petcock has no vacuum line. I did adjust the valves to spec.