Overhauled the Bings and now it won't start. Good, strong spark so I must have screwed up something in the carbs. Just replaced the O-rings and bellows and cleaned everything up. All jets and needles are the same. There is fuel in the float bowl. Air mixture screw out 1.25 turns. Any suggestions?
Did you disassemble the chokes (enrichment valves)? They are not interchangeable right and left. Must go on the correct carb. Also the shaft must be oriented in the correct position. See picture with dot on end of shaft.
Did you disassemble the chokes (enrichment valves)? They are not interchangeable right and left. Must go on the correct carb.
That's my question too. Did you disassemble both carbs at once ? There are several parts that look very similar, but are "mirrored" and only fit one side. The enrichening valve plates are the most well known, but there are several others.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Thanks, guys! Specifically did only one carb at a time. Dots aligned properly.
Did you put the fuel in the bowl in attempt to prime, or it was delivered there from the tank? What I am getting at is, did you check the petcock is on, are you sure the needle valves are stuck or having stiction? Try wrapping the fuel bowls with a screwdriver handle.
If the fuel is delivered as intended then you got a pick up issue. How did you clean these during the rebuild? Carb cleaner? Compressed air? Ultrasonic? Dip? Did you check all passages for clearance?
How are your elbow to card and carb to head 'manifolds'? Any chance of an upstream obstruction (airbox)?
Sorry for some basic questions but we ALL have been kicked in the butt by missing a simple thing.
@18533 After reassembly, had to readjust floats because both were filling to overflow, meaning that flow from petcocks is good . Cleaning by spraying with carb cleaner and blowing out with compressed air--checked all passages for obstruction. Will check upstream and carb to engine head "manifolds" next. Thanks!
Have you found the problem? Going back a bit - when you say it won’t start - does it just spin without firing, or does it fire and try to start? If the enrichment circuit is ON, and working (drawing fuel) it should fire and kick.
if it is not firing and trying to start, then the enrichment circuits are not drawing fuel and dumping it in the intake. Need to focus there.
@4949 Not firing at all. Engine is spinning, full choke, nothing. Sounds like repeat removal/disassembly is in store, right? What/how to check in enrichment circuit? (Old newbie here)
IMHO, if it just spins (w/spark) on full choke and doesn’t fire, the enrichment circuit is not working. First, are the carb butterflies closing ok? Vacuum behind the butterflies draws fuel thru the enrichment circuit. The circuit starts in the fuel bowls. There is a narrow “well” in the front corner of the bowl that feeds the enrichment circuit. A pickup tube extends into the well when the bowl is mounted. At the bottom of the well is a tiny jet opening that meters fuel into the well. Make sure that jet in the bowl is clear and clean. The bowl gasket includes a ring around that well, which needs to be in good shape and seal to retain vacuum. So, the fuel gets drawn up the tube and into the rotary valve actuated by the choke cable. The valve controls the enrichment flow rate, and of course shuts the circuit off. From the valve, the fuel goes directly into the intake tract just past the butterfly. You will see the large exit port at the 4 or 8 o’clock position. All that said, if the bowl gasket and the little jet in the bowl are ok, and there is fuel in the bowl, of course - then you could check the choke operation with carb cleaner or gentle compressed air. With the bowl off, activate the choke and pressurize the pickup tube sticking down. It should come out the port by the butterfly. Moving to half choke should decrease, and all the way down should shut it off.
Oops - editing here. I forgot that the enrichment circuit also draws air thru a port on the intake end of the carb at the 3 or 9 o’clock position. When you test w/pressure, you could put your finger over the port. That should send it all to the port by the butterfly. And, vice-versa. Just check that all these passageways are clear, and on is on, and off is off.
@4949 Dave, Thanks so much in advance. Will be a couple of days before I can get to it. REALLY appreciate the help. Butterflies work--idle screw was set one turn after seating on fully closed valve.
All, OK, Old Faithful is running again! It was apparently a combination of minor things: float levels set too low and therefore, choke siphon couldn't pick up any fuel. Readjusted the float levels and insured the choke pickup reservoir inlet jet was clear (some kind of green gunk in there that I didn't notice before) and voila! Suspect that the fuel levels in the bowls were too low for the choke siphons to pick up fuel. In any case, I'm on the road again! THANKS FOR ALL THE HELP!!
Would be nice if we had a spec for ideal float bowl fuel height. Or, maybe we do but I just don't know it!All, OK, Old Faithful is running again! It was apparently a combination of minor things: float levels set too low and therefore, choke siphon couldn't pick up any fuel. Readjusted the float levels and insured the choke pickup reservoir inlet jet was clear (some kind of green gunk in there that I didn't notice before) and voila! Suspect that the fuel levels in the bowls were too low for the choke siphons to pick up fuel. In any case, I'm on the road again! THANKS FOR ALL THE HELP!!
Yeah! Victory!
Good news you have it running. I do believe repair manuals or the Bing book do give details on how to adjust the floats properly. I haven't done it in awhile so I will bow out on trying to explain the proper set up. St.
Beware! I do not suffer fools gladly! St.
Advertisement
