choke problems with restrictive pods

[dbeardslee]

Beaver - I still think there's a partial blockage somewhere in your carb vents as that sounds exactly like what mine was doing with that problem - particularly when it was cold. I could take a space heater and set it close to the front of the motor, and after 10-15 minutes I could get it to fire with no choke. As we can't figure out where the 750 carbs are vented, Rasputin's idea might clear it. Increased suction on the vent (where ever it is) with the intake covered could do the trick. Having a fire extinguisher present seems prudent also.

[dbeardslee]

Beaver - Does it act any different with the gas tank filler door open? I know on the 11's there is sometimes a problem with a plugged tank vent not letting the fuel go through. Usually happens at higher rpms, but you never know.

[beaverbeliever]

I haven't tried opening the fuel cap but I can see fuel flowing into the carbs and have fuel in the bowls.

There are 2 vents that I can see for the fuel bowl. There is a vent hole in the choke pick up tube that is right at the gasket surface. There is room around the opening in the gasket surface that draws in air in a grove along the fuel bowl that then is connected to the choke tube opening in the fuel bowl.

There is a second vent that is vented pulls air in from the top of the float area. This is fed from a another hole at the gaset surface of the main carb body. This is a sizeable hole that is clearly open on all 3. I will try placing my hands over the inlets and see what happens but when I have it running albeit a much reduced RPM level under full or half choke and i've tried to block intake openings it revs down and dies quickly.

[TopCatGr58]

A couple more thoughts!

With it running, have you checked for vacuum leaks both at the intake boots, and at the vacuum synch ports, those little rubber caps??? Like DiverRay recently posted, those parts age/harden easily and also are still ON the port metal tube, are loose fitting, and can cause vacuum leaks!

Secondly, are the butterflies set ALL THE WAY closed when you are trying to start on "CHOKE"?? IF the butterflies are set TOO OPEN, then it's not creating enough vacuum to properly suck the fuel thru the choke circuit.

Folks have had problems starting with the choke because they were cranking the throttle plates/butterflies open like on a car trying to pump the carbs, but there is NO pump on these, and opening the throttle REDUCES the vacuum thru the choke circuit!!

Also, folks have had loose intake boots where they bolt to the head, so they couldn't get a good synch because of vacuum leaks, again the rubber boots can harden where they mate against the hot engine head, have had to use gaskets or sealant to get a good seal!
T.C.

[beaverbeliever]

My intake boots are only a couple years old and I've replaced the vacuum hoses from the gas tank petcocks to the engine and also sprayed WD-40 all around the carbs and fittings with the engine running with no signs of a vacuum leak.

I'm really beginning to lean to a partial restriction in the choke fuel pickup circuit. I cranked for a while yesterday with full choke without it starting and then pulled the plugs. They were dry. It's beginning to make sense that at full choke it isn't getting enough fuel to idle up beyond 1500 rpm and moving to half choke where I have cut way back on the air intake it runs better and slowly gains RPM (a leaner choke mixture) and that it needs no choke to start with the throttle cracked and then it will run with full choke and no throttle but at a low RPM.

Now to find a way to clean the choke fuel pickup circuit better.

[Ivan]

Typically you need something more volatile than WD-40 to look for vacuum leaks on a gasoline engine. It doesn't burn nearly as well as gasoline, and usually doesn't give the pickup that carb cleaner does.

On a diesel engine, I use WD-40 for that purpose, as carb cleaner is too spicy, and over used will cause holes in places there shouldn't be holes. DAHIK.

[beaverbeliever]

I've tried wd-40 and carb cleaner with a liberal soaking 4-5 times in all areas that might have air leaks. I did find one in a vacuum hose from the fuel petcocks to the engine but nothing in the carbs or intake boots.