
Another F2 rider had similiar problems, and this is the mail I sent him,
hope this helps resolve you problem!

AT


Good point, did not catch this in the original post. The only other things 
which come to mind, since this is a gravity feed fuel system, is this.
The fuel petcock valve is vacuum controlled from the #1 carburator. Let
suppose there is a small hole or bad seal either in the hose itself or the
vacuum valve in the fuel petcock. When it is cold, the hole is open enough
to open the valve just enough to allow gas to the carbs with the choke on, 
since the choke creates more low pressure in the carbs when on to draw gas, 
and as the engine and surrounding area warm up, the hole seals up. 

One way to check fuel flow through the valve would be to pull the side 
panels off and remove the fuel hose to the carbs. Connect a tube of the 
correct size, preferably clear tubing to observe fuel flow, on the output
side of the fuel petcock. Remove the control hose from #1 carburator. Make
sure the tank is full. Place the valve in the ON position and apply vacuum 
to the control hose, preferably with a vacuum device with a gauge, to check 
for air leaks. With vacuum applied, fuel should flow freely. To see if there is
a vent problem, do this with the fuel filler cap open and closed, if it 
flows a lot faster with the filler cap open, then there may be something in 
the vent airway which changes position and depending on the position may clog 
or partially clog the vent. I have heard of some F2 fuel tanks being replaced 
to fix this problem. So the things which might be defective are, the control
hose from #1 carb, the petcock valve, and possibly the fuel tank vent.

Now if all of the above shows no problem of fuel flow when cold, then there 
is something in the carbs screwed up, but there are so many things to check, 
I would be typing all day to list them all! 

Here are a few, with everything back together, apply vacuum to the petcock valve
and open the drain holes on the carbs one by one to check fuel flow. Open up the
airbox and check for foreign debris or clogged airways on the carbs, there are
quite a few on each carb.

I hope something is flushed out with all this trouble shooting. If American
Honda does not resolve this, get MAD AS HELL and report them to the BBB and
call the Honda Customer Service HOTLINE. It is a 800 number, but I don't recall
it off the top of my head. I called just about tires for my F2 and a few days
later a customer satisfaction inquiry card arrived at home asking how I liked
the support I received, here would be your chance to tell them what you think!