Fuel starvation problem resolved
Fuel starvation issue
Several weeks ago I changed the needle
& seat in the carburator. The issue, then, was fuel
overflow/spillage after starting the motor. I would never notice
fuel overflow after a flight - only at initial startup. I am
unsure if it was overflowing during flight. A needle & seat
set was pulled from the old carburator that was on the motor when I
purchased it. At that time I also lowered the fuel level that is
maintained in the fuel bowl - changing two items at one time.
After the change, upon full throttle settings (take off), I would gain
about 30 to 100 feet of altitude and the motor would stumble just for a
moment. It would not loose more than a few hundred RPM but it was
certainly noticeable. At about 80% throttle it would run
fine. There was no overflow/spillage problem at startup.
A subsequent change was to increase the fuel level in the fuel
bowl. No spillage was noticed but the starvation issue
Today I pulled the carb off of the motor and was going to put the
original needle / seat back into the carb. It was then that I
compared the original needle & seat to the old needle &
seat. The "good" needle & seat set on the left, marked as a
3.3 if I recall, has a much larger hole for fuel to flow through
it. The "bad" needle & seat set on the right was marked with
a 7.5 (I think). With the larger diameter hole more fuel is
capable of flowing through the assembly when it is open thus keeping
the carb bowl filled with fuel for the motor's needs.
The next step is to adjust the float level a bit lower to see if the
overflow/spillage problem it eliminated.
So with that taken care of - time for a test flight...
Wind, calm, was from the East-NorthEast so into the wind I go.
Bare track from the GPS
(click for a larger image
With the track data placed onto a street map and annotated
Temps are right in line - the right amount of fuel is being processed
by the carburator
Click for a larger size
Some nice patterns in the harvested soy bean fields
A soy bean (or maybe corn) field that has yet to be harvested
Looking east towards Rockford and Belvidere
(click for a larger image with markings for the
Only against the dark green grass are the guy wires visible.