Abraxxas ....

....I saw the same thing a few weeks ago at the field. A guy
and his girlfriend had traveled a long distance to get out
there and fly his new plane. He had another plane that was
OK, but the darned 4-stroker would not run worth a hoot.

Finally out of desperation, he asked me to have a look at it.
I opened the needle way up, and it fired....but the carb barrel
was moving in and out about 1/4", mainly due to vibration.
The "barrel guide/idle stop" screw had backed all most all
the way out, and the darned throttle linkage was the only
thing that was really holding the barrel in....[X(]

We repositioned the barrel and ran the guide screw all the
way in, backed it out a couple turns, and locked it down
with the locknut. After a few adjustments I got the carb
back in the ball park, and it ran fine.

But....good point.....If that barrel is moving in and out....
you can adjust that carb forever........plus, if you lose
that screw....you might be SOL. []

Dave.