If you can not
obtain a consistent mixture or a rich enough high speed mixture
check inside the spray bar. Many times something is plugging
up the metering slot that controls the fuel flow for idle
and midrange. Symptoms are not being able to obtain idle settings,
not getting a rich enough high speed setting, and erratic
If you have trouble
with a rich idle and are unable to adjust it properly and
you have checked all of the above, The inner tube of the mixture
disk (where the slot and hole are in the picture to the left)
may have excessive wear with the mating tube inside the barrel.
This is a very close and precise fit. If it is loose it will
not meter the fuel properly at idle. Kinda like a leaky faucet.
At this point the carb should probably be replaced or at minimum
the mixture disk and barrel replaced.
A good fit must
also be maintained between the barrel and body. If this is
worn, you will have air leakage and not be ably to get consistent
idle or have the ability to shut the engine down when carb