At the stock timing spec? That would be very odd unless the float level is very high. My experience is the opposite; very lean.
If you have messed with the IdleTiming, then you probably had to turn the idle speed down. And if you did, then the throttles would be too far down on the transfer slots, and you would need to enrichen the mixture screws.
But if you left the high idle, then it will be getting TOO MUCH fuel from the transfer slots, requiring you to lean out the mixture screws. That's if,
If you messed with the Idle-timing.
But if you left the Factory timing alone, then probably the fuel level in the bowl is just too high.
Here's the test;
With the engine fully warmed up and idling, clamp the fuel supply line off. And wait.
One of three things is gonna happen;
1) the engine will slow down and stall; indicating already too lean
2) the engine speed will stay the same for a long time maybe flare a lil and then make the run to a stall. This is normal.
3) the engine speed will increase steadily, then plateau, then again, make the dash to a stall. This indicates rich.
If yur looking for performance with this carb, extra Idle-Timing is NOT the answer.
As a tuner, without getting into the carb circuits, your first job is to get the transfer slot to mixture screw ratio reasonably-correct at a reasonable idle-speed;
that doesn't hesitate when you tip the throttles in,
doesn't stall going into gear, and
doesn't bang either;
and daymn the IdleTiming. Let it be what it will be. Get that done.
Then you can work on your other timings which are;
PowerTiming
StallTiming, and
CruiseTiming
