RE: MOKI RADIAL Care and Maintenence
My 150 does the same thing, and I've heard from others who also experience an RPM drop when the carb is at full throttle.
There could be a couple of explainations:
It could be perfectly normal, or,
The carb may not be able to deliver enough fuel to accomodate the amount of air coming in at full throttle.
If "not enough fuel" is the issue, that would explain why people are experiencing better results with teh external fuel pump. I purchased one of those pumps, but have not installed it yet.