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I apologize for thinking you're a bonehead, and I give you points for having the balls to respond. That's a great accomplishment in this emasculated PC society that values wussification.
I'm going to start at the beginning so that this will make sense.
Triumph specificaly built these bikes for the European market and to comply with German laws that basically limited the horsepower in one class of motorcycles to 70 PS (PferdStarke = HorsePower).
Meeting that requirement resulted in the highly restricted airbox, crappy exhaust and wimpy cams in a carefully balanced configuration that produced a pretty good running bike. Not a road-burner, but a bike that does everything well without real excellence in any area.
Opening the intake system (pod filters, airbox mods) produces about 70-75 RWHP. It doesn't seem to matter what intake mod is done because the system of intake, cams and exhaust are optomized to produce 60 RWHP by limiting airflow. The application of airflow limitation was so effective that changing both the intake and cams still produces the same 70-75 RWHP with the stock exhaust! Likewise, a high-effeciency exhaust system with the stock intake only produces a small change in output.
FCR's on the other hand are designed for high airflow efficiency with no compromises for what the simpering EU bureaucrats think. Moving from the CV 36mm to the FCR 39mm is about a 17% increase in throat area with a *much* higher potential for airflow than the area increase suggests since airflow is an exponential function of area.
That increased airflow is important for performance, but not quite in the way most folks think. If you've still got the stock cams and exhaust system you're never going to realize the increase in potential that the FCR's present.
The way a carb works is to develop a high velocity airflow through the venturi of the carb. Because it's high velocity, there's low air pressure that sucks fuel out of the float bowl, through the jets and into the airstream. (Look up Venturi Effect and Bernoulli's Principle if that doesn't make sense.) If the airflow velocity too low from opening the carbs too far, fuel flow into the airstream is severely reduced and the engine bogs down.
The cool thing about the CV carbs (either the Mikunis or Keihins) is that they have a variable venturi that's air velocity actuated and not under the direct control of the operator. They're adaptive in that regardless of the throttle input by the operator, the actual throat opening is controlled by the functioning of the slide assembly.
Think of that automatic control function as the 'babysitter valve' that prevents tyros from whacking the carb open and lowering the throat velocity to the point that the carburetor doesn't carburate any more.
Without the 'babysitter valve' your FCRs make it possible to open the throttle too far and lower the velocity to the point where there's insufficient pressure differential in the ventury to draw fuel into the airstream. That will allow you bog down the engine at almost any rpm range if you've got the stock cams and exhaust system.
SO... Full throtle with the FCRs is a bad thing for most bikes. The FCRs require that the operator respond to the engine demand and adjust the throttle accordingly. The priority of the CV carbs is to respond to the engine demand with only a limited response to input from the operator.
Make sense now?
Jim
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