HELLLLLLP!!!!
 

Ok i have just got a new Novarossi engine Yipeeee And it comes with 3 carb inserts it is fitted with the white but has red orange and black checkes instructions amd it does not tell me about them i no it must be somthing to do with air flow this is a onroad engine on 25% nitro which should i use :weird::tire::tire::tire:

They are called restrictors, they limit the air intake. A larger opening means more air and that means more fuel is needed, ofcourse that will give more power.

A smaller one does not give that less power but it can be noticeable and can save you a fuelstop in a 5 minute qualification. In this situation you have to decide whats faster.
Just start with the largest one.

On the edge there is a number, the black is 9mm and the red must be 7 or 8mm