pegscraper
Well-Known Member
Is there really any advantage to running a carburetor with a larger throttle bore area than the cross section area of the intake port? I hear of people using 39mm flat slides and such, or even larger. The stock intake port is a 30mm x 40mm oval, and at the intake surface it has a cross section of 1007 square mm. That area translates to a circle of 35.8mm dia. Stock 35mm VMX carbs have an area of 962 sq. mm. And a 36mm carb would have an area of 1018 sq. mm., which is already larger than the intake area. So assuming a stock intake port - no porting it out larger - is there really advantage to using a carb bigger than about 36mm? Get larger than that and the air velocity through the carb will be less than that in the intake port. Wouldn't bigger carbs just be underutilized and unable to be taken full advantage of?