45mm throttle bore with 42mm venturi designed for large CC alcohol engines.  Works great on many different UAS engines.  Many have been built for 250CC and 500CC 2-strokes and 450 4-strokes.  Currently many 450s running this carburetor have eliminiated the need for a radiator. 
 
*Usually the billet silver is the color in stock, but this can be limited at times.  Color shipped will be based upon what is in stock.  Contact us with questions on color options.