Chainsaw Repair

The saw I was referring to  is a race saw that's had the port time area opened up and velocity through the intake in particular was too slow with the particular .945 venturi carb that was on it.  The fuel signal on the main jet was poor and it didn't vaporizer is the venturi as you would normally see.  Added a screen to the main jet which helped but in the end the carb was too big.  Smaller .750 venturi was a huge improvement.   Seems to me that the stock ports have been optimized for tight crankcase pressure , hence the tiny transfers with relatively long blowdown to minimize loss through the exhaust.   

A .945 venturi is too larger for the 20 hp honda GX200 motors I build.  I stick with the 334WXA which is .75" I think.