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What cc will the following be ? Uprated AF Crank- 60 mm Japanese con rod- 3 mm Packer and standard'ish barrell. I am trying to calculate this to get the jetting spot on with a 30mm carb.

St George wrote:What cc will the following be ? Uprated AF Crank- 60 mm Japanese con rod- 3 mm Packer and standard'ish barrell. I am trying to calculate this to get the jetting spot on with a 30mm carb.

The swept cubic capacity of the top end is determined by the bore & stroke, regardless of rod length & any packing.

The cubic capacity (volume) of the bottom end is variable with various factors such as packing, crank webs, rod & whether the magneto bearing is sealed internally or not. You’d need to measure that.

The cubic capacity (volume) of the cylinder head is also variable with various factors such as gaskets (avoid like the Plague..) & squish. You’d also need to measure that.

Many thanks, will go to plan B.

St George wrote:Many thanks, will go to plan B.

Presumably Plan 'B' will be to look @ AF Rayspeed's chart as it is a great starting point, in my experience.

With respect, you may have been barking up the wrong tree to estimate jetting based on cc.

Carburettor type, barrel & exhaust are the significant factors that set the parameters to be used in most jetting guides.