The throttle shaft bore can be blocked opposite the shaft linkage side with a plug to prevent air leakage. A copper plug was pressed in, available at one time from part suppliers.
I would suggest assembling the throttle valve in the throttle shaft each time you want sand or file on it. It holds the valve "square" in the bore, otherwise you run the chance of it being crooked in the bore.
The throttle shaft bore can be blocked opposite the shaft linkage side with a plug to prevent air leakage. A copper plug was pressed in, available at one time from part suppliers.
I would suggest assembling the throttle valve in the throttle shaft each time you want sand or file on it. It holds the valve "square" in the bore, otherwise you run the chance of it being crooked in the bore.
The horn is not as important as the carburetor. Just my opinion.