Short answer- - - - -reduce the throttle pressure a little. There's a mechanical linkage from the carburetor to the transmission with a turnbuckle-type adjustment in it. To make the trans shift sooner, adjust the linkage so the small bellcrank on the side of the transmission does not travel as far when the throttle is opened. VERY small adjustments can make a big difference in shift points, so don't overdo it.
Longer answer- - - -Adjusting throttle pressure for a sooner, softer shift sometimes reveals a more serious problem- - - - -worn or maladjusted bands. You'll need a factory service manual to do a proper band adjustment. There aren't any real shortcuts to this procedure, and shade tree methods usually result in worse performance and possible internal damage.
Jerry
