Easy balance the crankshaft
Get the bike properly jetted
Make sure the chain and sprockets are not worn or caked up with old chain lube/wax.
A well done tune does wonders to include carb sync,valves set properly, belts set properly, fresh resistor plugs, good gas (87 unless it is a built motor (high comps).
A clutch that is not full of high spots (leading to the dreaded clutch groan), better still a wet clutch. Well better if you prefer smooth over cool