Lets grow the sport
So the stock engine will be set at around 3000 rpm.
We need to be up to 5500 to 7000 rpm. The easy was to gain rpm is to replace the stock governor spring with a heavier one or in some cases two. The problem with this is it puts a lot of strain on the linkages for the governor. Basically the heavy spring is to fight against the weights that make up the mechanism.
A better way to approach it is to remove the governor assemble completely and drill the cast iron weights to lighten them up and then add a heavy spring. I normally drill 4 19/64 holes in each weight being careful to make sure the spacing is the same on both. It should look something like this.
Removing the governor requires you to remove the front cover of the engine as well as a cap below the fuel pump to gain access to a snap ring.
After the drilling is done replace the governor spring. I use a spring from the company Century Spring part number is C-171 and if you find you need more rpm still there is another spring C-135 that fits inside the other one. These are found on Ebay for less than 10 bucks. Just a word of caution when ever you are doing work on pump or governor springs always remove the crossover pipe and have a metal plate handy to block the intake just in case you have a run away.