The nuts and bolts of rejetting a carburetor depend on the carburetor you have. The generic answer is that you get larger main metering jets for your carburetor, then disassemble the carburetor, remove the old jets and install the new ones. Depending on the carburetor, you can often do this by only removing the top (bowl cover), without removing the carburetor from the engine. You should have more than one jet size, so you can try different sizes until you get the performance you want. No matter what you do, check the spark plug color after driving a short distance (25-50 miles or so) after each jet change. A good color for spark plugs is off-white or light tan. Bright white porcelain may indicate that the fuel mixture is too lean- larger jet is required. Dark tan/brown/black spark plug color indicates the fuel mixture is too rich- smaller jet required. If your carburetor has metering rods, they also (sometimes)come in different sizes, to permit changing the power mixture. Metering rods slide into the main jet and restrict its opening for light-load operation. Main jet size is identified by a number stamped on the jet- larger number means larger jet. In the past, it was common practice to drill the jets to a larger size, but that is not a good idea.
Also, when you are driving the vehicle after the jet change, listen for detonation (spark knock/pinging) both at light throttle, and at heavy acceleration. Detonation also may indicate that the lean fuel mixture is too lean. Before you make any changes, listen for detonation and check the spark plugs, so you know if your jet change caused something that didn't exist before the change.
I'm assuming you don't have access to a chassis dynamometer and an exhaust analyzer. If you do, life will be much simpler.
Keep in touch.
Harvester
