Go kart chains eventually stretch and release themselves from the sprocket, making the drive chain inoperable. You can choose from four different chain sizes: No. 35, No. 41, No. 420 and No. 40. You'll need to take four measurements to determine the chain size you need.
Place the tip of a measuring tape on one side of a roller in the chain. Read the measurement on the other side of the roller. The roller is the round barrel in the centre of the chain. Standard roller diameter measurements for go karts are either 3/16-inch or 5/16-inch. Write this measurement and all others down on paper.
Turn the measuring tape 90 degrees and measure the length of a roller between the two flat sides of the chain.
Lay the chain on a flat surface with the outside pins facing up. Measure the chain pitch by placing the tip of a measuring tape on the centre of an outside chain pin and measuring to the centre of the next chain pin. Go kart chain pitches are either 3/8-inch or 1/2-inch.
Hold the chain in your hand with the rollers facing up. Turn the chain to find the master link pins. The master link pins are smaller around than the rollers and there are two side by side in the chain. Measure the diameter from left to right of a master link pin. The pin diameter will be either 1/8-inch or 5/32-inch.
Mark one link on the chain on a roller with a marker. Count this link as number one and continue counting all of the links on the chain, omitting the two master link pins. Multiply the number of links by the pitch size to determine the chain length you need.
Order or purchase a new go kart chain with the roller diameter, roller length, pitch, master link pin diameter and the length.
Order a longer length of chain than you need and remove extra links by pushing the chain pins out with a punch. Many go kart chains have the size printed on the side of the chain for easy reference in purchasing a replacement. Regular chain lubrication provides a longer life for go kart chains and prevents stretching.