1. Broaden the forecarriage. For the frame of 100cc karts, bear in mind that the basic starting value is 2.5 cm from the end of the shank of the spindle. The broader spacers assembled measure 1 cm, while the thinner ones measure 0.5 cm. Therefore, to make 2.5 cm, 2 broad spacers and 1 narrow spacer are required inside the hub of the front wheel (photo of 100 cc spindle). For the 125cc, the reference starting position is the fourth line starting from the inside of the forecarriage. Bear in mind that a broader forecarriage gives good performance on a mixed, narrow track and on hairpin bends but slows the vehicle down on faster and broader bends.

4. Attach the front bar. This operation generally makes the forecarriage more rigid.5. Increase the caster angle gradually using the 0.5° and 1.5° eccentric cams.

A few observations should be made about steering angles: Convergence must always be performed to zero or slightly open: 1 or 2 mm at the most. In fact, due to the shape of the kart, when it is placed on the ground, convergence tends to close slightly. It must never be positive otherwise, with the forecarriage closed, the kart becomes unstable and seems to float at the front. When you measure the convergence on the stands and it is 1 mm open, consider that, with the weight of the driver and the kart resting on the track, the final value will be zero.


On the contrary, the camber depends on the type of rubber used and the resulting grip. The default setting is zero. The higher the performance of the tyres, the more the camber value can be increased, up to a maximum of 5 mm open below.

8. Move the seat forwards, bearing in mind that a basic measurement is:
for 100 cc: distance between end of seat and start of front crossbar: 58.5 cm on right – 59.5 cm on left – height from axle: 22.5 cm (with frame high). For 125 cc
distance between end of seat and start of front crossbar: 59.5 cm on right – 60.5 cm on left - height from axle: 22 cm (with frame high).

If understeering persists, there may be two different problems and solutions. The frame may have structural problems caused by a collision and is therefore distorted, or the understeering felt by the driver takes place because, as mentioned previously, the kart turns excessively at the front and therefore “sits” back as it moves out of the bend, applying an excessive driving force on the vehicle.

In this second, less serious case, simply undo the changes made and take action that will increase the stability of the rear axle.