We clarify TKM rule C3.4.28 concerning piston rings as follows with new detail highlighted:

  • C3.4.28 Piston rings must at all times remain predominately free (50% or more) to operate in the manner in which they were designed and supplied. It is the responsibility of the driver to ensure that the rings are not ‘coked’ in place with carbon or prevented from their normal ‘spring’ effect by other methods. The rings must be appropriate to the piston size used and have a maximum ring gap of 0.5mm when measured with the ring placed squarely 5-10mm down from the top of the cylinder bore.
  • The top piston ring for both the Junior 100cc and Extreme 115cc TKM BT82 engine must remain in place at all times.
  • The bottom piston ring for the Junior 100cc TKM BT82 engine can be removed if required.

This is effective from 27th January 2015