Please note this clarification issued on 28.6.19:
Honda Classes including Honda Cadet:
An updated, more environmentally-compliant Honda T2 engine is now in circulation with engine preparers and will shortly be seen at circuits. The external method of identifying this engine is that the engine number will start with a “4”. The only other obvious identifying factor is that the flywheel magnet might well be mounted in a green coloured holder. Scrutineering in all aspects will remain the same as current practice and it is not anticipated that this updated engine will require any regulation changes.
Please be aware that this engine will not be eligible for the Motorsport UK Honda National Championship during 2019. A notice to that effect will be issued as a bulletin to all competitors in that series.