In reply to eman1948 I feel that it may be he who is opinionated, not the scrutineers. Nor are they by and large officious. You can of course get the odd one who is, but you get that in all walks of life. In this case they were simply doing their job, and would have been instructed so to do by the Clerk of the Course (Race director if you prefer). As one who has raced in the Island and sponsored others for over 40 years, I recognise the important part the scrutineers play, and have been grateful for the odd occasion on which they have picked me up on something which I or other team members may have overlooked. They are all the final safety check before the bike goes onto the circuit.
The situation which has happened this year has in my opinion occurred because the promoters of the Classic TT decided not to do any post race checks as happen at the TT and the Manx Grand Prix and this has been the situation until this year. Since last years races I am informed that a number of "sponsors" have questioned the different policy between the 3 events and that presumably has lead to the re-instatement of those checks. Given those circumstances it can easily be seen why some entrants may have believed that they were safe in running oversize engines, only to be caught out by the policy change.
As for the riders, they may provided with a motorcycle by an entrant described lets say as a Yamasuki 750 with only the assurance from the entrant that that's what it is. From my own experience it is very unlikely that they would have any direct knowledge of what is in the motor, let alone what the actual capacity is.
In summary please give the scrutineers a break, and recognise their important role, together with the marshals, and without either of whom there would be no racing.